From: Sean Christopherson <seanjc@xxxxxxxxxx>
[ Upstream commit 07ffaf343e34b555c9e7ea39a9c81c439a706f13 ]
Trigger a full TLB flush on behalf of the guest on nested VM-Enter and
VM-Exit when VPID is disabled for L2. kvm_mmu_new_pgd() syncs only the
current PGD, which can theoretically leave stale, unsync'd entries in a
previous guest PGD, which could be consumed if L2 is allowed to load CR3
with PCID_NOFLUSH=1.
Rename KVM_REQ_HV_TLB_FLUSH to KVM_REQ_TLB_FLUSH_GUEST so that it can
be utilized for its obvious purpose of emulating a guest TLB flush.
Note, there is no change the actual TLB flush executed by KVM, even
though the fast PGD switch uses KVM_REQ_TLB_FLUSH_CURRENT. When VPID is
disabled for L2, vpid02 is guaranteed to be '0', and thus
nested_get_vpid02() will return the VPID that is shared by L1 and L2.
Generate the request outside of kvm_mmu_new_pgd(), as getting the common
helper to correctly identify which requested is needed is quite painful.
E.g. using KVM_REQ_TLB_FLUSH_GUEST when nested EPT is in play is wrong as
a TLB flush from the L1 kernel's perspective does not invalidate EPT
mappings. And, by using KVM_REQ_TLB_FLUSH_GUEST, nVMX can do future
simplification by moving the logic into nested_vmx_transition_tlb_flush().
Fixes: 41fab65e7c44 ("KVM: nVMX: Skip MMU sync on nested VMX transition when possible")
Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
Message-Id: <20210609234235.1244004-2-seanjc@xxxxxxxxxx>
Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
arch/x86/include/asm/kvm_host.h | 2 +-
arch/x86/kvm/hyperv.c | 2 +-
arch/x86/kvm/vmx/nested.c | 17 ++++++++++++-----
arch/x86/kvm/x86.c | 2 +-
4 files changed, 15 insertions(+), 8 deletions(-)
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 0702adf2460b..0758ff3008c6 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -85,7 +85,7 @@
#define KVM_REQ_APICV_UPDATE \
KVM_ARCH_REQ_FLAGS(25, KVM_REQUEST_WAIT | KVM_REQUEST_NO_WAKEUP)
#define KVM_REQ_TLB_FLUSH_CURRENT KVM_ARCH_REQ(26)
-#define KVM_REQ_HV_TLB_FLUSH \
+#define KVM_REQ_TLB_FLUSH_GUEST \
KVM_ARCH_REQ_FLAGS(27, KVM_REQUEST_NO_WAKEUP)
#define KVM_REQ_APF_READY KVM_ARCH_REQ(28)
#define KVM_REQ_MSR_FILTER_CHANGED KVM_ARCH_REQ(29)
diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c
index f00830e5202f..fdd1eca717fd 100644
--- a/arch/x86/kvm/hyperv.c
+++ b/arch/x86/kvm/hyperv.c
@@ -1704,7 +1704,7 @@ static u64 kvm_hv_flush_tlb(struct kvm_vcpu *vcpu, u64 ingpa, u16 rep_cnt, bool
* vcpu->arch.cr3 may not be up-to-date for running vCPUs so we can't
* analyze it here, flush TLB regardless of the specified address space.
*/
- kvm_make_vcpus_request_mask(kvm, KVM_REQ_HV_TLB_FLUSH,
+ kvm_make_vcpus_request_mask(kvm, KVM_REQ_TLB_FLUSH_GUEST,
NULL, vcpu_mask, &hv_vcpu->tlb_flush);
ret_success:
diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index 8cb5a95e0c54..eca3db08d183 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -1132,12 +1132,19 @@ static int nested_vmx_load_cr3(struct kvm_vcpu *vcpu, unsigned long cr3, bool ne
/*
* Unconditionally skip the TLB flush on fast CR3 switch, all TLB
- * flushes are handled by nested_vmx_transition_tlb_flush(). See
- * nested_vmx_transition_mmu_sync for details on skipping the MMU sync.
+ * flushes are handled by nested_vmx_transition_tlb_flush().
*/
- if (!nested_ept)
- kvm_mmu_new_pgd(vcpu, cr3, true,
- !nested_vmx_transition_mmu_sync(vcpu));
+ if (!nested_ept) {
+ kvm_mmu_new_pgd(vcpu, cr3, true, true);
+
+ /*
+ * A TLB flush on VM-Enter/VM-Exit flushes all linear mappings
+ * across all PCIDs, i.e. all PGDs need to be synchronized.
+ * See nested_vmx_transition_mmu_sync() for more details.
+ */
+ if (nested_vmx_transition_mmu_sync(vcpu))
+ kvm_make_request(KVM_REQ_TLB_FLUSH_GUEST, vcpu);
+ }
vcpu->arch.cr3 = cr3;
kvm_register_mark_available(vcpu, VCPU_EXREG_CR3);
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index d46a6182d0e9..615dd236e842 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -9022,7 +9022,7 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu)
}
if (kvm_check_request(KVM_REQ_TLB_FLUSH_CURRENT, vcpu))
kvm_vcpu_flush_tlb_current(vcpu);
- if (kvm_check_request(KVM_REQ_HV_TLB_FLUSH, vcpu))
+ if (kvm_check_request(KVM_REQ_TLB_FLUSH_GUEST, vcpu))
kvm_vcpu_flush_tlb_guest(vcpu);
if (kvm_check_request(KVM_REQ_REPORT_TPR_ACCESS, vcpu)) {
--
2.30.2
