Kernel KVM virtualization development
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From: "Chang S. Bae" <chang.seok.bae@intel.com>
To: pbonzini@redhat.com, seanjc@google.com
Cc: kvm@vger.kernel.org, x86@kernel.org,
	linux-kernel@vger.kernel.org, chang.seok.bae@intel.com
Subject: [PATCH v5 14/20] KVM: x86: Move KVM_SUPPORTED_{XCR0,XSS} into kvm_x86_vendor_init()
Date: Mon, 20 Jul 2026 17:19:43 +0000	[thread overview]
Message-ID: <20260720171949.498680-15-chang.seok.bae@intel.com> (raw)
In-Reply-To: <20260720171949.498680-1-chang.seok.bae@intel.com>

From: Sean Christopherson <seanjc@google.com>

Move KVM_SUPPORTED_{XCR0,XSS} into kvm_x86_vendor_init() as "const u64"
values so that KVM's initialization code can further manipulate the set
of supported XCR0/XSS features without ugly #ifdeffery and without
risking other code treating KVM_SUPPORTED_{XCR0,XSS} as 100%
authoritative.

No functional change intended.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Chang S. Bae <chang.seok.bae@intel.com>
Link: https://lore.kernel.org/ahmtyMNsj2BCoEEo@google.com
---
V4 -> V5: New patch (Sean)
---
 arch/x86/kvm/cpuid.c |  2 +-
 arch/x86/kvm/x86.c   | 25 +++++++++++++------------
 2 files changed, 14 insertions(+), 13 deletions(-)

diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index 122e46db9a15..1fc7a0f9a13a 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -264,7 +264,7 @@ static u32 kvm_apply_cpuid_pv_features_quirk(struct kvm_vcpu *vcpu)
 
 /*
  * Calculate guest's supported XCR0 taking into account guest CPUID data and
- * KVM's supported XCR0 (comprised of host's XCR0 and KVM_SUPPORTED_XCR0).
+ * KVM's supported XCR0 (the host's actual XCR0 masked by what KVM supports).
  */
 static u64 cpuid_get_supported_xcr0(struct kvm_vcpu *vcpu)
 {
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 5578df10179a..84b2dcfcb007 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -191,19 +191,7 @@ module_param(pi_inject_timer, bint, 0644);
 static bool __read_mostly mitigate_smt_rsb;
 module_param(mitigate_smt_rsb, bool, 0444);
 
-#define KVM_SUPPORTED_XCR0     (XFEATURE_MASK_FP | XFEATURE_MASK_SSE \
-				| XFEATURE_MASK_YMM | XFEATURE_MASK_BNDREGS \
-				| XFEATURE_MASK_BNDCSR | XFEATURE_MASK_AVX512 \
-				| XFEATURE_MASK_PKRU | XFEATURE_MASK_XTILE)
-
 #define XFEATURE_MASK_CET_ALL	(XFEATURE_MASK_CET_USER | XFEATURE_MASK_CET_KERNEL)
-/*
- * Note, KVM supports exposing PT to the guest, but does not support context
- * switching PT via XSTATE (KVM's PT virtualization relies on perf; swapping
- * PT via guest XSTATE would clobber perf state), i.e. KVM doesn't support
- * IA32_XSS[bit 8] (guests can/must use RDMSR/WRMSR to save/restore PT MSRs).
- */
-#define KVM_SUPPORTED_XSS	(XFEATURE_MASK_CET_ALL)
 
 bool __read_mostly allow_smaller_maxphyaddr = 0;
 EXPORT_SYMBOL_FOR_KVM_INTERNAL(allow_smaller_maxphyaddr);
@@ -7009,6 +6997,19 @@ static void kvm_x86_check_cpu_compat(void *ret)
 
 int kvm_x86_vendor_init(struct kvm_x86_init_ops *ops)
 {
+	const u64 KVM_SUPPORTED_XCR0 = XFEATURE_MASK_FP | XFEATURE_MASK_SSE |
+				       XFEATURE_MASK_YMM | XFEATURE_MASK_BNDREGS |
+				       XFEATURE_MASK_BNDCSR | XFEATURE_MASK_AVX512 |
+				       XFEATURE_MASK_PKRU | XFEATURE_MASK_XTILE;
+	/*
+	 * Note, KVM supports exposing PT to the guest, but does not support
+	 * context switching PT via XSTATE (KVM's PT virtualization relies on
+	 * perf; swapping PT via guest XSTATE would clobber perf state), i.e.
+	 * KVM doesn't support IA32_XSS[bit 8] (guests can/must use RDMSR/WRMSR
+	 * to save/restore PT MSRs).
+	 */
+	const u64 KVM_SUPPORTED_XSS = XFEATURE_MASK_CET_ALL;
+
 	u64 host_pat;
 	int r, cpu;
 
