Messages in this thread | ![/](/images/icornerl.gif) | | Date | Wed, 20 Mar 2024 10:20:50 +1300 | Subject | Re: [PATCH v2 2/5] x86/kexec: do unconditional WBINVD in relocate_kernel() | From | "Huang, Kai" <> |
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On 20/03/2024 3:38 am, Tom Lendacky wrote: > On 3/19/24 06:13, Kirill A. Shutemov wrote: >> On Tue, Mar 19, 2024 at 01:48:45AM +0000, Kai Huang wrote: >>> Both SME and TDX can leave caches in incoherent state due to memory >>> encryption. During kexec, the caches must be flushed before jumping to >>> the second kernel to avoid silent memory corruption to the second >>> kernel. >>> >>> During kexec, the WBINVD in stop_this_cpu() flushes caches for all >>> remote cpus when they are being stopped. For SME, the WBINVD in >>> relocate_kernel() flushes the cache for the last running cpu (which is >>> executing the kexec). >>> >>> Similarly, for TDX after stopping all remote cpus with cache flushed, to >>> support kexec, the kernel needs to flush cache for the last running cpu. >>> >>> Make the WBINVD in the relocate_kernel() unconditional to cover both SME >>> and TDX. >> >> Nope. It breaks TDX guest. WBINVD triggers #VE for TDX guests. > > Ditto for SEV-ES/SEV-SNP, a #VC is generated and crashes the guest. >
Oh I forgot these.
Hi Kirill,
Then I think patch 1 will also break TDX guest after your series to enable multiple cpus for the second kernel after kexec()?
Hi Tom,
I am not aware of kexec() support status for SEV-ES/SEV-SNP guests. Does patch 1 break them?
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