This patch makes iommu/amd call report_iommu_fault() when an I/O page
fault occurs, which has two effects:
1) It allows device drivers to register a callback to be notified of
I/O page faults, via the iommu_set_fault_handler() API.
2) It triggers the io_page_fault tracepoint in report_iommu_fault()
when an I/O page fault occurs.
The latter point is the main aim of this patch, as it allows
rasdaemon-like daemons to be notified of I/O page faults, and to
possibly initiate corrective action in response.
A number of other IOMMU drivers already use report_iommu_fault(), and
I/O page faults on those IOMMUs therefore already trigger this
tracepoint -- but this isn't yet the case for AMD-Vi and Intel DMAR.
The AMD IOMMU specification suggests that the bit in an I/O page fault
event log entry that signals whether an I/O page fault was for a read
request or for a write request is only meaningful when the faulting
access was to a present page, but some testing on a Ryzen 3700X suggests
that this bit encodes the correct value even for I/O page faults to
non-present pages, and therefore, this patch passes the R/W information
up the stack even for I/O page faults to non-present pages.
Signed-off-by: Lennert Buytenhek
---
Tested on v5.15-rc2 on a Ryzen 3700X, where it has the desired effect.
Changes for v4:
- Unconditionally pass through RW bit, after testing that suggests
that this bit is reliable even for I/O page faults to non-present
pages.
Changes for v3:
- Test fault flags via macros. (Suggested by Suravee Suthikulpanit.)
Changes for v2:
- Don't call report_iommu_fault() for IRQ remapping faults.
(Suggested by Joerg Roedel.)
drivers/iommu/amd/amd_iommu_types.h | 2 ++
drivers/iommu/amd/iommu.c | 19 +++
2 files changed, 21 insertions(+)
diff --git a/drivers/iommu/amd/amd_iommu_types.h
b/drivers/iommu/amd/amd_iommu_types.h
index 8dbe61e2b3c1..867535eb0ce9 100644
--- a/drivers/iommu/amd/amd_iommu_types.h
+++ b/drivers/iommu/amd/amd_iommu_types.h
@@ -138,6 +138,8 @@
#define EVENT_DOMID_MASK_HI0xf
#define EVENT_FLAGS_MASK 0xfff
#define EVENT_FLAGS_SHIFT 0x10
+#define EVENT_FLAG_RW 0x020
+#define EVENT_FLAG_I 0x008
/* feature control bits */
#define CONTROL_IOMMU_EN0x00ULL
diff --git a/drivers/iommu/amd/iommu.c b/drivers/iommu/amd/iommu.c
index 1722bb161841..7b592aba06f5 100644
--- a/drivers/iommu/amd/iommu.c
+++ b/drivers/iommu/amd/iommu.c
@@ -473,6 +473,12 @@ static void amd_iommu_report_rmp_fault(volatile u32 *event)
pci_dev_put(pdev);
}
+#define IS_IOMMU_MEM_TRANSACTION(flags)\
+ (((flags) & EVENT_FLAG_I) == 0)
+
+#define IS_WRITE_REQUEST(flags)\
+ ((flags) & EVENT_FLAG_RW)
+
static void amd_iommu_report_page_fault(u16 devid, u16 domain_id,
u64 address, int flags)
{
@@ -484,6 +490,18 @@ static void amd_iommu_report_page_fault(u16 devid, u16
domain_id,
if (pdev)
dev_data = dev_iommu_priv_get(&pdev->dev);
+ /*
+* If this is a DMA fault (for which the I(nterrupt) bit will
+* be unset), allow report_iommu_fault() to prevent logging it.
+*/
+ if (dev_data && IS_IOMMU_MEM_TRANSACTION(flags)) {
+ if (!report_iommu_fault(&dev_data->domain->domain,
+ &pdev->dev, address,
+ IS_WRITE_REQUEST(flags) ?
+ IOMMU_FAULT_WRITE : IOMMU_FAULT_READ))
+ goto out;
+ }
+
if (dev_data) {
if (__ratelimit(&dev_data->rs)) {
pci_err(pdev, "Event logged [IO_PAGE_FAULT
domain=0x%04x address=0x%llx flags=0x%04x]\n",
@@ -495,6 +513,7 @@ static void amd_iommu_report_page_fault(u16 devid, u16
domain_id,
domain_id, address, flags);
}
+out:
if (pdev)
pci_dev_put(pdev);
}
--
2.31.1
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