-- 
2.53.0


  parent reply	other threads:[~2026-07-20 17:46 UTC|newest]

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-07-20 17:19 [PATCH v5 00/20] KVM: x86: Enable APX for guests Chang S. Bae
2026-07-20 17:19 ` [PATCH v5 01/20] KVM: x86: Extend VCPU registers for EGPRs Chang S. Bae
2026-07-20 17:19 ` [PATCH v5 02/20] KVM: VMX: Save guest EGPRs in VCPU cache Chang S. Bae
2026-07-20 18:20   ` sashiko-bot
2026-07-20 17:19 ` [PATCH v5 03/20] KVM: x86: Support APX state for XSAVE ABI Chang S. Bae
2026-07-20 18:22   ` sashiko-bot
2026-07-20 17:19 ` [PATCH v5 04/20] KVM: VMX: Refactor VMX instruction information access Chang S. Bae
2026-07-20 17:19 ` [PATCH v5 05/20] KVM: VMX: Refactor instruction information decoding Chang S. Bae
2026-07-20 17:19 ` [PATCH v5 06/20] KVM: VMX: Remove unused control-register access defines Chang S. Bae
2026-07-20 17:19 ` [PATCH v5 07/20] KVM: VMX: Refactor register index retrieval from exit qualification Chang S. Bae
2026-07-20 17:19 ` [PATCH v5 08/20] KVM: VMX: Support instruction information extension Chang S. Bae
2026-07-20 18:12   ` sashiko-bot
2026-07-20 17:19 ` [PATCH v5 09/20] KVM: nVMX: Propagate extended instruction information Chang S. Bae
2026-07-20 18:10   ` sashiko-bot
2026-07-20 17:19 ` [PATCH v5 10/20] KVM: x86: Support EGPR accessing and tracking for emulator Chang S. Bae
2026-07-20 17:19 ` [PATCH v5 11/20] KVM: x86: Handle EGPR index and REX2-incompatible opcodes Chang S. Bae
2026-07-20 18:18   ` sashiko-bot
2026-07-20 17:19 ` [PATCH v5 12/20] KVM: x86: Support REX2-prefixed opcode decode Chang S. Bae
2026-07-20 17:19 ` [PATCH v5 13/20] KVM: x86: Reject EVEX-prefixed instructions Chang S. Bae
2026-07-20 18:11   ` sashiko-bot
2026-07-20 17:19 ` Chang S. Bae [this message]
2026-07-20 17:19 ` [PATCH v5 15/20] KVM: x86: Guard valid XCR0.APX settings Chang S. Bae
2026-07-20 17:19 ` [PATCH v5 16/20] KVM: x86: Add APX in supported XCR0 Chang S. Bae
2026-07-20 18:25   ` sashiko-bot
2026-07-20 17:19 ` [PATCH v5 17/20] KVM: x86: Expose APX foundation feature to userspace Chang S. Bae
2026-07-20 18:12   ` sashiko-bot
2026-07-20 17:19 ` [PATCH v5 18/20] KVM: x86: Expose APX sub-features " Chang S. Bae
2026-07-20 18:10   ` sashiko-bot
2026-07-20 17:19 ` [PATCH v5 19/20] KVM: x86: selftests: Add APX state and ABI test Chang S. Bae
2026-07-20 18:17   ` sashiko-bot
2026-07-20 17:19 ` [PATCH v5 20/20] KVM: x86: selftests: Add APX state handling and XCR0 sanity checks Chang S. Bae
2026-07-21  7:09 ` [PATCH v5 00/20] KVM: x86: Enable APX for guests Paolo Bonzini

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