archives/linux
1
0
Fork 0
mirror of https://github.com/torvalds/linux.git synced 2026-03-08 08:44:46 +01:00
Code Issues Projects Releases Packages Wiki Activity Actions

x86/boot: Drop redundant RMPADJUST in SEV SVSM presence check

Browse source 
snp_vmpl will be assigned a non-zero value when executing at a VMPL other than
0, and this is inferred from a call to RMPADJUST, which only works when
running at VMPL0.

This means that testing snp_vmpl is sufficient, and there is no need to
perform the same check again.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/20250828102202.1849035-34-ardb+git@google.com
This commit is contained in:
Ard Biesheuvel 2025-08-28 12:22:13 +02:00 • committed by Borislav Petkov (AMD)
parent c54604fb7f
commit 68a501d7fd
1 changed files with 3 additions and 17 deletions
Download patch file Download diff file Expand all files Collapse all files

20
arch/x86/boot/compressed/sev.c
View file

@ -406,30 +406,16 @@ void sev_enable(struct boot_params *bp)
*/
if (sev_status & MSR_AMD64_SEV_SNP_ENABLED) {
u64 hv_features;
int ret;
hv_features = get_hv_features();
if (!(hv_features & GHCB_HV_FT_SNP))
sev_es_terminate(SEV_TERM_SET_GEN, GHCB_SNP_UNSUPPORTED);
/*
* Enforce running at VMPL0 or with an SVSM.
*
* Use RMPADJUST (see the rmpadjust() function for a description of
* what the instruction does) to update the VMPL1 permissions of a
* page. If the guest is running at VMPL0, this will succeed. If the
* guest is running at any other VMPL, this will fail. Linux SNP guests
* only ever run at a single VMPL level so permission mask changes of a
* lesser-privileged VMPL are a don't-care.
* Running at VMPL0 is required unless an SVSM is present and
* the hypervisor supports the required SVSM GHCB events.
*/
ret = rmpadjust((unsigned long)&boot_ghcb_page, RMP_PG_SIZE_4K, 1);
/*
* Running at VMPL0 is not required if an SVSM is present and the hypervisor
* supports the required SVSM GHCB events.
*/
if (ret &&
!(snp_vmpl && (hv_features & GHCB_HV_FT_SNP_MULTI_VMPL)))
if (snp_vmpl && !(hv_features & GHCB_HV_FT_SNP_MULTI_VMPL))
sev_es_terminate(SEV_TERM_SET_LINUX, GHCB_TERM_NOT_VMPL0);
}