Messages in this thread | ![/](/images/icornerl.gif) | | Date | Wed, 10 Apr 2024 17:12:49 +0300 | From | "Kirill A. Shutemov" <> | Subject | Re: [PATCH v3 1/5] x86/kexec: do unconditional WBINVD for bare-metal in stop_this_cpu() |
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On Mon, Apr 08, 2024 at 12:44:54AM +1200, Kai Huang wrote: > TL;DR:
The commit message is waaay too verbose for no good reason. You don't really need to repeat all the history around this code.
> --- > arch/x86/kernel/process.c | 18 ++++++++---------- > 1 file changed, 8 insertions(+), 10 deletions(-) > > diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c > index b8441147eb5e..5ba8a9c1e47a 100644 > --- a/arch/x86/kernel/process.c > +++ b/arch/x86/kernel/process.c > @@ -813,18 +813,16 @@ 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() is not a fast path, just do unconditional > + * WBINVD for simplicity. But only do WBINVD for bare-metal > + * as TDX guests and SEV-ES/SEV-SNP guests will get unexpected > + * (and unnecessary) #VE and may unable to handle.
s/#VE/exception/
On SEV it is #VC, not #VE.
-- Kiryl Shutsemau / Kirill A. Shutemov
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