Re: [PATCH 1/1] iommu/vt-d : clear old root entry for dump kernel
On my system, error message: [4.322008] dmar: DRHD: handling fault status reg 2 [4.327484] dmar: DMAR:[DMA Read] Request device [21:00.0] fault addr fff66000 [4.327484] DMAR:[fault reason 01] Present bit in root entry is clear fault happens on device : 21:00.0 To describe this problem clearly, we mark two time points: A: Just before dump kernel init the DMAR/IOMMU structures. B: Just after DMAR/IOMMU finished initialization. C: Just before 21:00.0 When the first kernel crashed, then the dump kernel will boot. Then there comes a DMA request on 21:00.0 when durting A to C. And this will cause this error. If I clear the root entry table when iommu structure is allocted, this error will not happen during A to B, but still can be seen during B and C. I guess the cause is the un-expected DMA request. I will apply Bill Sumner's patch to see whether it will cause the errors disappear. -- Zhenhua On 08/19/2014 07:02 PM, Joerg Roedel wrote: On Mon, Aug 18, 2014 at 11:27:01PM +, Li, Zhen-Hua wrote: : [fault reason 01] Present bit in root entry is clear It appears when iommu initializing in the kdump kernel. Hmm, do you have an explanation how this can happen? From how I read the code, the kdump kernel disables translation on the IOMMU, then sets a new root entry, and then re-enabled translation. To me it looks like there is no point in time where translation is enabled and the root-entry is clear (present-bit==0). But obviously I am missing something if you see the message above. Btw, have you looked into this patch-set posted earlier this year: https://lkml.org/lkml/2014/4/24/836 It approaches the same problem-space, but also cares about in-flight DMA. Joerg -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH 1/1] iommu/vt-d : clear old root entry for dump kernel
On my system, error message: [4.322008] dmar: DRHD: handling fault status reg 2 [4.327484] dmar: DMAR:[DMA Read] Request device [21:00.0] fault addr fff66000 [4.327484] DMAR:[fault reason 01] Present bit in root entry is clear fault happens on device : 21:00.0 To describe this problem clearly, we mark two time points: A: Just before dump kernel init the DMAR/IOMMU structures. B: Just after DMAR/IOMMU finished initialization. C: Just before 21:00.0 When the first kernel crashed, then the dump kernel will boot. Then there comes a DMA request on 21:00.0 when durting A to C. And this will cause this error. If I clear the root entry table when iommu structure is allocted, this error will not happen during A to B, but still can be seen during B and C. I guess the cause is the un-expected DMA request. I will apply Bill Sumner's patch to see whether it will cause the errors disappear. -- Zhenhua On 08/19/2014 07:02 PM, Joerg Roedel wrote: On Mon, Aug 18, 2014 at 11:27:01PM +, Li, Zhen-Hua wrote: : [fault reason 01] Present bit in root entry is clear It appears when iommu initializing in the kdump kernel. Hmm, do you have an explanation how this can happen? From how I read the code, the kdump kernel disables translation on the IOMMU, then sets a new root entry, and then re-enabled translation. To me it looks like there is no point in time where translation is enabled and the root-entry is clear (present-bit==0). But obviously I am missing something if you see the message above. Btw, have you looked into this patch-set posted earlier this year: https://lkml.org/lkml/2014/4/24/836 It approaches the same problem-space, but also cares about in-flight DMA. Joerg -- To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH 1/1] iommu/vt-d : clear old root entry for dump kernel
On Mon, Aug 18, 2014 at 11:27:01PM +, Li, Zhen-Hua wrote: > : [fault reason 01] Present bit in root entry is clear > It appears when iommu initializing in the kdump kernel. Hmm, do you have an explanation how this can happen? From how I read the code, the kdump kernel disables translation on the IOMMU, then sets a new root entry, and then re-enabled translation. To me it looks like there is no point in time where translation is enabled and the root-entry is clear (present-bit==0). But obviously I am missing something if you see the message above. Btw, have you looked into this patch-set posted earlier this year: https://lkml.org/lkml/2014/4/24/836 It approaches the same problem-space, but also cares about in-flight DMA. Joerg -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH 1/1] iommu/vt-d : clear old root entry for dump kernel
