Messages in this thread Patch in this message | | | From | Tom Lendacky <> | Subject | [PATCH] x86/sev-es: Invalidate the GHCB after completing VMGEXIT | Date | Fri, 14 May 2021 14:12:33 -0500 |
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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 a value of 0 is always present outside VMGEXIT processing in the kernel.
Since vc_ghcb_invalidate() is part of sev-shared.c, move sev_es_put_ghcb() down to after where sev-shared.c is included.
Fixes: 0786138c78e79 ("x86/sev-es: Add a Runtime #VC Exception Handler") Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com> --- arch/x86/kernel/sev-shared.c | 1 + arch/x86/kernel/sev.c | 37 ++++++++++++++++++------------------ 2 files changed, 20 insertions(+), 18 deletions(-)
diff --git a/arch/x86/kernel/sev-shared.c b/arch/x86/kernel/sev-shared.c index 6ec8b3bfd76e..9f90f460a28c 100644 --- a/arch/x86/kernel/sev-shared.c +++ b/arch/x86/kernel/sev-shared.c @@ -63,6 +63,7 @@ static bool sev_es_negotiate_protocol(void) 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)); } diff --git a/arch/x86/kernel/sev.c b/arch/x86/kernel/sev.c index 9578c82832aa..5ccb0218c885 100644 --- a/arch/x86/kernel/sev.c +++ b/arch/x86/kernel/sev.c @@ -221,24 +221,6 @@ static __always_inline struct ghcb *sev_es_get_ghcb(struct ghcb_state *state) return ghcb; } -static __always_inline void sev_es_put_ghcb(struct ghcb_state *state) -{ - struct sev_es_runtime_data *data; - struct ghcb *ghcb; - - data = this_cpu_read(runtime_data); - ghcb = &data->ghcb_page; - - if (state->ghcb) { - /* Restore GHCB from Backup */ - *ghcb = *state->ghcb; - data->backup_ghcb_active = false; - state->ghcb = NULL; - } else { - data->ghcb_active = false; - } -} - /* Needed in vc_early_forward_exception */ void do_early_exception(struct pt_regs *regs, int trapnr); @@ -461,6 +443,25 @@ static enum es_result vc_slow_virt_to_phys(struct ghcb *ghcb, struct es_em_ctxt /* Include code shared with pre-decompression boot stage */ #include "sev-shared.c" +static __always_inline void sev_es_put_ghcb(struct ghcb_state *state) +{ + struct sev_es_runtime_data *data; + struct ghcb *ghcb; + + data = this_cpu_read(runtime_data); + ghcb = &data->ghcb_page; + + if (state->ghcb) { + /* Restore GHCB from Backup */ + *ghcb = *state->ghcb; + data->backup_ghcb_active = false; + state->ghcb = NULL; + } else { + vc_ghcb_invalidate(ghcb); + data->ghcb_active = false; + } +} + void noinstr __sev_es_nmi_complete(void) { struct ghcb_state state; -- 2.31.0
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