diff options
| author | Paolo Bonzini <pbonzini@redhat.com> | 2018-07-02 13:07:14 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2018-08-15 18:14:48 +0200 |
| commit | b3dc63c4f43e57d73d769ad0d3f34eae74cb68a8 (patch) | |
| tree | 9f8680294f6cb43985c0038a021a477f81f9d256 /arch/x86/kvm/vmx.c | |
| parent | acca8a70a5f6179007e1148a62b8bef12b212d9b (diff) | |
x86/KVM/VMX: Add L1D flush logic
commit c595ceee45707f00f64f61c54fb64ef0cc0b4e85 upstream
Add the logic for flushing L1D on VMENTER. The flush depends on the static
key being enabled and the new l1tf_flush_l1d flag being set.
The flags is set:
- Always, if the flush module parameter is 'always'
- Conditionally at:
- Entry to vcpu_run(), i.e. after executing user space
- From the sched_in notifier, i.e. when switching to a vCPU thread.
- From vmexit handlers which are considered unsafe, i.e. where
sensitive data can be brought into L1D:
- The emulator, which could be a good target for other speculative
execution-based threats,
- The MMU, which can bring host page tables in the L1 cache.
- External interrupts
- Nested operations that require the MMU (see above). That is
vmptrld, vmptrst, vmclear,vmwrite,vmread.
- When handling invept,invvpid
[ tglx: Split out from combo patch and reduced to a single flag ]
[ dwmw2: Backported to 4.9, set l1tf_flush_l1d in svm/vmx code ]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'arch/x86/kvm/vmx.c')
| -rw-r--r-- | arch/x86/kvm/vmx.c | 23 |
1 files changed, 22 insertions, 1 deletions
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c index 28b823362580..1918a124f576 100644 --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -5773,6 +5773,7 @@ static int handle_exception(struct kvm_vcpu *vcpu) BUG_ON(enable_ept); cr2 = vmcs_readl(EXIT_QUALIFICATION); trace_kvm_page_fault(cr2, error_code); + vcpu->arch.l1tf_flush_l1d = true; if (kvm_event_needs_reinjection(vcpu)) kvm_mmu_unprotect_page_virt(vcpu, cr2); @@ -8549,9 +8550,20 @@ static int vmx_handle_exit(struct kvm_vcpu *vcpu) #define L1D_CACHE_ORDER 4 static void *vmx_l1d_flush_pages; -static void __maybe_unused vmx_l1d_flush(void) +static void vmx_l1d_flush(struct kvm_vcpu *vcpu) { int size = PAGE_SIZE << L1D_CACHE_ORDER; + bool always; + + /* + * If the mitigation mode is 'flush always', keep the flush bit + * set, otherwise clear it. It gets set again either from + * vcpu_run() or from one of the unsafe VMEXIT handlers. + */ + always = vmentry_l1d_flush == VMENTER_L1D_FLUSH_ALWAYS; + vcpu->arch.l1tf_flush_l1d = always; + + vcpu->stat.l1d_flush++; if (static_cpu_has(X86_FEATURE_FLUSH_L1D)) { wrmsrl(MSR_IA32_FLUSH_CMD, L1D_FLUSH); @@ -8792,6 +8804,7 @@ static void vmx_handle_external_intr(struct kvm_vcpu *vcpu) [ss]"i"(__KERNEL_DS), [cs]"i"(__KERNEL_CS) ); + vcpu->arch.l1tf_flush_l1d = true; } } STACK_FRAME_NON_STANDARD(vmx_handle_external_intr); @@ -9037,6 +9050,11 @@ static void __noclone vmx_vcpu_run(struct kvm_vcpu *vcpu) vmx->__launched = vmx->loaded_vmcs->launched; + if (static_branch_unlikely(&vmx_l1d_should_flush)) { + if (vcpu->arch.l1tf_flush_l1d) + vmx_l1d_flush(vcpu); + } + asm( /* Store host registers */ "push %%" _ASM_DX "; push %%" _ASM_BP ";" @@ -10552,6 +10570,9 @@ static int nested_vmx_run(struct kvm_vcpu *vcpu, bool launch) vmcs12->launch_state = 1; + /* Hide L1D cache contents from the nested guest. */ + vmx->vcpu.arch.l1tf_flush_l1d = true; + if (vmcs12->guest_activity_state == GUEST_ACTIVITY_HLT) return kvm_vcpu_halt(vcpu); |