From: Tom Lendacky <thomas.lendacky@amd.com>
To: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
Kai Huang <kai.huang@intel.com>
Cc: linux-kernel@vger.kernel.org, x86@kernel.org,
dave.hansen@intel.com, bp@alien8.de, tglx@linutronix.de,
mingo@redhat.com, hpa@zytor.com, luto@kernel.org,
peterz@infradead.org, rick.p.edgecombe@intel.com,
ashish.kalra@amd.com, chao.gao@intel.com, bhe@redhat.com,
nik.borisov@suse.com, pbonzini@redhat.com, seanjc@google.com
Subject: Re: [PATCH v2 2/5] x86/kexec: do unconditional WBINVD in relocate_kernel()
Date: Tue, 19 Mar 2024 09:38:30 -0500 [thread overview]
Message-ID: <38fca2fa-11b2-4eb7-9e59-dc5d524d172e@amd.com> (raw)
In-Reply-To: <tvembdwwh4immxytlfzlhpvd42dlfsz7sddb7msk23kdduhu3t@ogpc66hklorv>
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.
Thanks,
Tom
>
next prev parent reply other threads:[~2024-03-19 14:38 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-03-19 1:48 [PATCH v2 0/5] TDX host: kexec() support Kai Huang
2024-03-19 1:48 ` [PATCH v2 1/5] x86/kexec: do unconditional WBINVD in stop_this_cpu() Kai Huang
2024-03-19 1:48 ` [PATCH v2 2/5] x86/kexec: do unconditional WBINVD in relocate_kernel() Kai Huang
2024-03-19 11:13 ` Kirill A. Shutemov
2024-03-19 14:38 ` Tom Lendacky [this message]
2024-03-19 21:20 ` Huang, Kai
2024-03-20 0:19 ` Kirill A. Shutemov
2024-03-20 0:45 ` Huang, Kai
2024-03-20 12:51 ` Kirill A. Shutemov
2024-03-20 13:49 ` Tom Lendacky
2024-03-20 20:48 ` Huang, Kai
2024-03-20 21:06 ` Tom Lendacky
2024-03-20 21:58 ` Huang, Kai
2024-03-20 23:10 ` Kirill A. Shutemov
2024-03-21 21:02 ` Tom Lendacky
2024-03-22 10:40 ` Kirill A. Shutemov
2024-03-22 14:50 ` Tom Lendacky
2024-03-25 13:04 ` Huang, Kai
2024-03-28 16:10 ` kirill.shutemov
2024-04-01 9:13 ` Huang, Kai
2024-03-19 15:41 ` Borislav Petkov
2024-03-19 21:08 ` Huang, Kai
2024-03-19 1:48 ` [PATCH v2 3/5] x86/kexec: Reset TDX private memory on platforms with TDX erratum Kai Huang
2024-03-19 1:48 ` [PATCH v2 4/5] x86/virt/tdx: Remove the !KEXEC_CORE dependency Kai Huang
2024-03-19 1:48 ` [PATCH v2 5/5] x86/virt/tdx: Add TDX memory reset notifier to reset other private pages Kai Huang
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