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(Kirill, Tom) > - Point out "WBINVD is not necessary for TDX and SEV-ES/SEV-SNP guests" > in the comment. (Tom) > > v2 -> v3: > - Change to only do WBINVD for bare metal > > --- > arch/x86/kernel/process.c | 19 +++++++++---------- > 1 file changed, 9 insertions(+), 10 deletions(-) > > diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c > index b8441147eb5e..d3c904bfe874 100644 > --- a/arch/x86/kernel/process.c > +++ b/arch/x86/kernel/process.c > @@ -813,18 +813,17 @@ void __noreturn stop_this_cpu(void *dummy) > mcheck_cpu_clear(c); > > /* > - * Use wbinvd on processors that support SME. This provides support > - * for performing a successful kexec when going from SME inactive > - * to SME active (or vice-versa). The cache must be cleared so that > - * if there are entries with the same physical address, both with and > - * without the encryption bit, they don't race each other when flushed > - * and potentially end up with the wrong entry being committed to > - * memory. > + * The kernel could leave caches in incoherent state on SME/TDX > + * capable platforms. Flush cache to avoid silent memory > + * corruption for these platforms. > * > - * Test the CPUID bit directly because the machine might've cleared > - * X86_FEATURE_SME due to cmdline options. > + * stop_this_cpu() isn't a fast path, just do WBINVD for bare-metal > + * to cover both SME and TDX. It isn't necessary to perform WBINVD > + * in a guest and performing one could result in an exception (#VE > + * or #VC) for a TDX or SEV-ES/SEV-SNP guest that the guest may > + * not be able to handle (e.g., TDX guest panics if it sees #VE). > */ > - if (c->extended_cpuid_level >= 0x8000001f && (cpuid_eax(0x8000001f) & BIT(0))) > + if (!boot_cpu_has(X86_FEATURE_HYPERVISOR)) > native_wbinvd(); > > /*