Re: [PATCH 3/5] iommu/vt-d: Check domain force_snooping against attached devices
On 2022/5/3 05:31, Jacob Pan wrote:
Hi BaoLu,
Hi Jacob,
On Sun, 1 May 2022 19:24:32 +0800, Lu Baolu
wrote:
As domain->force_snooping only impacts the devices attached with the
domain, there's no need to check against all IOMMU units. At the same
time, for a brand new domain (hasn't been attached to any device), the
force_snooping field could be set, but the attach_dev callback will
return failure if it wants to attach to a device which IOMMU has no
snoop control capability.
Signed-off-by: Lu Baolu
---
drivers/iommu/intel/pasid.h | 2 ++
drivers/iommu/intel/iommu.c | 50 -
drivers/iommu/intel/pasid.c | 18 +
3 files changed, 69 insertions(+), 1 deletion(-)
diff --git a/drivers/iommu/intel/pasid.h b/drivers/iommu/intel/pasid.h
index ab4408c824a5..583ea67fc783 100644
--- a/drivers/iommu/intel/pasid.h
+++ b/drivers/iommu/intel/pasid.h
@@ -123,4 +123,6 @@ void intel_pasid_tear_down_entry(struct intel_iommu
*iommu, bool fault_ignore);
int vcmd_alloc_pasid(struct intel_iommu *iommu, u32 *pasid);
void vcmd_free_pasid(struct intel_iommu *iommu, u32 pasid);
+void intel_pasid_setup_page_snoop_control(struct intel_iommu *iommu,
+ struct device *dev, u32 pasid);
#endif /* __INTEL_PASID_H */
diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
index 98050943d863..3c1c228f9031 100644
--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -4554,13 +4554,61 @@ static phys_addr_t
intel_iommu_iova_to_phys(struct iommu_domain *domain, return phys;
}
+static bool domain_support_force_snooping(struct dmar_domain *domain)
+{
+ struct device_domain_info *info;
+ unsigned long flags;
+ bool support = true;
+
+ spin_lock_irqsave(_domain_lock, flags);
+ if (list_empty(>devices))
+ goto out;
+
+ list_for_each_entry(info, >devices, link) {
+ if (!ecap_sc_support(info->iommu->ecap)) {
+ support = false;
+ break;
+ }
+ }
why not just check the flag dmar_domain->force_snooping? devices wouldn't
be able to attach if !ecap_sc, right?
I should check "dmar_domain->force_snooping" first. If this is the first
time that this flag is about to set, then check the capabilities.
+out:
+ spin_unlock_irqrestore(_domain_lock, flags);
+ return support;
+}
+
+static void domain_set_force_snooping(struct dmar_domain *domain)
+{
+ struct device_domain_info *info;
+ unsigned long flags;
+
+ /*
+* Second level page table supports per-PTE snoop control. The
+* iommu_map() interface will handle this by setting SNP bit.
+*/
+ if (!domain_use_first_level(domain))
+ return;
+
+ spin_lock_irqsave(_domain_lock, flags);
+ if (list_empty(>devices))
+ goto out_unlock;
+
+ list_for_each_entry(info, >devices, link)
+ intel_pasid_setup_page_snoop_control(info->iommu,
info->dev,
+PASID_RID2PASID);
+
I guess other DMA API PASIDs need to have sc bit set as well. I will keep
this in mind for my DMA API PASID patch.
Kernel DMA don't need to set the PGSNP bit. The x86 arch is always DMA
coherent. The force snooping is only needed when the device is
controlled by user space, but the VMM is optimized not to support the
virtualization of the wbinv instruction.
+out_unlock:
+ spin_unlock_irqrestore(_domain_lock, flags);
+}
+
static bool intel_iommu_enforce_cache_coherency(struct iommu_domain
*domain) {
struct dmar_domain *dmar_domain = to_dmar_domain(domain);
- if (!domain_update_iommu_snooping(NULL))
+ if (!domain_support_force_snooping(dmar_domain))
return false;
+
+ domain_set_force_snooping(dmar_domain);
dmar_domain->force_snooping = true;
+
nit: spurious change
I expect a blank line before return in the end.
return true;
}
diff --git a/drivers/iommu/intel/pasid.c b/drivers/iommu/intel/pasid.c
index f8d215d85695..815c744e6a34 100644
--- a/drivers/iommu/intel/pasid.c
+++ b/drivers/iommu/intel/pasid.c
@@ -762,3 +762,21 @@ int intel_pasid_setup_pass_through(struct
intel_iommu *iommu,
return 0;
}
+
+/*
+ * Set the page snoop control for a pasid entry which has been set up.
