linux-kernel - [PATCH v5 14/44] KVM: VMX: Setup canonical VMCS config prior to kvm_x86_vendor

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Message-ID: <20250806195706.1650976-15-seanjc@google.com>
Date: Wed,  6 Aug 2025 12:56:36 -0700
From: Sean Christopherson <seanjc@...gle.com>
To: Marc Zyngier <maz@...nel.org>, Oliver Upton <oliver.upton@...ux.dev>, 
	Tianrui Zhao <zhaotianrui@...ngson.cn>, Bibo Mao <maobibo@...ngson.cn>, 
	Huacai Chen <chenhuacai@...nel.org>, Anup Patel <anup@...infault.org>, 
	Paul Walmsley <paul.walmsley@...ive.com>, Palmer Dabbelt <palmer@...belt.com>, 
	Albert Ou <aou@...s.berkeley.edu>, Xin Li <xin@...or.com>, "H. Peter Anvin" <hpa@...or.com>, 
	Andy Lutomirski <luto@...nel.org>, Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...hat.com>, 
	Arnaldo Carvalho de Melo <acme@...nel.org>, Namhyung Kim <namhyung@...nel.org>, 
	Sean Christopherson <seanjc@...gle.com>, Paolo Bonzini <pbonzini@...hat.com>
Cc: linux-arm-kernel@...ts.infradead.org, kvmarm@...ts.linux.dev, 
	kvm@...r.kernel.org, loongarch@...ts.linux.dev, kvm-riscv@...ts.infradead.org, 
	linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org, 
	linux-perf-users@...r.kernel.org, Kan Liang <kan.liang@...ux.intel.com>, 
	Yongwei Ma <yongwei.ma@...el.com>, Mingwei Zhang <mizhang@...gle.com>, 
	Xiong Zhang <xiong.y.zhang@...ux.intel.com>, Sandipan Das <sandipan.das@....com>, 
	Dapeng Mi <dapeng1.mi@...ux.intel.com>
Subject: [PATCH v5 14/44] KVM: VMX: Setup canonical VMCS config prior to kvm_x86_vendor_init()

Setup the golden VMCS config during vmx_init(), before the call to
kvm_x86_vendor_init(), instead of waiting until the callback to do
hardware setup.  setup_vmcs_config() only touches VMX state, i.e. doesn't
poke anything in kvm.ko, and has no runtime dependencies beyond
hv_init_evmcs().

Setting the VMCS config early on will allow referencing VMCS and VMX
capabilities at any point during setup, e.g. to check for PERF_GLOBAL_CTRL
save/load support during mediated PMU initialization.

Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 arch/x86/kvm/vmx/vmx.c | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 95765db52992..ed10013dac95 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -8335,8 +8335,6 @@ __init int vmx_hardware_setup(void)
 
 	vmx_setup_user_return_msrs();
 
-	if (setup_vmcs_config(&vmcs_config, &vmx_capability) < 0)
-		return -EIO;
 
 	if (boot_cpu_has(X86_FEATURE_NX))
 		kvm_enable_efer_bits(EFER_NX);
@@ -8560,11 +8558,18 @@ int __init vmx_init(void)
 		return -EOPNOTSUPP;
 
 	/*
-	 * Note, hv_init_evmcs() touches only VMX knobs, i.e. there's nothing
-	 * to unwind if a later step fails.
+	 * Note, VMCS and eVMCS configuration only touch VMX knobs/variables,
+	 * i.e. there's nothing to unwind if a later step fails.
 	 */
 	hv_init_evmcs();
 
+	/*
+	 * Parse the VMCS config and VMX capabilities before anything else, so
+	 * that the information is available to all setup flows.
+	 */
+	if (setup_vmcs_config(&vmcs_config, &vmx_capability) < 0)
+		return -EIO;
+
 	r = kvm_x86_vendor_init(&vt_init_ops);
 	if (r)
 		return r;
-- 
2.50.1.565.gc32cd1483b-goog