On Mon, Aug 18, 2014 at 11:27:01PM +, Li, Zhen-Hua wrote: : [fault reason 01] Present bit in root entry is clear It appears when iommu initializing in the kdump kernel. Hmm, do you have an explanation how this can happen? From how I read the code, the kdump kernel disables translation on the IOMMU, then sets a new root entry, and then re-enabled translation. To me it looks like there is no point in time where translation is enabled and the root-entry is clear (present-bit==0). But obviously I am missing something if you see the message above. Btw, have you looked into this patch-set posted earlier this year: https://lkml.org/lkml/2014/4/24/836 It approaches the same problem-space, but also cares about in-flight DMA. Joerg -- To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH 1/1] iommu/vt-d : clear old root entry for dump kernel
I found there are more data need to be cleared for the dump kernel. So please ignore this patch, I will send out another one. Thanks Zhenhua On 08/19/2014 07:59 AM, Li, Zhen-Hua wrote: My debugging result is this: 1. Clear the old root entry table, dump kernel will choose another memory region for root entry. 2. Do NOT clear the old root entry, when dump kernel initializing the iommu data structure, it will allocate memory for root entry, this is different from the old address. If not clear old entry , the error message appears before dump kernel finishes the iommu init works, and also appears in other places(before device inits). If I clear the old root entry, the error message disappears before iommu init work finish, but still appears in other places. -Original Message- From: Li, Zhen-Hua Sent: Tuesday, August 19, 2014 7:48 AM To: Li, Zhen-Hua; Joerg Roedel Cc: David Woodhouse; io...@lists.linux-foundation.org; linux-kernel@vger.kernel.org Subject: RE: [PATCH 1/1] iommu/vt-d : clear old root entry for dump kernel When the dump kernel boots, it will initialize iommu again, and the root entry will be allocted in another memory region. That means, no matter kernel clears the old root entry table or not, the dump kernel will use another memory region when iommu initializing. -Original Message- From: Li, Zhen-Hua Sent: Tuesday, August 19, 2014 7:27 AM To: 'Joerg Roedel' Cc: David Woodhouse; io...@lists.linux-foundation.org; linux-kernel@vger.kernel.org Subject: RE: [PATCH 1/1] iommu/vt-d : clear old root entry for dump kernel : [fault reason 01] Present bit in root entry is clear It appears when iommu initializing in the kdump kernel. -Original Message- From: Joerg Roedel [mailto:j...@8bytes.org] Sent: Tuesday, August 19, 2014 7:23 AM To: Li, Zhen-Hua Cc: David Woodhouse; io...@lists.linux-foundation.org; linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/1] iommu/vt-d : clear old root entry for dump kernel On Mon, Aug 18, 2014 at 11:01:56PM +, Li, Zhen-Hua wrote: There is a bug when Linux running on an HP large system: when kdump kernel runs, the hardware is still using the old root entry. This causes error message when iommu not finished initialization. What error message are you seeing? When the kdump kernel boots the iommu should be still enabled from the old kernel with the old root-entry. So any in-flight DMA initiated from the old kernel can still pass and there should be no error messages. When you clear the root-entry that in-flight DMA might go to another random location in system memory or just fail, no? Joerg -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
RE: [PATCH 1/1] iommu/vt-d : clear old root entry for dump kernel
My debugging result is this: 1. Clear the old root entry table, dump kernel will choose another memory region for root entry. 2. Do NOT clear the old root entry, when dump kernel initializing the iommu data structure, it will allocate memory for root entry, this is different from the old address. If not clear old entry , the error message appears before dump kernel finishes the iommu init works, and also appears in other places(before device inits). If I clear the old root entry, the error message disappears before iommu init work finish, but still appears in other places. -Original Message- From: Li, Zhen-Hua Sent: Tuesday, August 19, 2014 7:48 AM To: Li, Zhen-Hua; Joerg Roedel Cc: David Woodhouse; io...@lists.linux-foundation.org; linux-kernel@vger.kernel.org Subject: RE: [PATCH 1/1] iommu/vt-d : clear old root entry for dump kernel When the dump kernel boots, it will initialize iommu again, and the root entry will be allocted in another memory region. That means, no matter kernel clears the old root entry table or not, the dump kernel will use another memory region when iommu initializing. -Original Message- From: Li, Zhen-Hua Sent: Tuesday, August 19, 2014 7:27 AM To: 'Joerg Roedel' Cc: David Woodhouse; io...@lists.linux-foundation.org; linux-kernel@vger.kernel.org Subject: RE: [PATCH 1/1] iommu/vt-d : clear old root entry for dump kernel : [fault reason 01] Present bit in root entry is clear It appears when iommu initializing in the kdump kernel. -Original Message- From: Joerg Roedel [mailto:j...