On Fri, Sep 25, 2020 at 11:45:05AM +0000, Suravee Suthikulpanit wrote:
When using 128-bit interrupt-remapping table entry (IRTE) (a.k.a GA mode), current driver disables interrupt remapping when it updates the IRTE so that the upper and lower 64-bit values can be updated safely.
However, this creates a small window, where the interrupt could arrive and result in IO_PAGE_FAULT (for interrupt) as shown below.
IOMMU Driver Device IRQ ============ =========== irte.RemapEn=0 ... change IRTE IRQ from device ==> IO_PAGE_FAULT !! ... irte.RemapEn=1
This scenario has been observed when changing irq affinity on a system running I/O-intensive workload, in which the destination APIC ID in the IRTE is updated.
Instead, use cmpxchg_double() to update the 128-bit IRTE at once without disabling the interrupt remapping. However, this means several features, which require GA (128-bit IRTE) support will also be affected if cmpxchg16b is not supported (which is unprecedented for AMD processors w/ IOMMU).
Cc: stable@vger.kernel.org Fixes: 880ac60e2538 ("iommu/amd: Introduce interrupt remapping ops structure") Reported-by: Sean Osborne sean.m.osborne@oracle.com Signed-off-by: Suravee Suthikulpanit suravee.suthikulpanit@amd.com Tested-by: Erik Rockstrom erik.rockstrom@oracle.com Reviewed-by: Joao Martins joao.m.martins@oracle.com Link: https://lore.kernel.org/r/20200903093822.52012-3-suravee.suthikulpanit@amd.c... Signed-off-by: Joerg Roedel jroedel@suse.de
Note: This patch is the back-port on top of the stable branch linux-5.4.y for the upstream commit e52d58d54a32 ("iommu/amd: Use cmpxchg_double() when updating 128-bit IRTE") since the original patch does not apply cleanly.
Now queued up, thanks.
greg k-h