KVM: x86: hyper-v: Resurrect dedicated KVM_REQ_HV_TLB_FLUSH flag

In preparation to implementing fine-grained Hyper-V TLB flush and
L2 TLB flush, resurrect dedicated KVM_REQ_HV_TLB_FLUSH request bit. As
KVM_REQ_TLB_FLUSH_GUEST is a stronger operation, clear KVM_REQ_HV_TLB_FLUSH
request in kvm_vcpu_flush_tlb_guest().

The flush itself is temporary handled by kvm_vcpu_flush_tlb_guest().

No functional change intended.

Reviewed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20221101145426.251680-9-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index a413f841e83080d19c5053e01da9d92c50232a04..0b85230a0e0a7a126a57b54b36601d16c7a734b9 100644 (file)
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -110,6 +110,8 @@
        KVM_ARCH_REQ_FLAGS(30, KVM_REQUEST_WAIT | KVM_REQUEST_NO_WAKEUP)
 #define KVM_REQ_MMU_FREE_OBSOLETE_ROOTS \
        KVM_ARCH_REQ_FLAGS(31, KVM_REQUEST_WAIT | KVM_REQUEST_NO_WAKEUP)
+#define KVM_REQ_HV_TLB_FLUSH \
+       KVM_ARCH_REQ_FLAGS(32, KVM_REQUEST_WAIT | KVM_REQUEST_NO_WAKEUP)
 
 #define CR0_RESERVED_BITS                                               \
        (~(unsigned long)(X86_CR0_PE | X86_CR0_MP | X86_CR0_EM | X86_CR0_TS \

diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c
index 0adf4a437e85f6f7e67b7b281ebc2484b680ee2f..3c0f639f6a05e7ac2fe077277c132e2e01f33f22 100644 (file)
--- a/arch/x86/kvm/hyperv.c
+++ b/arch/x86/kvm/hyperv.c
@@ -1870,11 +1870,11 @@ static u64 kvm_hv_flush_tlb(struct kvm_vcpu *vcpu, struct kvm_hv_hcall *hc)
         * analyze it here, flush TLB regardless of the specified address space.
         */
        if (all_cpus) {
-               kvm_make_all_cpus_request(kvm, KVM_REQ_TLB_FLUSH_GUEST);
+               kvm_make_all_cpus_request(kvm, KVM_REQ_HV_TLB_FLUSH);
        } else {
                sparse_set_to_vcpu_mask(kvm, sparse_banks, valid_bank_mask, vcpu_mask);
 
-               kvm_make_vcpus_request_mask(kvm, KVM_REQ_TLB_FLUSH_GUEST, vcpu_mask);
+               kvm_make_vcpus_request_mask(kvm, KVM_REQ_HV_TLB_FLUSH, vcpu_mask);
        }
 
 ret_success:

diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index 7efc4fdaa446ba7fa2bb6c17099c945ec76f8706..4ea6ddd9989947eadf5376702112c9727328d787 100644 (file)
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -3722,6 +3722,13 @@ static void svm_flush_tlb_current(struct kvm_vcpu *vcpu)
 {
        struct vcpu_svm *svm = to_svm(vcpu);
 
+       /*
+        * Unlike VMX, SVM doesn't provide a way to flush only NPT TLB entries.
+        * A TLB flush for the current ASID flushes both "host" and "guest" TLB
+        * entries, and thus is a superset of Hyper-V's fine grained flushing.
+        */
+       kvm_clear_request(KVM_REQ_HV_TLB_FLUSH, vcpu);
+
        /*
         * Flush only the current ASID even if the TLB flush was invoked via
         * kvm_flush_remote_tlbs().  Although flushing remote TLBs requires all

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 7fc5508c0b4a95b5a105e6e51ac8a5900d4e6135..12e49e8566d498229fd84fefd01e7b209a39bc1d 100644 (file)
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -3420,6 +3420,12 @@ static void kvm_vcpu_flush_tlb_guest(struct kvm_vcpu *vcpu)
        }
 
        static_call(kvm_x86_flush_tlb_guest)(vcpu);
+
+       /*
+        * Flushing all "guest" TLB is always a superset of Hyper-V's fine
+        * grained flushing.
+        */
+       kvm_clear_request(KVM_REQ_HV_TLB_FLUSH, vcpu);
 }
 
 
@@ -10250,6 +10256,9 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu)
 
                kvm_service_local_tlb_flush_requests(vcpu);
 
+               if (kvm_check_request(KVM_REQ_HV_TLB_FLUSH, vcpu))
+                       kvm_vcpu_flush_tlb_guest(vcpu);
+
                if (kvm_check_request(KVM_REQ_REPORT_TPR_ACCESS, vcpu)) {
                        vcpu->run->exit_reason = KVM_EXIT_TPR_ACCESS;
                        r = 0;