@8bytes.org] Sent: Tuesday, August 19, 2014 7:23 AM To: Li, Zhen-Hua Cc: David Woodhouse; io...@lists.linux-foundation.org; linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/1] iommu/vt-d : clear old root entry for dump kernel On Mon, Aug 18, 2014 at 11:01:56PM +, Li, Zhen-Hua wrote: > There is a bug when Linux running on an HP large system: > when kdump kernel runs, the hardware is still using the old > root entry. This causes error message when iommu not finished initialization. What error message are you seeing? When the kdump kernel boots the iommu should be still enabled from the old kernel with the old root-entry. So any in-flight DMA initiated from the old kernel can still pass and there should be no error messages. When you clear the root-entry that in-flight DMA might go to another random location in system memory or just fail, no? Joerg -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
RE: [PATCH 1/1] iommu/vt-d : clear old root entry for dump kernel
When the dump kernel boots, it will initialize iommu again, and the root entry will be allocted in another memory region. That means, no matter kernel clears the old root entry table or not, the dump kernel will use another memory region when iommu initializing. -Original Message- From: Li, Zhen-Hua Sent: Tuesday, August 19, 2014 7:27 AM To: 'Joerg Roedel' Cc: David Woodhouse; io...@lists.linux-foundation.org; linux-kernel@vger.kernel.org Subject: RE: [PATCH 1/1] iommu/vt-d : clear old root entry for dump kernel : [fault reason 01] Present bit in root entry is clear It appears when iommu initializing in the kdump kernel. -Original Message- From: Joerg Roedel [mailto:j...@8bytes.org] Sent: Tuesday, August 19, 2014 7:23 AM To: Li, Zhen-Hua Cc: David Woodhouse; io...@lists.linux-foundation.org; linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/1] iommu/vt-d : clear old root entry for dump kernel On Mon, Aug 18, 2014 at 11:01:56PM +, Li, Zhen-Hua wrote: > There is a bug when Linux running on an HP large system: > when kdump kernel runs, the hardware is still using the old > root entry. This causes error message when iommu not finished initialization. What error message are you seeing? When the kdump kernel boots the iommu should be still enabled from the old kernel with the old root-entry. So any in-flight DMA initiated from the old kernel can still pass and there should be no error messages. When you clear the root-entry that in-flight DMA might go to another random location in system memory or just fail, no? Joerg -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
RE: [PATCH 1/1] iommu/vt-d : clear old root entry for dump kernel
: [fault reason 01] Present bit in root entry is clear It appears when iommu initializing in the kdump kernel. -Original Message- From: Joerg Roedel [mailto:j...@8bytes.org] Sent: Tuesday, August 19, 2014 7:23 AM To: Li, Zhen-Hua Cc: David Woodhouse; io...@lists.linux-foundation.org; linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/1] iommu/vt-d : clear old root entry for dump kernel On Mon, Aug 18, 2014 at 11:01:56PM +, Li, Zhen-Hua wrote: > There is a bug when Linux running on an HP large system: > when kdump kernel runs, the hardware is still using the old > root entry. This causes error message when iommu not finished initialization. What error message are you seeing? When the kdump kernel boots the iommu should be still enabled from the old kernel with the old root-entry. So any in-flight DMA initiated from the old kernel can still pass and there should be no error messages. When you clear the root-entry that in-flight DMA might go to another random location in system memory or just fail, no? Joerg -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH 1/1] iommu/vt-d : clear old root entry for dump kernel
On Mon, Aug 18, 2014 at 11:01:56PM +, Li, Zhen-Hua wrote: > There is a bug when Linux running on an HP large system: > when kdump kernel runs, the hardware is still using the old > root entry. This causes error message when iommu not finished initialization. What error message are you seeing? When the kdump kernel boots the iommu should be still enabled from the old kernel with the old root-entry. So any in-flight DMA initiated from the old kernel can still pass and there should be no error messages. When you clear the root-entry that in-flight DMA might go to another random location in system memory or just fail, no? Joerg -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
RE: [PATCH 1/1] iommu/vt-d : clear old root entry for dump kernel
There is a bug when Linux running on an HP large system:
when kdump kernel runs, the hardware is still using the old
root entry. This causes error message when iommu not finished initialization.
