diff options
| author | Joerg Roedel <jroedel@suse.de> | 2020-09-07 15:15:44 +0200 |
|---|---|---|
| committer | Borislav Petkov <bp@suse.de> | 2020-09-09 11:33:19 +0200 |
| commit | 315562c9af3d583502b35c4b223a08d95ce69864 (patch) | |
| tree | a3351da80cc8801eadebe8185d591583f5e49760 /arch/x86/kernel/nmi.c | |
| parent | 02772fb9b68e6a72a5e17f994048df832fe2b15e (diff) | |
x86/sev-es: Adjust #VC IST Stack on entering NMI handler
When an NMI hits in the #VC handler entry code before it has switched to
another stack, any subsequent #VC exception in the NMI code-path will
overwrite the interrupted #VC handler's stack.
Make sure this doesn't happen by explicitly adjusting the #VC IST entry
in the NMI handler for the time it can cause #VC exceptions.
[ bp: Touchups, spelling fixes. ]
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20200907131613.12703-44-joro@8bytes.org
Diffstat (limited to 'arch/x86/kernel/nmi.c')
| -rw-r--r-- | arch/x86/kernel/nmi.c | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/arch/x86/kernel/nmi.c b/arch/x86/kernel/nmi.c index 4fc9954a9560..4c89c4d3cb82 100644 --- a/arch/x86/kernel/nmi.c +++ b/arch/x86/kernel/nmi.c @@ -33,6 +33,7 @@ #include <asm/reboot.h> #include <asm/cache.h> #include <asm/nospec-branch.h> +#include <asm/sev-es.h> #define CREATE_TRACE_POINTS #include <trace/events/nmi.h> @@ -488,6 +489,12 @@ DEFINE_IDTENTRY_RAW(exc_nmi) this_cpu_write(nmi_cr2, read_cr2()); nmi_restart: + /* + * Needs to happen before DR7 is accessed, because the hypervisor can + * intercept DR7 reads/writes, turning those into #VC exceptions. + */ + sev_es_ist_enter(regs); + this_cpu_write(nmi_dr7, local_db_save()); irq_state = idtentry_enter_nmi(regs); @@ -501,6 +508,8 @@ nmi_restart: local_db_restore(this_cpu_read(nmi_dr7)); + sev_es_ist_exit(); + if (unlikely(this_cpu_read(nmi_cr2) != read_cr2())) write_cr2(this_cpu_read(nmi_cr2)); if (this_cpu_dec_return(nmi_state)) |