+ */
+void intel_pasid_setup_page_snoop_control(struct intel_iommu *iommu,
+ struct device *dev, u32 pasid)
+{
+ struct pasid_entry *pte;
+ u16 did;
+
+ pte = intel_pasid_get_entry(dev, pasid);
+ if (WARN_ON(!pte || !pasid_pte_is_present(pte)))
+ return;
+
+ pasid_set_pgsnp(pte);
+ did = pasid_get_domain_id(pte);
+ pasid_flush_caches(iommu, pte, pasid, did);
+}
Thanks,
Jacob
Best regards,
baolu
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Re: [PATCH 3/5] iommu/vt-d: Check domain force_snooping against attached devices
On 2022/5/2 21:17, Jason Gunthorpe wrote:
On Sun, May 01, 2022 at 07:24:32PM +0800, Lu Baolu wrote:
+static bool domain_support_force_snooping(struct dmar_domain *domain)
+{
+ struct device_domain_info *info;
+ unsigned long flags;
+ bool support = true;
+
+ spin_lock_irqsave(_domain_lock, flags);
+ if (list_empty(>devices))
+ goto out;
Why? list_for_each_entry will just do nothing..
Yes. I will remove above two lines.
+ list_for_each_entry(info, >devices, link) {
+ if (!ecap_sc_support(info->iommu->ecap)) {
+ support = false;
+ break;
+ }
+ }
+out:
+ spin_unlock_irqrestore(_domain_lock, flags);
+ return support;
+}
+
+static void domain_set_force_snooping(struct dmar_domain *domain)
+{
+ struct device_domain_info *info;
+ unsigned long flags;
+
+ /*
+* Second level page table supports per-PTE snoop control. The
+* iommu_map() interface will handle this by setting SNP bit.
+*/
+ if (!domain_use_first_level(domain))
+ return;
+
+ spin_lock_irqsave(_domain_lock, flags);
+ if (list_empty(>devices))
+ goto out_unlock;
+
+ list_for_each_entry(info, >devices, link)
+ intel_pasid_setup_page_snoop_control(info->iommu, info->dev,
+PASID_RID2PASID);
+
+out_unlock:
+ spin_unlock_irqrestore(_domain_lock, flags);
+}
+
static bool intel_iommu_enforce_cache_coherency(struct iommu_domain *domain)
{
struct dmar_domain *dmar_domain = to_dmar_domain(domain);
- if (!domain_update_iommu_snooping(NULL))
+ if (!domain_support_force_snooping(dmar_domain))
return false;
Maybe exit early if force_snooping = true?
Yes, should check "force_snooping = true" and return directly if
force_snooping has already been set. As you pointed below, the new
domain_attach should take care of this flag as well. Thanks!
+ domain_set_force_snooping(dmar_domain);
dmar_domain->force_snooping = true;
+
return true;
}
diff --git a/drivers/iommu/intel/pasid.c b/drivers/iommu/intel/pasid.c
index f8d215d85695..815c744e6a34 100644
+++ b/drivers/iommu/intel/pasid.c
@@ -762,3 +762,21 @@ int intel_pasid_setup_pass_through(struct intel_iommu
*iommu,
return 0;
}
+
+/*
+ * Set the page snoop control for a pasid entry which has been set up.
+ */
So the 'first level' is only used with pasid?
Yes. A fake pasid (RID2PASID in spec) is used for legacy transactions
(those w/o pasid).
+void intel_pasid_setup_page_snoop_control(struct intel_iommu *iommu,
+ struct device *dev, u32 pasid)
+{
+ struct pasid_entry *pte;
+ u16 did;
+
+ pte = intel_pasid_get_entry(dev, pasid);
+ if (WARN_ON(!pte || !pasid_pte_is_present(pte)))
+ return;
+
+ pasid_set_pgsnp(pte);
Doesn't this need to be done in other places too, like when a new attach
is made? Patch 5 removed it, but should that be made if
domain->force_snooping?