-Original Message-
From: Li, Zhen-Hua
Sent: Monday, August 18, 2014 4:59 PM
To: David Woodhouse; Joerg Roedel; io...@lists.linux-foundation.org;
linux-kernel@vger.kernel.org
Cc: Li, Zhen-Hua
Subject: [PATCH 1/1] iommu/vt-d : clear old root entry for dump kernel
If intel_iommu is enabled, when kdump kernel boots, the old root entry
should be cleared, otherwise it may cause DMAR error.
To make it works for more enviroments, this patch does not use
is_kdump_kernel() to check it, but reads the register to check whether
hardware is using old root entry.
Signed-off-by: Li, Zhen-Hua
---
drivers/iommu/dmar.c | 31 +++
1 file changed, 31 insertions(+)
diff --git a/drivers/iommu/dmar.c b/drivers/iommu/dmar.c
index 60ab474..7b4fa90 100644
--- a/drivers/iommu/dmar.c
+++ b/drivers/iommu/dmar.c
@@ -66,6 +66,8 @@ static int dmar_dev_scope_status = 1;
static int alloc_iommu(struct dmar_drhd_unit *drhd);
static void free_iommu(struct intel_iommu *iommu);
+static int iommu_check_root_entry(struct intel_iommu *iommu);
+
static void __init dmar_register_drhd_unit(struct dmar_drhd_unit *drhd)
{
/*
@@ -987,6 +989,8 @@ static int alloc_iommu(struct dmar_drhd_unit *drhd)
intel_iommu_groups,
iommu->name);
+ iommu_check_root_entry(iommu);
+
return 0;
err_unmap:
@@ -1666,5 +1670,32 @@ static int __init dmar_free_unused_resources(void)
return 0;
}
+static int iommu_check_root_entry(struct intel_iommu *iommu)
+{
+ u64 re_pa;
+
+ re_pa = dmar_readq(iommu->reg + DMAR_RTADDR_REG);
+
+ /* This only works for hardware error and kdump kernel */
+ if (unlikely(re_pa != 0)) {
+ u32 sts;
+ unsigned long flag;
+
+ raw_spin_lock_irqsave(>register_lock, flag);
+ dmar_writeq(iommu->reg + DMAR_RTADDR_REG, 0);
+
+ writel(iommu->gcmd | DMA_GCMD_SRTP, iommu->reg + DMAR_GCMD_REG);
+
+ /* Make sure hardware complete it */
+ IOMMU_WAIT_OP(iommu, DMAR_GSTS_REG,
+ readl, (sts & DMA_GSTS_RTPS), sts);
+
+ raw_spin_unlock_irqrestore(>register_lock, flag);
+
+ }
+
+ return 0;
+}
+
late_initcall(dmar_free_unused_resources);
IOMMU_INIT_POST(detect_intel_iommu);
--
2.0.0-rc0
--
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the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
[PATCH 1/1] iommu/vt-d : clear old root entry for dump kernel
If intel_iommu is enabled, when kdump kernel boots, the old root entry
should be cleared, otherwise it may cause DMAR error.
