linux-kernel - [PATCH v6 37/44] KVM: VMX: Dedup code for removing MSR from VMCS's auto-load list

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Message-ID: <20251206001720.468579-38-seanjc@google.com>
Date: Fri,  5 Dec 2025 16:17:13 -0800
From: Sean Christopherson <seanjc@...gle.com>
To: Marc Zyngier <maz@...nel.org>, Oliver Upton <oupton@...nel.org>, 
	Tianrui Zhao <zhaotianrui@...ngson.cn>, Bibo Mao <maobibo@...ngson.cn>, 
	Huacai Chen <chenhuacai@...nel.org>, Anup Patel <anup@...infault.org>, 
	Paul Walmsley <pjw@...nel.org>, 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, Mingwei Zhang <mizhang@...gle.com>, 
	Xudong Hao <xudong.hao@...el.com>, Sandipan Das <sandipan.das@....com>, 
	Dapeng Mi <dapeng1.mi@...ux.intel.com>, Xiong Zhang <xiong.y.zhang@...ux.intel.com>, 
	Manali Shukla <manali.shukla@....com>, Jim Mattson <jmattson@...gle.com>
Subject: [PATCH v6 37/44] KVM: VMX: Dedup code for removing MSR from VMCS's
 auto-load list

Add a helper to remove an MSR from an auto-{load,store} list to dedup the
msr_autoload code, and in anticipation of adding similar functionality for
msr_autostore.

No functional change intended.

Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 arch/x86/kvm/vmx/vmx.c | 31 ++++++++++++++++---------------
 1 file changed, 16 insertions(+), 15 deletions(-)

diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 52bcb817cc15..a51f66d1b201 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -1040,9 +1040,22 @@ static int vmx_find_loadstore_msr_slot(struct vmx_msrs *m, u32 msr)
 	return -ENOENT;
 }
 
+static void vmx_remove_auto_msr(struct vmx_msrs *m, u32 msr,
+				unsigned long vmcs_count_field)
+{
+	int i;
+
+	i = vmx_find_loadstore_msr_slot(m, msr);
+	if (i < 0)
+		return;
+
+	--m->nr;
+	m->val[i] = m->val[m->nr];
+	vmcs_write32(vmcs_count_field, m->nr);
+}
+
 static void clear_atomic_switch_msr(struct vcpu_vmx *vmx, unsigned msr)
 {
-	int i;
 	struct msr_autoload *m = &vmx->msr_autoload;
 
 	switch (msr) {
@@ -1063,21 +1076,9 @@ static void clear_atomic_switch_msr(struct vcpu_vmx *vmx, unsigned msr)
 		}
 		break;
 	}
-	i = vmx_find_loadstore_msr_slot(&m->guest, msr);
-	if (i < 0)
-		goto skip_guest;
-	--m->guest.nr;
-	m->guest.val[i] = m->guest.val[m->guest.nr];
-	vmcs_write32(VM_ENTRY_MSR_LOAD_COUNT, m->guest.nr);
 
-skip_guest:
-	i = vmx_find_loadstore_msr_slot(&m->host, msr);
-	if (i < 0)
-		return;
-
-	--m->host.nr;
-	m->host.val[i] = m->host.val[m->host.nr];
-	vmcs_write32(VM_EXIT_MSR_LOAD_COUNT, m->host.nr);
+	vmx_remove_auto_msr(&m->guest, msr, VM_ENTRY_MSR_LOAD_COUNT);
+	vmx_remove_auto_msr(&m->host, msr, VM_EXIT_MSR_LOAD_COUNT);
 }
 
 static __always_inline void add_atomic_switch_msr_special(struct vcpu_vmx *vmx,
-- 
2.52.0.223.gf5cc29aaa4-goog