x86/sev: Make vTPM SVSM calls preemption-safe

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Two functions in the SVSM vTPM guest implementation do not disable
preemption when fetching the SVSM Calling Area Address (CAA).

The SVSM CAA is a per-CPU structure. When a thread is preempted and migrated
to a different CPU after fetching the per-CPU CAA, the SVSM call will execute
on the new CPU with the original CPU's CAA. Which is wrong.

Move the CAA fetching operation inside svsm_perform_call_protocol() which
disables interrupts around the SVSM call and thus runs preemption-safe.

Fixes: 770de678bc ("x86/sev: Add SVSM vTPM probe/send_command functions")
Signed-off-by: Melody Wang <huibo.wang@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/a5bc0d4a2c462a0089109e145c21626b244b2ff0.1789345277.git.huibo.wang@amd.com

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Melody Wang 2026-09-14 00:57:17 +00:00 • committed by Borislav Petkov (AMD)

parent 93f51579e7

commit 6c43c72748

1 changed files with 8 additions and 2 deletions

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arch/x86/coco/sev/svsm.c

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