To make it works for more enviroments, this patch does not use
is_kdump_kernel() to check it, but reads the register to check whether
hardware is using old root entry.
Signed-off-by: Li, Zhen-Hua
---
drivers/iommu/dmar.c | 31 +++
1 file changed, 31 insertions(+)
diff --git a/drivers/iommu/dmar.c b/drivers/iommu/dmar.c
index 60ab474..7b4fa90 100644
--- a/drivers/iommu/dmar.c
+++ b/drivers/iommu/dmar.c
@@ -66,6 +66,8 @@ static int dmar_dev_scope_status = 1;
static int alloc_iommu(struct dmar_drhd_unit *drhd);
static void free_iommu(struct intel_iommu *iommu);
+static int iommu_check_root_entry(struct intel_iommu *iommu);
+
static void __init dmar_register_drhd_unit(struct dmar_drhd_unit *drhd)
{
/*
@@ -987,6 +989,8 @@ static int alloc_iommu(struct dmar_drhd_unit *drhd)
intel_iommu_groups,
iommu->name);
+ iommu_check_root_entry(iommu);
+
return 0;
err_unmap:
@@ -1666,5 +1670,32 @@ static int __init dmar_free_unused_resources(void)
return 0;
}
+static int iommu_check_root_entry(struct intel_iommu *iommu)
+{
+ u64 re_pa;
+
+ re_pa = dmar_readq(iommu->reg + DMAR_RTADDR_REG);
+
+ /* This only works for hardware error and kdump kernel */
+ if (unlikely(re_pa != 0)) {
+ u32 sts;
+ unsigned long flag;
+
+ raw_spin_lock_irqsave(>register_lock, flag);
+ dmar_writeq(iommu->reg + DMAR_RTADDR_REG, 0);
+
+ writel(iommu->gcmd | DMA_GCMD_SRTP, iommu->reg + DMAR_GCMD_REG);
+
+ /* Make sure hardware complete it */
+ IOMMU_WAIT_OP(iommu, DMAR_GSTS_REG,
+ readl, (sts & DMA_GSTS_RTPS), sts);
+
+ raw_spin_unlock_irqrestore(>register_lock, flag);
+
+ }
+
+ return 0;
+}
+
late_initcall(dmar_free_unused_resources);
IOMMU_INIT_POST(detect_intel_iommu);
--
2.0.0-rc0
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
[PATCH 1/1] iommu/vt-d : clear old root entry for dump kernel
If intel_iommu is enabled, when kdump kernel boots, the old root entry
should be cleared, otherwise it may cause DMAR error.
To make it works for more enviroments, this patch does not use
is_kdump_kernel() to check it, but reads the register to check whether
hardware is using old root entry.
Signed-off-by: Li, Zhen-Hua zhen-h...@hp.com
---
drivers/iommu/dmar.c | 31 +++
1 file changed, 31 insertions(+)
diff --git a/drivers/iommu/dmar.c b/drivers/iommu/dmar.c
index 60ab474..7b4fa90 100644
--- a/drivers/iommu/dmar.c
+++ b/drivers/iommu/dmar.c
@@ -66,6 +66,8 @@ static int dmar_dev_scope_status = 1;
static int alloc_iommu(struct dmar_drhd_unit *drhd);
static void free_iommu(struct intel_iommu *iommu);
+static int iommu_check_root_entry(struct intel_iommu *iommu);
+
static void __init dmar_register_drhd_unit(struct dmar_drhd_unit *drhd)
{
/*
@@ -987,6 +989,8 @@ static int alloc_iommu(struct dmar_drhd_unit *drhd)
intel_iommu_groups,
iommu-name);
+ iommu_check_root_entry(iommu);
+
return 0;
err_unmap:
@@ -1666,5 +1670,32 @@ static int __init dmar_free_unused_resources(void)
return 0;
}
+static int iommu_check_root_entry(struct intel_iommu *iommu)
+{
+ u64 re_pa;
+
+ re_pa = dmar_readq(iommu-reg + DMAR_RTADDR_REG);
+
+ /* This only works for hardware error and kdump kernel */
+ if (unlikely(re_pa != 0)) {
+ u32 sts;
+ unsigned long flag;
+
+ raw_spin_lock_irqsave(iommu-register_lock, flag);
+ dmar_writeq(iommu-reg + DMAR_RTADDR_REG, 0);
+
+ writel(iommu-gcmd | DMA_GCMD_SRTP, iommu-reg + DMAR_GCMD_REG);
+
+ /* Make sure hardware complete it */
+ IOMMU_WAIT_OP(iommu, DMAR_GSTS_REG,
+ readl, (sts DMA_GSTS_RTPS), sts);
+
+ raw_spin_unlock_irqrestore(iommu-register_lock, flag);
+
+ }
+
+ return 0;
+}
+
late_initcall(dmar_free_unused_resources);
IOMMU_INIT_POST(detect_intel_iommu);
--
2.0.0-rc0
--
To unsubscribe from this list: send the line unsubscribe linux-kernel in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
RE: [PATCH 1/1] iommu/vt-d : clear old root entry for dump kernel
There is a bug when Linux running on an HP large system:
when kdump kernel runs, the hardware is still using the old
root entry. This causes error message when iommu not finished initialization.
