github-mirror/linux
1
0
Fork 0
mirror of https://github.com/torvalds/linux.git synced 2026-06-04 20:46:48 +02:00
Code Issues Actions Packages Projects Releases Wiki Activity Graph

iommu/amd: Document which IRTE fields amd_iommu_update_ga() can modify

Browse Source 
Add a comment to amd_iommu_update_ga() to document what fields it can
safely modify without issuing an invalidation of the IRTE, and to explain
its role in keeping GA IRTEs up-to-date.

Per page 93 of the IOMMU spec dated Feb 2025:

  When virtual interrupts are enabled by setting MMIO Offset 0018h[GAEn] and
  IRTE[GuestMode=1], IRTE[IsRun], IRTE[Destination], and if present IRTE[GATag],
  are not cached by the IOMMU. Modifications to these fields do not require an
  invalidation of the Interrupt Remapping Table.

Link: https://lore.kernel.org/all/9b7ceea3-8c47-4383-ad9c-1a9bbdc9044a@oracle.com
Cc: Joao Martins <joao.m.martins@oracle.com>
Link: https://lore.kernel.org/r/20250611224604.313496-41-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
This commit is contained in:
Sean Christopherson 2025-06-11 15:45:42 -07:00
parent c3d591c91f
commit 3be405e89f
1 changed files with 12 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

12
drivers/iommu/amd/iommu.c
View File

@ -3986,6 +3986,18 @@ int amd_iommu_create_irq_domain(struct amd_iommu *iommu)
return 0;
}
/*
* Update the pCPU information for an IRTE that is configured to post IRQs to
* a vCPU, without issuing an IOMMU invalidation for the IRTE.
*
* This API is intended to be used when a vCPU is scheduled in/out (or stops
* running for any reason), to do a fast update of IsRun and (conditionally)
* Destination.
*
* Per the IOMMU spec, the Destination, IsRun, and GATag fields are not cached
* and thus don't require an invalidation to ensure the IOMMU consumes fresh
* information.
*/
int amd_iommu_update_ga(int cpu, bool is_run, void *data)
{
struct amd_ir_data *ir_data = (struct amd_ir_data *)data;