Yes. I missed this. Will take care of this in the next version.
Jason
Best regards,
baolu
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Re: [PATCH 3/5] iommu/vt-d: Check domain force_snooping against attached devices
Hi BaoLu,
On Sun, 1 May 2022 19:24:32 +0800, Lu Baolu
wrote:
> As domain->force_snooping only impacts the devices attached with the
> domain, there's no need to check against all IOMMU units. At the same
> time, for a brand new domain (hasn't been attached to any device), the
> force_snooping field could be set, but the attach_dev callback will
> return failure if it wants to attach to a device which IOMMU has no
> snoop control capability.
>
> Signed-off-by: Lu Baolu
> ---
> drivers/iommu/intel/pasid.h | 2 ++
> drivers/iommu/intel/iommu.c | 50 -
> drivers/iommu/intel/pasid.c | 18 +
> 3 files changed, 69 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/iommu/intel/pasid.h b/drivers/iommu/intel/pasid.h
> index ab4408c824a5..583ea67fc783 100644
> --- a/drivers/iommu/intel/pasid.h
> +++ b/drivers/iommu/intel/pasid.h
> @@ -123,4 +123,6 @@ void intel_pasid_tear_down_entry(struct intel_iommu
> *iommu, bool fault_ignore);
> int vcmd_alloc_pasid(struct intel_iommu *iommu, u32 *pasid);
> void vcmd_free_pasid(struct intel_iommu *iommu, u32 pasid);
> +void intel_pasid_setup_page_snoop_control(struct intel_iommu *iommu,
> + struct device *dev, u32 pasid);
> #endif /* __INTEL_PASID_H */
> diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
> index 98050943d863..3c1c228f9031 100644
> --- a/drivers/iommu/intel/iommu.c
> +++ b/drivers/iommu/intel/iommu.c
> @@ -4554,13 +4554,61 @@ static phys_addr_t
> intel_iommu_iova_to_phys(struct iommu_domain *domain, return phys;
> }
>
> +static bool domain_support_force_snooping(struct dmar_domain *domain)
> +{
> + struct device_domain_info *info;
> + unsigned long flags;
> + bool support = true;
> +
> + spin_lock_irqsave(_domain_lock, flags);
> + if (list_empty(>devices))
> + goto out;
> +
> + list_for_each_entry(info, >devices, link) {
> + if (!ecap_sc_support(info->iommu->ecap)) {
> + support = false;
> + break;
> + }
> + }
why not just check the flag dmar_domain->force_snooping? devices wouldn't
be able to attach if !ecap_sc, right?
> +out:
> + spin_unlock_irqrestore(_domain_lock, flags);
> + return support;
> +}
> +
> +static void domain_set_force_snooping(struct dmar_domain *domain)
> +{
> + struct device_domain_info *info;
> + unsigned long flags;
> +
> + /*
> + * Second level page table supports per-PTE snoop control. The
> + * iommu_map() interface will handle this by setting SNP bit.
> + */
> + if (!domain_use_first_level(domain))
> + return;
> +
> + spin_lock_irqsave(_domain_lock, flags);
> + if (list_empty(>devices))
> + goto out_unlock;
> +
> + list_for_each_entry(info, >devices, link)
> + intel_pasid_setup_page_snoop_control(info->iommu,
> info->dev,
> + PASID_RID2PASID);
> +
I guess other DMA API PASIDs need to have sc bit set as well. I will keep
this in mind for my DMA API PASID patch.
> +out_unlock:
> + spin_unlock_irqrestore(_domain_lock, flags);
> +}
> +
> static bool intel_iommu_enforce_cache_coherency(struct iommu_domain
> *domain) {
> struct dmar_domain *dmar_domain = to_dmar_domain(domain);
>
> - if (!domain_update_iommu_snooping(NULL))
> + if (!domain_support_force_snooping(dmar_domain))
> return false;
> +
> + domain_set_force_snooping(dmar_domain);
> dmar_domain->force_snooping = true;
> +
nit: spurious change
> return true;
> }
>
> diff --git a/drivers/iommu/intel/pasid.c b/drivers/iommu/intel/pasid.c
> index f8d215d85695..815c744e6a34 100644
> --- a/drivers/iommu/intel/pasid.c
> +++ b/drivers/iommu/intel/pasid.c
> @@ -762,3 +762,21 @@ int intel_pasid_setup_pass_through(struct
> intel_iommu *iommu,
> return 0;
> }
> +
> +/*
> + * Set the page snoop control for a pasid entry which has been set up.
