RISC-V: KVM: Cleanup stale TLB entries when host CPU changes

On RISC-V platforms with hardware VMID support, we share same
VMID for all VCPUs of a particular Guest/VM. This means we might
have stale G-stage TLB entries on the current Host CPU due to
some other VCPU of the same Guest which ran previously on the
current Host CPU.

To cleanup stale TLB entries, we simply flush all G-stage TLB
entries by VMID whenever underlying Host CPU changes for a VCPU.

Signed-off-by: Anup Patel <apatel@ventanamicro.com>
Reviewed-by: Atish Patra <atishp@rivosinc.com>
Signed-off-by: Anup Patel <anup@brainfault.org>

1 files changed, 11 insertions, 0 deletions

diff --git a/arch/riscv/kvm/vcpu.c b/arch/riscv/kvm/vcpu.c
index 88b8c0fb5f5e..a7c8400f16b5 100644
--- a/arch/riscv/kvm/vcpu.c
+++ b/arch/riscv/kvm/vcpu.c
@@ -67,6 +67,8 @@ static void kvm_riscv_reset_vcpu(struct kvm_vcpu *vcpu)
 	if (loaded)
 		kvm_arch_vcpu_put(vcpu);
 
+	vcpu->arch.last_exit_cpu = -1;
+
 	memcpy(csr, reset_csr, sizeof(*csr));
 
 	memcpy(cntx, reset_cntx, sizeof(*cntx));
@@ -735,6 +737,7 @@ static void noinstr kvm_riscv_vcpu_enter_exit(struct kvm_vcpu *vcpu)
 {
 	guest_state_enter_irqoff();
 	__kvm_riscv_switch_to(&vcpu->arch);
+	vcpu->arch.last_exit_cpu = vcpu->cpu;
 	guest_state_exit_irqoff();
 }
 
@@ -829,6 +832,14 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu)
 			continue;
 		}
 
+		/*
+		 * Cleanup stale TLB enteries
+		 *
+		 * Note: This should be done after G-stage VMID has been
+		 * updated using kvm_riscv_gstage_vmid_ver_changed()
+		 */
+		kvm_riscv_local_tlb_sanitize(vcpu);
+
 		guest_timing_enter_irqoff();
 
 		kvm_riscv_vcpu_enter_exit(vcpu);