Commit 9f78e446 authored by Lennert Buytenhek's avatar Lennert Buytenhek Committed by Joerg Roedel
Browse files

iommu/amd: Use report_iommu_fault() 



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: default avatarLennert Buytenhek <buytenh@arista.com>
Link: https://lore.kernel.org/r/YVLyBW97vZLpOaAp@wantstofly.org


Signed-off-by: default avatarJoerg Roedel <jroedel@suse.de>
parent 5816b3e6

drivers/iommu/amd/amd_iommu_types.h

+2 −0
Original line number Diff line number Diff line
@@ -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

drivers/iommu/amd/iommu.c

+21 −0
Original line number Diff line number Diff line
@@ -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);

}