From: John Allen <john.allen@amd.com>
To: Dave Hansen <dave.hansen@intel.com>
Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
x86@kernel.org, seanjc@google.com, pbonzini@redhat.com,
rick.p.edgecombe@intel.com, mlevitsk@redhat.com,
weijiang.yang@intel.com, chao.gao@intel.com, bp@alien8.de,
dave.hansen@linux.intel.com, hpa@zytor.com, mingo@redhat.com,
tglx@linutronix.de, thomas.lendacky@amd.com
Subject: Re: [PATCH v3 2/2] x86/sev-es: Include XSS value in GHCB CPUID request
Date: Fri, 26 Sep 2025 14:22:59 -0500 [thread overview]
Message-ID: <aNboE3FqdjgqlEuy@AUSJOHALLEN.amd.com> (raw)
In-Reply-To: <e0b0180f-17aa-444a-8ede-39709501e82b@intel.com>
On Wed, Sep 24, 2025 at 04:02:11PM -0700, Dave Hansen wrote:
> On 9/24/25 13:08, John Allen wrote:
> > + if (has_cpuflag(X86_FEATURE_SHSTK) && regs->ax == 0xd && regs->cx == 1) {
> > + struct msr m;
> > +
> > + raw_rdmsr(MSR_IA32_XSS, &m);
> > + ghcb_set_xss(ghcb, m.q);
> > + }
>
> Is there a reason this is open-coding CPUID_LEAF_XSTATE?
That's a good question. This patch was adapted from an old SNP patch
from years ago so if I had to guess, maybe there was some issue bringing
in the old pre-split cpuid header into the early boot/shared
environment. It looks like including asm/cpuid/types.h and using
CPUID_LEAF_XSTATE works here and now so I'll include it in the next
version.
Thanks,
John
next prev parent reply other threads:[~2025-09-26 19:23 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-09-24 20:08 [PATCH v3 0/2] Support for SEV-ES guest shadow stack John Allen
2025-09-24 20:08 ` [PATCH v3 1/2] x86/boot: Move boot_*msr helpers to asm/shared/msr.h John Allen
2025-09-24 20:08 ` [PATCH v3 2/2] x86/sev-es: Include XSS value in GHCB CPUID request John Allen
2025-09-24 23:02 ` Dave Hansen
2025-09-26 19:22 ` John Allen [this message]
2025-10-31 12:21 ` [PATCH] x86/coco/sev: Convert has_cpuflag() to use cpu_feature_enabled() Borislav Petkov
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