x86/bugs: Add SRSO_USER_KERNEL_NO support
commit 877818802c3e970f67ccb53012facc78bef5f97a upstream.
If the machine has:
CPUID Fn8000_0021_EAX[30] (SRSO_USER_KERNEL_NO) -- If this bit is 1,
it indicates the CPU is not subject to the SRSO vulnerability across
user/kernel boundaries.
have it fall back to IBPB on VMEXIT only, in the case it is going to run
VMs:
Speculative Return Stack Overflow: Mitigation: IBPB on VMEXIT only
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Nikolay Borisov <nik.borisov@suse.com>
Link: https://lore.kernel.org/r/20241202120416.6054-2-bp@kernel.org
[ Harshit: Conflicts resolved as this commit: 7c62c442b6eb ("x86/vmscape:
Enumerate VMSCAPE bug") has been applied already to 6.12.y ]
Signed-off-by: Harshit Mogalapalli <harshit.m.mogalapalli@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2 files changed
