From: Dave Hansen <dave.hansen@intel.com>
To: "Edgecombe, Rick P" <rick.p.edgecombe@intel.com>,
"linux-coco@lists.linux.dev" <linux-coco@lists.linux.dev>,
"clopez@suse.de" <clopez@suse.de>,
"kas@kernel.org" <kas@kernel.org>,
"x86@kernel.org" <x86@kernel.org>
Cc: "ak@linux.intel.com" <ak@linux.intel.com>,
"bp@alien8.de" <bp@alien8.de>,
"dave.hansen@linux.intel.com" <dave.hansen@linux.intel.com>,
"hpa@zytor.com" <hpa@zytor.com>,
"mingo@redhat.com" <mingo@redhat.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"Luck, Tony" <tony.luck@intel.com>,
"tglx@kernel.org" <tglx@kernel.org>,
"stable@vger.kernel.org" <stable@vger.kernel.org>,
"kvm@vger.kernel.org" <kvm@vger.kernel.org>
Subject: Re: [PATCH] x86/tdx: Fix zero-extension for CPUID emulation
Date: Tue, 12 May 2026 15:37:05 -0700 [thread overview]
Message-ID: <d76284f1-79e2-4e7b-94e7-252ff3ee9e5e@intel.com> (raw)
In-Reply-To: <43a913a1b4721c752443416a685631478bee2f10.camel@intel.com>
On 5/12/26 15:24, Edgecombe, Rick P wrote:
> On the other hand, the #VE handler is supposed to do the emulation of the
> instruction, with the help of the TDVMCALL, so maybe the correctness should be
> in the guest... Hmm...
Maybe we should just change the GHCI spec.
What if we said:
| Operand | ... |
| R12 (lower 32 bits) | EAX |
| R13 (lower 32 bits) | EBX |
| R14 (lower 32 bits) | ECX |
| R15 (lower 32 bits) | EDX |
Then said the upper 32 bits are undefined. Then the kernel *must* mask
them to be correct. Then we don't have to do any checking at all and
there's no ambiguity about what the VMM is allowed to do or what chaos
it might cause.
next prev parent reply other threads:[~2026-05-12 22:37 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-05-12 21:37 [PATCH] x86/tdx: Fix zero-extension for CPUID emulation Carlos López
2026-05-12 21:48 ` Edgecombe, Rick P
2026-05-12 22:14 ` Dave Hansen
2026-05-12 22:24 ` Edgecombe, Rick P
2026-05-12 22:37 ` Dave Hansen [this message]
2026-05-12 22:43 ` Edgecombe, Rick P
2026-05-12 22:33 ` Carlos López
2026-05-12 22:15 ` Carlos López
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