-Original Message-
From: Li, Zhen-Hua
Sent: Monday, August 18, 2014 4:59 PM
To: David Woodhouse; Joerg Roedel; io...@lists.linux-foundation.org;
linux-kernel@vger.kernel.org
Cc: Li, Zhen-Hua
Subject: [PATCH 1/1] iommu/vt-d : clear old root entry for dump kernel
If intel_iommu is enabled, when kdump kernel boots, the old root entry
should be cleared, otherwise it may cause DMAR error.
To make it works for more enviroments, this patch does not use
is_kdump_kernel() to check it, but reads the register to check whether
hardware is using old root entry.
Signed-off-by: Li, Zhen-Hua zhen-h...@hp.com
---
drivers/iommu/dmar.c | 31 +++
1 file changed, 31 insertions(+)
diff --git a/drivers/iommu/dmar.c b/drivers/iommu/dmar.c
index 60ab474..7b4fa90 100644
--- a/drivers/iommu/dmar.c
+++ b/drivers/iommu/dmar.c
@@ -66,6 +66,8 @@ static int dmar_dev_scope_status = 1;
static int alloc_iommu(struct dmar_drhd_unit *drhd);
static void free_iommu(struct intel_iommu *iommu);
+static int iommu_check_root_entry(struct intel_iommu *iommu);
+
static void __init dmar_register_drhd_unit(struct dmar_drhd_unit *drhd)
{
/*
@@ -987,6 +989,8 @@ static int alloc_iommu(struct dmar_drhd_unit *drhd)
intel_iommu_groups,
iommu-name);
+ iommu_check_root_entry(iommu);
+
return 0;
err_unmap:
@@ -1666,5 +1670,32 @@ static int __init dmar_free_unused_resources(void)
return 0;
}
+static int iommu_check_root_entry(struct intel_iommu *iommu)
+{
+ u64 re_pa;
+
+ re_pa = dmar_readq(iommu-reg + DMAR_RTADDR_REG);
+
+ /* This only works for hardware error and kdump kernel */
+ if (unlikely(re_pa != 0)) {
+ u32 sts;
+ unsigned long flag;
+
+ raw_spin_lock_irqsave(iommu-register_lock, flag);
+ dmar_writeq(iommu-reg + DMAR_RTADDR_REG, 0);
+
+ writel(iommu-gcmd | DMA_GCMD_SRTP, iommu-reg + DMAR_GCMD_REG);
+
+ /* Make sure hardware complete it */
+ IOMMU_WAIT_OP(iommu, DMAR_GSTS_REG,
+ readl, (sts DMA_GSTS_RTPS), sts);
+
+ raw_spin_unlock_irqrestore(iommu-register_lock, flag);
+
+ }
+
+ return 0;
+}
+
late_initcall(dmar_free_unused_resources);
IOMMU_INIT_POST(detect_intel_iommu);
--
2.0.0-rc0
--
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Re: [PATCH 1/1] iommu/vt-d : clear old root entry for dump kernel
On Mon, Aug 18, 2014 at 11:01:56PM +, Li, Zhen-Hua wrote: There is a bug when Linux running on an HP large system: when kdump kernel runs, the hardware is still using the old root entry. This causes error message when iommu not finished initialization. What error message are you seeing? When the kdump kernel boots the iommu should be still enabled from the old kernel with the old root-entry. So any in-flight DMA initiated from the old kernel can still pass and there should be no error messages. When you clear the root-entry that in-flight DMA might go to another random location in system memory or just fail, no? Joerg -- To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
RE: [PATCH 1/1] iommu/vt-d : clear old root entry for dump kernel
: [fault reason 01] Present bit in root entry is clear It appears when iommu initializing in the kdump kernel. -Original Message- From: Joerg Roedel [mailto:j...@8bytes.org] Sent: Tuesday, August 19, 2014 7:23 AM To: Li, Zhen-Hua Cc: David Woodhouse; io...@lists.linux-foundation.org; linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/1] iommu/vt-d : clear old root entry for dump kernel On Mon, Aug 18, 2014 at 11:01:56PM +, Li, Zhen-Hua wrote: There is a bug when Linux running on an HP large system: when kdump kernel runs, the hardware is still using the old root entry. This causes error message when iommu not finished initialization. What error message are you seeing? When the kdump kernel boots the iommu should be still enabled from the old kernel with the old root-entry. So any in-flight DMA initiated from the old kernel can still pass and there should be no error messages. When you clear the root-entry that in-flight DMA might go to another random location in system memory or just fail, no? Joerg -- To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
