[PATCH 2/2] KVM: nSVM: Track the ASID generation of the vmcb vmrun through the vmcb

From: Cathy Avery <hidden>
Date: 2021-01-12 16:45:22
Also in: lkml
Subsystem: kernel virtual machine for x86 (kvm/x86), the rest, x86 architecture (32-bit and 64-bit) · Maintainers: Sean Christopherson, Paolo Bonzini, Linus Torvalds, Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen

This patch moves the asid_generation from the vcpu to the vmcb
in order to track the ASID generation that was active the last
time the vmcb was run. If sd->asid_generation changes between
two runs, the old ASID is invalid and must be changed.

Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Cathy Avery <redacted>
---
 arch/x86/kvm/svm/svm.c | 21 +++++++--------------
 arch/x86/kvm/svm/svm.h |  2 +-
 2 files changed, 8 insertions(+), 15 deletions(-)

diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index 5b6998ff7aa1..73e63f7a0acf 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c

@@ -1214,7 +1214,7 @@ static void init_vmcb(struct vcpu_svm *svm)
 		save->cr3 = 0;
 		save->cr4 = 0;
 	}
-	svm->asid_generation = 0;
+	svm->current_vmcb->asid_generation = 0;
 	svm->asid = 0;
 
 	svm->nested.vmcb12_gpa = 0;

@@ -1296,13 +1296,6 @@ void svm_switch_vmcb(struct vcpu_svm *svm, struct kvm_vmcb_info *target_vmcb)
 	svm->vmcb = target_vmcb->ptr;
 	svm->vmcb_pa = target_vmcb->pa;
 
-	/*
-	* Workaround: we don't yet track the ASID generation
-	* that was active the last time target_vmcb was run.
-	*/
-
-	svm->asid_generation = 0;
-
 	/*
 	* Track the physical CPU the target_vmcb is running on
 	* in order to mark the VMCB dirty if the cpu changes at

@@ -1347,7 +1340,6 @@ static int svm_create_vcpu(struct kvm_vcpu *vcpu)
 
 	svm_switch_vmcb(svm, &svm->vmcb01);
 
-	svm->asid_generation = 0;
 	init_vmcb(svm);
 
 	svm_init_osvw(vcpu);

@@ -1784,7 +1776,7 @@ static void new_asid(struct vcpu_svm *svm, struct svm_cpu_data *sd)
 		vmcb_mark_dirty(svm->vmcb, VMCB_ASID);
 	}
 
-	svm->asid_generation = sd->asid_generation;
+	svm->current_vmcb->asid_generation = sd->asid_generation;
 	svm->asid = sd->next_asid++;
 }

@@ -3179,11 +3171,12 @@ static void pre_svm_run(struct vcpu_svm *svm)
 
 	/*
 	* If the previous vmrun of the vmcb occurred on
-	* a different physical cpu then we must mark the vmcb dirty.
+	* a different physical cpu then we must mark the vmcb dirty,
+	* update the asid_generation, and assign a new asid.
 	*/
 
         if (unlikely(svm->current_vmcb->cpu != svm->vcpu.cpu)) {
-		svm->asid_generation = 0;
+		svm->current_vmcb->asid_generation = 0;
 		vmcb_mark_all_dirty(svm->vmcb);
 		svm->current_vmcb->cpu = svm->vcpu.cpu;
         }

@@ -3192,7 +3185,7 @@ static void pre_svm_run(struct vcpu_svm *svm)
 		return pre_sev_run(svm, svm->vcpu.cpu);
 
 	/* FIXME: handle wraparound of asid_generation */
-	if (svm->asid_generation != sd->asid_generation)
+	if (svm->current_vmcb->asid_generation != sd->asid_generation)
 		new_asid(svm, sd);
 }

@@ -3399,7 +3392,7 @@ void svm_flush_tlb(struct kvm_vcpu *vcpu)
 	if (static_cpu_has(X86_FEATURE_FLUSHBYASID))
 		svm->vmcb->control.tlb_ctl = TLB_CONTROL_FLUSH_ASID;
 	else
-		svm->asid_generation--;
+		svm->current_vmcb->asid_generation--;
 }
 
 static void svm_flush_tlb_gva(struct kvm_vcpu *vcpu, gva_t gva)

diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h
index 05baee934d03..edcfc2a4e77e 100644
--- a/arch/x86/kvm/svm/svm.h
+++ b/arch/x86/kvm/svm/svm.h

@@ -86,6 +86,7 @@ struct kvm_vmcb_info {
 	struct vmcb *ptr;
 	unsigned long pa;
 	int cpu;
+	uint64_t asid_generation;
 };
 
 struct svm_nested_state {

@@ -115,7 +116,6 @@ struct vcpu_svm {
 	struct kvm_vmcb_info *current_vmcb;
 	struct svm_cpu_data *svm_data;
 	u32 asid;
-	uint64_t asid_generation;
 	uint64_t sysenter_esp;
 	uint64_t sysenter_eip;
 	uint64_t tsc_aux;

-- 
2.20.1

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