linux-kernel - [PATCH 3/7] KVM: SVM: Add helpers to set/clear ASID flush

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Message-ID: <20250313215540.4171762-4-yosry.ahmed@linux.dev>
Date: Thu, 13 Mar 2025 21:55:36 +0000
From: Yosry Ahmed <yosry.ahmed@...ux.dev>
To: Sean Christopherson <seanjc@...gle.com>
Cc: Paolo Bonzini <pbonzini@...hat.com>,
	Maxim Levitsky <mlevitsk@...hat.com>,
	x86@...nel.org,
	kvm@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Yosry Ahmed <yosry.ahmed@...ux.dev>
Subject: [PATCH 3/7] KVM: SVM: Add helpers to set/clear ASID flush

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..3bff948bc5752 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;
+	svm_vmcb_clear_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..b393674733969 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;
+	svm_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..8c90686a33f44 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;
+		svm_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;
+	svm_vmcb_clear_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..9fd5b249b9c19 100644
--- a/arch/x86/kvm/svm/svm.h
+++ b/arch/x86/kvm/svm/svm.h
@@ -638,6 +638,21 @@ void svm_set_x2apic_msr_interception(struct vcpu_svm *svm, bool disable);
 void svm_complete_interrupt_delivery(struct kvm_vcpu *vcpu, int delivery_mode,
 				     int trig_mode, int vec);
 
+#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 svm_vmcb_set_flush_asid(struct vmcb *vmcb)
+{
+	vmcb->control.tlb_ctl = TLB_CONTROL_FLUSH_ASID;
+}
+
+static inline void svm_vmcb_clear_flush_asid(struct vmcb *vmcb)
+{
+	vmcb->control.tlb_ctl = TLB_CONTROL_DO_NOTHING;
+}
+
 /* nested.c */
 
 #define NESTED_EXIT_HOST	0	/* Exit handled on host level */
-- 
2.49.0.rc1.451.g8f38331e32-goog