linux-kernel - [RFC PATCH 03/24] KVM: SVM: Add helpers to set/clear ASID flush in VMCB

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Message-ID: <20250326193619.3714986-4-yosry.ahmed@linux.dev>
Date: Wed, 26 Mar 2025 19:35:58 +0000
From: Yosry Ahmed <yosry.ahmed@...ux.dev>
To: Sean Christopherson <seanjc@...gle.com>
Cc: Paolo Bonzini <pbonzini@...hat.com>,
	Jim Mattson <jmattson@...gle.com>,
	Maxim Levitsky <mlevitsk@...hat.com>,
	Vitaly Kuznetsov <vkuznets@...hat.com>,
	Rik van Riel <riel@...riel.com>,
	Tom Lendacky <thomas.lendacky@....com>,
	x86@...nel.org,
	kvm@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Yosry Ahmed <yosry.ahmed@...ux.dev>
Subject: [RFC PATCH 03/24] KVM: SVM: Add helpers to set/clear ASID flush in VMCB

Incoming changes will add more code paths that set tlb_ctl to
TLB_CONTROL_FLUSH_ASID, and will eliminate the use of
TLB_CONTROL_FLUSH_ALL_ASID except as fallback when FLUSHBYASID is not
available. Introduce set/clear helpers to set tlb_ctl to
TLB_CONTROL_FLUSH_ASID or TLB_CONTROL_DO_NOTHING.

Opportunistically move the TLB_CONTROL_* definitions to
arch/x86/kvm/svm/svm.h as they are not used outside of arch/x86/kvm/svm/.

Signed-off-by: Yosry Ahmed <yosry.ahmed@...ux.dev>
---
 arch/x86/include/asm/svm.h |  5 -----
 arch/x86/kvm/svm/nested.c  |  2 +-
 arch/x86/kvm/svm/sev.c     |  2 +-
 arch/x86/kvm/svm/svm.c     |  4 ++--
 arch/x86/kvm/svm/svm.h     | 15 +++++++++++++++
 5 files changed, 19 insertions(+), 9 deletions(-)

diff --git a/arch/x86/include/asm/svm.h b/arch/x86/include/asm/svm.h
index 9b7fa99ae9513..a97da63562eb3 100644
--- a/arch/x86/include/asm/svm.h
+++ b/arch/x86/include/asm/svm.h
@@ -171,11 +171,6 @@ struct __attribute__ ((__packed__)) vmcb_control_area {
 };
 
 
-#define TLB_CONTROL_DO_NOTHING 0
-#define TLB_CONTROL_FLUSH_ALL_ASID 1
-#define TLB_CONTROL_FLUSH_ASID 3
-#define TLB_CONTROL_FLUSH_ASID_LOCAL 7
-
 #define V_TPR_MASK 0x0f
 
 #define V_IRQ_SHIFT 8
diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c
index 834b67672d50f..11b02a0340d9e 100644
--- a/arch/x86/kvm/svm/nested.c
+++ b/arch/x86/kvm/svm/nested.c
@@ -681,7 +681,7 @@ static void nested_vmcb02_prepare_control(struct vcpu_svm *svm,
 	/* Done at vmrun: asid.  */
 
 	/* Also overwritten later if necessary.  */
-	vmcb02->control.tlb_ctl = TLB_CONTROL_DO_NOTHING;
+	vmcb_clr_flush_asid(vmcb02);
 
 	/* nested_cr3.  */
 	if (nested_npt_enabled(svm))
diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index 0bc708ee27887..d613f81addf1c 100644
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -3479,7 +3479,7 @@ int pre_sev_run(struct vcpu_svm *svm, int cpu)
 		return 0;
 
 	sd->sev_vmcbs[asid] = svm->vmcb;
-	svm->vmcb->control.tlb_ctl = TLB_CONTROL_FLUSH_ASID;
+	vmcb_set_flush_asid(svm->vmcb);
 	vmcb_mark_dirty(svm->vmcb, VMCB_ASID);
 	return 0;
 }
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index 28a6d2c0f250f..0e302ae9a8435 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -4006,7 +4006,7 @@ static void svm_flush_tlb_asid(struct kvm_vcpu *vcpu)
 	 * VM-Exit (via kvm_mmu_reset_context()).
 	 */
 	if (static_cpu_has(X86_FEATURE_FLUSHBYASID))
-		svm->vmcb->control.tlb_ctl = TLB_CONTROL_FLUSH_ASID;
+		vmcb_set_flush_asid(svm->vmcb);
 	else
 		svm->current_vmcb->asid_generation--;
 }
@@ -4373,7 +4373,7 @@ static __no_kcsan fastpath_t svm_vcpu_run(struct kvm_vcpu *vcpu,
 		svm->nested.nested_run_pending = 0;
 	}
 
-	svm->vmcb->control.tlb_ctl = TLB_CONTROL_DO_NOTHING;
+	vmcb_clr_flush_asid(svm->vmcb);
 	vmcb_mark_all_clean(svm->vmcb);
 
 	/* if exit due to PF check for async PF */
diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h
index d4490eaed55dd..d2c49cbfbf1ca 100644
--- a/arch/x86/kvm/svm/svm.h
+++ b/arch/x86/kvm/svm/svm.h
@@ -409,6 +409,21 @@ static inline bool vmcb_is_dirty(struct vmcb *vmcb, int bit)
         return !test_bit(bit, (unsigned long *)&vmcb->control.clean);
 }
 
+#define TLB_CONTROL_DO_NOTHING 0
+#define TLB_CONTROL_FLUSH_ALL_ASID 1
+#define TLB_CONTROL_FLUSH_ASID 3
+#define TLB_CONTROL_FLUSH_ASID_LOCAL 7
+
+static inline void vmcb_set_flush_asid(struct vmcb *vmcb)
+{
+	vmcb->control.tlb_ctl = TLB_CONTROL_FLUSH_ASID;
+}
+
+static inline void vmcb_clr_flush_asid(struct vmcb *vmcb)
+{
+	vmcb->control.tlb_ctl = TLB_CONTROL_DO_NOTHING;
+}
+
 static __always_inline struct vcpu_svm *to_svm(struct kvm_vcpu *vcpu)
 {
 	return container_of(vcpu, struct vcpu_svm, vcpu);
-- 
2.49.0.395.g12beb8f557-goog