On Wed, Nov 09, 2022 at 09:37:20AM -0800, Pawan Gupta wrote:
Looks like we need to restore this MSR too,
Why do we? Is that MSR read-only too or what is the reason for that one?
Yes, MSR_AMD64_LS_CFG is used in SSBD mitigations. For everything <= 0x12:
/* AMD Family 0xf - 0x12 */
VULNWL_AMD(0x0f, NO_MELTDOWN | NO_SSB | NO_L1TF | NO_MDS | NO_SWAPGS | NO_ITLB_MULTIHIT | NO_MMIO),
VULNWL_AMD(0x10, NO_MELTDOWN | NO_SSB | NO_L1TF | NO_MDS | NO_SWAPGS | NO_ITLB_MULTIHIT | NO_MMIO),
VULNWL_AMD(0x11, NO_MELTDOWN | NO_SSB | NO_L1TF | NO_MDS | NO_SWAPGS | NO_ITLB_MULTIHIT | NO_MMIO),
VULNWL_AMD(0x12, NO_MELTDOWN | NO_SSB | NO_L1TF | NO_MDS | NO_SWAPGS | NO_ITLB_MULTIHIT | NO_MMIO),
On F14h it says here:
[ 0.278930] Speculative Store Bypass: Vulnerable
simply because it is not present there.