RE: [PATCH 1/1] iommu/vt-d : clear old root entry for dump kernel
When the dump kernel boots, it will initialize iommu again, and the root entry will be allocted in another memory region. That means, no matter kernel clears the old root entry table or not, the dump kernel will use another memory region when iommu initializing. -Original Message- From: Li, Zhen-Hua Sent: Tuesday, August 19, 2014 7:27 AM To: 'Joerg Roedel' Cc: David Woodhouse; io...@lists.linux-foundation.org; linux-kernel@vger.kernel.org Subject: RE: [PATCH 1/1] iommu/vt-d : clear old root entry for dump kernel : [fault reason 01] Present bit in root entry is clear It appears when iommu initializing in the kdump kernel. -Original Message- From: Joerg Roedel [mailto:j...@8bytes.org] Sent: Tuesday, August 19, 2014 7:23 AM To: Li, Zhen-Hua Cc: David Woodhouse; io...@lists.linux-foundation.org; linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/1] iommu/vt-d : clear old root entry for dump kernel On Mon, Aug 18, 2014 at 11:01:56PM +, Li, Zhen-Hua wrote: There is a bug when Linux running on an HP large system: when kdump kernel runs, the hardware is still using the old root entry. This causes error message when iommu not finished initialization. What error message are you seeing? When the kdump kernel boots the iommu should be still enabled from the old kernel with the old root-entry. So any in-flight DMA initiated from the old kernel can still pass and there should be no error messages. When you clear the root-entry that in-flight DMA might go to another random location in system memory or just fail, no? Joerg -- To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
RE: [PATCH 1/1] iommu/vt-d : clear old root entry for dump kernel
My debugging result is this: 1. Clear the old root entry table, dump kernel will choose another memory region for root entry. 2. Do NOT clear the old root entry, when dump kernel initializing the iommu data structure, it will allocate memory for root entry, this is different from the old address. If not clear old entry , the error message appears before dump kernel finishes the iommu init works, and also appears in other places(before device inits). If I clear the old root entry, the error message disappears before iommu init work finish, but still appears in other places. -Original Message- From: Li, Zhen-Hua Sent: Tuesday, August 19, 2014 7:48 AM To: Li, Zhen-Hua; Joerg Roedel Cc: David Woodhouse; io...@lists.linux-foundation.org; linux-kernel@vger.kernel.org Subject: RE: [PATCH 1/1] iommu/vt-d : clear old root entry for dump kernel When the dump kernel boots, it will initialize iommu again, and the root entry will be allocted in another memory region. That means, no matter kernel clears the old root entry table or not, the dump kernel will use another memory region when iommu initializing. -Original Message- From: Li, Zhen-Hua Sent: Tuesday, August 19, 2014 7:27 AM To: 'Joerg Roedel' Cc: David Woodhouse; io...@lists.linux-foundation.org; linux-kernel@vger.kernel.org Subject: RE: [PATCH 1/1] iommu/vt-d : clear old root entry for dump kernel : [fault reason 01] Present bit in root entry is clear It appears when iommu initializing in the kdump kernel. -Original Message- From: Joerg Roedel [mailto:j...