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iommu/amd: Use report_iommu_fault()

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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 <buytenh@arista.com>
Link: https://lore.kernel.org/r/YVLyBW97vZLpOaAp@wantstofly.org
Signed-off-by: Joerg Roedel <jroedel@suse.de>
This commit is contained in:
Lennert Buytenhek 2021-09-28 13:44:21 +03:00 committed by Joerg Roedel
parent 5816b3e657
commit 9f78e446bd
2 changed files with 23 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
drivers/iommu/amd/amd_iommu_types.h
View File

@ -138,6 +138,8 @@
#define EVENT_DOMID_MASK_HI 0xf0000
#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_EN 0x00ULL

21
drivers/iommu/amd/iommu.c
View File

@ -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)
{
@ -485,6 +491,20 @@ static void amd_iommu_report_page_fault(u16 devid, u16 domain_id,
dev_data = dev_iommu_priv_get(&pdev->dev);
if (dev_data) {
/*
* If this is a DMA fault (for which the I(nterrupt)
* bit will be unset), allow report_iommu_fault() to
* prevent logging it.
*/
if (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 (__ratelimit(&dev_data->rs)) {
pci_err(pdev, "Event logged [IO_PAGE_FAULT domain=0x%04x address=0x%llx flags=0x%04x]\n",
domain_id, address, flags);
@ -495,6 +515,7 @@ static void amd_iommu_report_page_fault(u16 devid, u16 domain_id,
domain_id, address, flags);
}
out:
if (pdev)
pci_dev_put(pdev);
}