From: Tom Lendacky thomas.lendacky@amd.com
commit a50c5bebc99c525e7fbc059988c6a5ab8680cb76 upstream.
Since the VMGEXIT instruction can be issued from userspace, invalidate the GHCB after performing VMGEXIT processing in the kernel.
Invalidation is only required after userspace is available, so call vc_ghcb_invalidate() from sev_es_put_ghcb(). Update vc_ghcb_invalidate() to additionally clear the GHCB exit code so that it is always presented as 0 when VMGEXIT has been issued by anything else besides the kernel.
Fixes: 0786138c78e79 ("x86/sev-es: Add a Runtime #VC Exception Handler") Signed-off-by: Tom Lendacky thomas.lendacky@amd.com Signed-off-by: Borislav Petkov bp@suse.de Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/5a8130462e4f0057ee1184509cd056eedd78742b.162127335... Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/x86/kernel/sev-es-shared.c | 1 + arch/x86/kernel/sev-es.c | 5 +++++ 2 files changed, 6 insertions(+)
--- a/arch/x86/kernel/sev-es-shared.c +++ b/arch/x86/kernel/sev-es-shared.c @@ -63,6 +63,7 @@ static bool sev_es_negotiate_protocol(vo
static __always_inline void vc_ghcb_invalidate(struct ghcb *ghcb) { + ghcb->save.sw_exit_code = 0; memset(ghcb->save.valid_bitmap, 0, sizeof(ghcb->save.valid_bitmap)); }
--- a/arch/x86/kernel/sev-es.c +++ b/arch/x86/kernel/sev-es.c @@ -430,6 +430,11 @@ static __always_inline void sev_es_put_g data->backup_ghcb_active = false; state->ghcb = NULL; } else { + /* + * Invalidate the GHCB so a VMGEXIT instruction issued + * from userspace won't appear to be valid. + */ + vc_ghcb_invalidate(ghcb); data->ghcb_active = false; } }