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x86/sev-es: Handle NMI State

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When running under SEV-ES, the kernel has to tell the hypervisor when to
open the NMI window again after an NMI was injected. This is done with
an NMI-complete message to the hypervisor.

Add code to the kernel's NMI handler to send this message right at the
beginning of do_nmi(). This always allows nesting NMIs.

 [ bp: Mark __sev_es_nmi_complete() noinstr:
   vmlinux.o: warning: objtool: exc_nmi()+0x17: call to __sev_es_nmi_complete()
	leaves .noinstr.text section
   While at it, use __pa_nodebug() for the same reason due to
   CONFIG_DEBUG_VIRTUAL=y:
   vmlinux.o: warning: objtool: __sev_es_nmi_complete()+0xd9: call to __phys_addr()
   	leaves .noinstr.text section ]

Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20200907131613.12703-71-joro@8bytes.org
This commit is contained in:
Joerg Roedel
2020-09-07 15:16:11 +02:00
committed by Borislav Petkov
parent 094794f597
commit 4ca68e023b
4 changed files with 32 additions and 0 deletions
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6
arch/x86/kernel/nmi.c
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@@ -478,6 +478,12 @@ DEFINE_IDTENTRY_RAW(exc_nmi)
{
bool irq_state;
/*
* Re-enable NMIs right here when running as an SEV-ES guest. This might
* cause nested NMIs, but those can be handled safely.
*/
sev_es_nmi_complete();
if (IS_ENABLED(CONFIG_SMP) && arch_cpu_is_offline(smp_processor_id()))
return;