> + */
> +void intel_pasid_setup_page_snoop_control(struct intel_iommu *iommu,
> + struct device *dev, u32 pasid)
> +{
> + struct pasid_entry *pte;
> + u16 did;
> +
> + pte = intel_pasid_get_entry(dev, pasid);
> + if (WARN_ON(!pte || !pasid_pte_is_present(pte)))
> + return;
> +
> + pasid_set_pgsnp(pte);
> + did = pasid_get_domain_id(pte);
> + pasid_flush_caches(iommu, pte, pasid, did);
> +}
Thanks,
Jacob
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Re: [PATCH 3/5] iommu/vt-d: Check domain force_snooping against attached devices
On Sun, May 01, 2022 at 07:24:32PM +0800, Lu Baolu wrote:
> +static bool domain_support_force_snooping(struct dmar_domain *domain)
> +{
> + struct device_domain_info *info;
> + unsigned long flags;
> + bool support = true;
> +
> + spin_lock_irqsave(_domain_lock, flags);
> + if (list_empty(>devices))
> + goto out;
Why? list_for_each_entry will just do nothing..
> + list_for_each_entry(info, >devices, link) {
> + if (!ecap_sc_support(info->iommu->ecap)) {
> + support = false;
> + break;
> + }
> + }
> +out:
> + spin_unlock_irqrestore(_domain_lock, flags);
> + return support;
> +}
> +
> +static void domain_set_force_snooping(struct dmar_domain *domain)
> +{
> + struct device_domain_info *info;
> + unsigned long flags;
> +
> + /*
> + * Second level page table supports per-PTE snoop control. The
> + * iommu_map() interface will handle this by setting SNP bit.
> + */
> + if (!domain_use_first_level(domain))
> + return;
> +
> + spin_lock_irqsave(_domain_lock, flags);
> + if (list_empty(>devices))
> + goto out_unlock;
> +
> + list_for_each_entry(info, >devices, link)
> + intel_pasid_setup_page_snoop_control(info->iommu, info->dev,
> + PASID_RID2PASID);
> +
> +out_unlock:
> + spin_unlock_irqrestore(_domain_lock, flags);
> +}
> +
> static bool intel_iommu_enforce_cache_coherency(struct iommu_domain *domain)
> {
> struct dmar_domain *dmar_domain = to_dmar_domain(domain);
>
> - if (!domain_update_iommu_snooping(NULL))
> + if (!domain_support_force_snooping(dmar_domain))
> return false;
Maybe exit early if force_snooping = true?
> + domain_set_force_snooping(dmar_domain);
> dmar_domain->force_snooping = true;
> +
> return true;
> }
>
> diff --git a/drivers/iommu/intel/pasid.c b/drivers/iommu/intel/pasid.c
> index f8d215d85695..815c744e6a34 100644
> +++ b/drivers/iommu/intel/pasid.c
> @@ -762,3 +762,21 @@ int intel_pasid_setup_pass_through(struct intel_iommu
> *iommu,
>
> return 0;
> }
> +
> +/*
> + * Set the page snoop control for a pasid entry which has been set up.
> + */
So the 'first level' is only used with pasid?
> +void intel_pasid_setup_page_snoop_control(struct intel_iommu *iommu,
> + struct device *dev, u32 pasid)
> +{
> + struct pasid_entry *pte;
> + u16 did;
> +
> + pte = intel_pasid_get_entry(dev, pasid);
> + if (WARN_ON(!pte || !pasid_pte_is_present(pte)))
> + return;
> +
> + pasid_set_pgsnp(pte);
Doesn't this need to be done in other places too, like when a new attach
is made? Patch 5 removed it, but should that be made if
domain->force_snooping?
