linux-kernel - [PATCH v4 0/2] Support for SEV-ES guest shadow stack

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Message-ID: <20251014194347.2374-1-john.allen@amd.com>
Date: Tue, 14 Oct 2025 19:43:45 +0000
From: John Allen <john.allen@....com>
To: <kvm@...r.kernel.org>, <linux-kernel@...r.kernel.org>, <x86@...nel.org>,
	<seanjc@...gle.com>, <pbonzini@...hat.com>, <dave.hansen@...el.com>
CC: <rick.p.edgecombe@...el.com>, <mlevitsk@...hat.com>,
	<weijiang.yang@...el.com>, <chao.gao@...el.com>, <bp@...en8.de>,
	<dave.hansen@...ux.intel.com>, <hpa@...or.com>, <mingo@...hat.com>,
	<tglx@...utronix.de>, <thomas.lendacky@....com>, John Allen
	<john.allen@....com>
Subject: [PATCH v4 0/2] Support for SEV-ES guest shadow stack

For shadow stack support in SVM when using SEV-ES, the guest kernel
needs to save XSS to the GHCB in order for the hypervisor to determine
the XSAVES save area size.
---
v4:
  - Use CPUID_LEAF_XSTATE instead of open coding 0xd.
v3:
  - Only CPUID.0xD.1 consumes XSS. Limit including XSS in GHCB for this
    case.
v2:
  - Update changelog for patch 2/2

John Allen (2):
  x86/boot: Move boot_*msr helpers to asm/shared/msr.h
  x86/sev-es: Include XSS value in GHCB CPUID request

 arch/x86/boot/compressed/sev.c    |  7 ++++---
 arch/x86/boot/compressed/sev.h    |  6 +++---
 arch/x86/boot/cpucheck.c          | 16 ++++++++--------
 arch/x86/boot/msr.h               | 26 --------------------------
 arch/x86/coco/sev/vc-shared.c     | 13 +++++++++++++
 arch/x86/include/asm/shared/msr.h | 15 +++++++++++++++
 arch/x86/include/asm/svm.h        |  1 +
 7 files changed, 44 insertions(+), 40 deletions(-)
 delete mode 100644 arch/x86/boot/msr.h

-- 
2.47.3