@8bytes.org] Sent: Tuesday, August 19, 2014 7:23 AM To: Li, Zhen-Hua Cc: David Woodhouse; io...@lists.linux-foundation.org; linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/1] iommu/vt-d : clear old root entry for dump kernel On Mon, Aug 18, 2014 at 11:01:56PM +, Li, Zhen-Hua wrote: There is a bug when Linux running on an HP large system: when kdump kernel runs, the hardware is still using the old root entry. This causes error message when iommu not finished initialization. What error message are you seeing? When the kdump kernel boots the iommu should be still enabled from the old kernel with the old root-entry. So any in-flight DMA initiated from the old kernel can still pass and there should be no error messages. When you clear the root-entry that in-flight DMA might go to another random location in system memory or just fail, no? Joerg -- To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH 1/1] iommu/vt-d : clear old root entry for dump kernel
I found there are more data need to be cleared for the dump kernel. So please ignore this patch, I will send out another one. Thanks Zhenhua On 08/19/2014 07:59 AM, Li, Zhen-Hua wrote: My debugging result is this: 1. Clear the old root entry table, dump kernel will choose another memory region for root entry. 2. Do NOT clear the old root entry, when dump kernel initializing the iommu data structure, it will allocate memory for root entry, this is different from the old address. If not clear old entry , the error message appears before dump kernel finishes the iommu init works, and also appears in other places(before device inits). If I clear the old root entry, the error message disappears before iommu init work finish, but still appears in other places. -Original Message- From: Li, Zhen-Hua Sent: Tuesday, August 19, 2014 7:48 AM To: Li, Zhen-Hua; Joerg Roedel Cc: David Woodhouse; io...@lists.linux-foundation.org; linux-kernel@vger.kernel.org Subject: RE: [PATCH 1/1] iommu/vt-d : clear old root entry for dump kernel When the dump kernel boots, it will initialize iommu again, and the root entry will be allocted in another memory region. That means, no matter kernel clears the old root entry table or not, the dump kernel will use another memory region when iommu initializing. -Original Message- From: Li, Zhen-Hua Sent: Tuesday, August 19, 2014 7:27 AM To: 'Joerg Roedel' Cc: David Woodhouse; io...@lists.linux-foundation.org; linux-kernel@vger.kernel.org Subject: RE: [PATCH 1/1] iommu/vt-d : clear old root entry for dump kernel : [fault reason 01] Present bit in root entry is clear It appears when iommu initializing in the kdump kernel. -Original Message- From: Joerg Roedel [mailto:j...@8bytes.org] Sent: Tuesday, August 19, 2014 7:23 AM To: Li, Zhen-Hua Cc: David Woodhouse; io...@lists.linux-foundation.org; linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/1] iommu/vt-d : clear old root entry for dump kernel On Mon, Aug 18, 2014 at 11:01:56PM +, Li, Zhen-Hua wrote: There is a bug when Linux running on an HP large system: when kdump kernel runs, the hardware is still using the old root entry. This causes error message when iommu not finished initialization. What error message are you seeing? When the kdump kernel boots the iommu should be still enabled from the old kernel with the old root-entry. So any in-flight DMA initiated from the old kernel can still pass and there should be no error messages. When you clear the root-entry that in-flight DMA might go to another random location in system memory or just fail, no? Joerg -- To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