Jason
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[PATCH 3/5] iommu/vt-d: Check domain force_snooping against attached devices
As domain->force_snooping only impacts the devices attached with the
domain, there's no need to check against all IOMMU units. At the same
time, for a brand new domain (hasn't been attached to any device), the
force_snooping field could be set, but the attach_dev callback will
return failure if it wants to attach to a device which IOMMU has no
snoop control capability.
Signed-off-by: Lu Baolu
---
drivers/iommu/intel/pasid.h | 2 ++
drivers/iommu/intel/iommu.c | 50 -
drivers/iommu/intel/pasid.c | 18 +
3 files changed, 69 insertions(+), 1 deletion(-)
diff --git a/drivers/iommu/intel/pasid.h b/drivers/iommu/intel/pasid.h
index ab4408c824a5..583ea67fc783 100644
--- a/drivers/iommu/intel/pasid.h
+++ b/drivers/iommu/intel/pasid.h
@@ -123,4 +123,6 @@ void intel_pasid_tear_down_entry(struct intel_iommu *iommu,
bool fault_ignore);
int vcmd_alloc_pasid(struct intel_iommu *iommu, u32 *pasid);
void vcmd_free_pasid(struct intel_iommu *iommu, u32 pasid);
+void intel_pasid_setup_page_snoop_control(struct intel_iommu *iommu,
+ struct device *dev, u32 pasid);
#endif /* __INTEL_PASID_H */
diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
index 98050943d863..3c1c228f9031 100644
--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -4554,13 +4554,61 @@ static phys_addr_t intel_iommu_iova_to_phys(struct
iommu_domain *domain,
return phys;
}
+static bool domain_support_force_snooping(struct dmar_domain *domain)
+{
+ struct device_domain_info *info;
+ unsigned long flags;
+ bool support = true;
+
+ spin_lock_irqsave(_domain_lock, flags);
+ if (list_empty(>devices))
+ goto out;
+
+ list_for_each_entry(info, >devices, link) {
+ if (!ecap_sc_support(info->iommu->ecap)) {
+ support = false;
+ break;
+ }
+ }
+out:
+ spin_unlock_irqrestore(_domain_lock, flags);
+ return support;
+}
+
+static void domain_set_force_snooping(struct dmar_domain *domain)
+{
+ struct device_domain_info *info;
+ unsigned long flags;
+
+ /*
+* Second level page table supports per-PTE snoop control. The
+* iommu_map() interface will handle this by setting SNP bit.
+*/
+ if (!domain_use_first_level(domain))
+ return;
+
+ spin_lock_irqsave(_domain_lock, flags);
+ if (list_empty(>devices))
+ goto out_unlock;
+
+ list_for_each_entry(info, >devices, link)
+ intel_pasid_setup_page_snoop_control(info->iommu, info->dev,
+PASID_RID2PASID);
+
+out_unlock:
+ spin_unlock_irqrestore(_domain_lock, flags);
+}
+
static bool intel_iommu_enforce_cache_coherency(struct iommu_domain *domain)
{
struct dmar_domain *dmar_domain = to_dmar_domain(domain);
- if (!domain_update_iommu_snooping(NULL))
+ if (!domain_support_force_snooping(dmar_domain))
return false;
+
+ domain_set_force_snooping(dmar_domain);
dmar_domain->force_snooping = true;
+
return true;
}
diff --git a/drivers/iommu/intel/pasid.c b/drivers/iommu/intel/pasid.c
index f8d215d85695..815c744e6a34 100644
--- a/drivers/iommu/intel/pasid.c
+++ b/drivers/iommu/intel/pasid.c
@@ -762,3 +762,21 @@ int intel_pasid_setup_pass_through(struct intel_iommu
*iommu,
return 0;
}
+
+/*
+ * Set the page snoop control for a pasid entry which has been set up.
+ */
+void intel_pasid_setup_page_snoop_control(struct intel_iommu *iommu,
+ struct device *dev, u32 pasid)
+{
+ struct pasid_entry *pte;
+ u16 did;
+
+ pte = intel_pasid_get_entry(dev, pasid);
+ if (WARN_ON(!pte || !pasid_pte_is_present(pte)))
+ return;
+
+ pasid_set_pgsnp(pte);
+ did = pasid_get_domain_id(pte);
+ pasid_flush_caches(iommu, pte, pasid, did);
+}
--
2.25.1
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