From: Sean Christopherson <seanjc@google.com>
To: Sean Christopherson <seanjc@google.com>,
Paolo Bonzini <pbonzini@redhat.com>
Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
Jim Mattson <jmattson@google.com>,
Maxim Levitsky <mlevitsk@redhat.com>,
Oliver Upton <oupton@google.com>, Peter Shier <pshier@google.com>
Subject: [PATCH v5 05/27] KVM: x86: Suppress code #DBs on Intel if MOV/POP SS blocking is active
Date: Tue, 30 Aug 2022 23:15:52 +0000 [thread overview]
Message-ID: <20220830231614.3580124-6-seanjc@google.com> (raw)
In-Reply-To: <20220830231614.3580124-1-seanjc@google.com>
Suppress code breakpoints if MOV/POP SS blocking is active and the guest
CPU is Intel, i.e. if the guest thinks it's running on an Intel CPU.
Intel CPUs inhibit code #DBs when MOV/POP SS blocking is active, whereas
AMD (and its descendents) do not.
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
arch/x86/kvm/x86.c | 19 ++++++++++++++++++-
1 file changed, 18 insertions(+), 1 deletion(-)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 7403221c868e..013580c355d7 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -8542,6 +8542,23 @@ int kvm_skip_emulated_instruction(struct kvm_vcpu *vcpu)
}
EXPORT_SYMBOL_GPL(kvm_skip_emulated_instruction);
+static bool kvm_is_code_breakpoint_inhibited(struct kvm_vcpu *vcpu)
+{
+ u32 shadow;
+
+ if (kvm_get_rflags(vcpu) & X86_EFLAGS_RF)
+ return true;
+
+ /*
+ * Intel CPUs inhibit code #DBs when MOV/POP SS blocking is active,
+ * but AMD CPUs do not. MOV/POP SS blocking is rare, check that first
+ * to avoid the relatively expensive CPUID lookup.
+ */
+ shadow = static_call(kvm_x86_get_interrupt_shadow)(vcpu);
+ return (shadow & KVM_X86_SHADOW_INT_MOV_SS) &&
+ guest_cpuid_is_intel(vcpu);
+}
+
static bool kvm_vcpu_check_code_breakpoint(struct kvm_vcpu *vcpu,
int emulation_type, int *r)
{
@@ -8584,7 +8601,7 @@ static bool kvm_vcpu_check_code_breakpoint(struct kvm_vcpu *vcpu,
}
if (unlikely(vcpu->arch.dr7 & DR7_BP_EN_MASK) &&
- !(kvm_get_rflags(vcpu) & X86_EFLAGS_RF)) {
+ !kvm_is_code_breakpoint_inhibited(vcpu)) {
unsigned long eip = kvm_get_linear_rip(vcpu);
u32 dr6 = kvm_vcpu_check_hw_bp(eip, 0,
vcpu->arch.dr7,
--
2.37.2.672.g94769d06f0-goog
next prev parent reply other threads:[~2022-08-30 23:17 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-08-30 23:15 [PATCH v5 00/27] KVM: x86: Event/exception fixes and cleanups Sean Christopherson
2022-08-30 23:15 ` [PATCH v5 01/27] KVM: nVMX: Unconditionally purge queued/injected events on nested "exit" Sean Christopherson
2022-08-30 23:15 ` [PATCH v5 02/27] KVM: VMX: Drop bits 31:16 when shoving exception error code into VMCS Sean Christopherson
2022-08-30 23:15 ` [PATCH v5 03/27] KVM: x86: Don't check for code breakpoints when emulating on exception Sean Christopherson
2022-08-30 23:15 ` [PATCH v5 04/27] KVM: x86: Allow clearing RFLAGS.RF on forced emulation to test code #DBs Sean Christopherson
2022-08-30 23:15 ` Sean Christopherson [this message]
2022-08-30 23:15 ` [PATCH v5 06/27] KVM: nVMX: Treat General Detect #DB (DR7.GD=1) as fault-like Sean Christopherson
2022-08-30 23:15 ` [PATCH v5 07/27] KVM: nVMX: Prioritize TSS T-flag #DBs over Monitor Trap Flag Sean Christopherson
2022-08-30 23:15 ` [PATCH v5 08/27] KVM: x86: Treat #DBs from the emulator as fault-like (code and DR7.GD=1) Sean Christopherson
2022-08-30 23:15 ` [PATCH v5 09/27] KVM: x86: Use DR7_GD macro instead of open coding check in emulator Sean Christopherson
2022-08-30 23:15 ` [PATCH v5 10/27] KVM: nVMX: Ignore SIPI that arrives in L2 when vCPU is not in WFS Sean Christopherson
2022-08-30 23:15 ` [PATCH v5 11/27] KVM: nVMX: Unconditionally clear mtf_pending on nested VM-Exit Sean Christopherson
2022-08-30 23:15 ` [PATCH v5 12/27] KVM: VMX: Inject #PF on ENCLS as "emulated" #PF Sean Christopherson
2022-08-30 23:16 ` [PATCH v5 13/27] KVM: x86: Rename kvm_x86_ops.queue_exception to inject_exception Sean Christopherson
2022-08-30 23:16 ` [PATCH v5 14/27] KVM: x86: Make kvm_queued_exception a properly named, visible struct Sean Christopherson
2022-08-30 23:16 ` [PATCH v5 15/27] KVM: x86: Formalize blocking of nested pending exceptions Sean Christopherson
2022-08-30 23:16 ` [PATCH v5 16/27] KVM: x86: Use kvm_queue_exception_e() to queue #DF Sean Christopherson
2022-08-30 23:16 ` [PATCH v5 17/27] KVM: x86: Hoist nested event checks above event injection logic Sean Christopherson
2022-08-30 23:16 ` [PATCH v5 18/27] KVM: x86: Evaluate ability to inject SMI/NMI/IRQ after potential VM-Exit Sean Christopherson
2022-08-30 23:16 ` [PATCH v5 19/27] KVM: nVMX: Add a helper to identify low-priority #DB traps Sean Christopherson
2022-08-30 23:16 ` [PATCH v5 20/27] KVM: nVMX: Document priority of all known events on Intel CPUs Sean Christopherson
2022-08-30 23:16 ` [PATCH v5 21/27] KVM: x86: Morph pending exceptions to pending VM-Exits at queue time Sean Christopherson
2022-08-30 23:16 ` [PATCH v5 22/27] KVM: x86: Treat pending TRIPLE_FAULT requests as pending exceptions Sean Christopherson
2022-08-30 23:16 ` [PATCH v5 23/27] KVM: VMX: Update MTF and ICEBP comments to document KVM's subtle behavior Sean Christopherson
2022-08-30 23:16 ` [PATCH v5 24/27] KVM: x86: Rename inject_pending_events() to kvm_check_and_inject_events() Sean Christopherson
2022-08-30 23:16 ` [PATCH v5 25/27] KVM: selftests: Use uapi header to get VMX and SVM exit reasons/codes Sean Christopherson
2022-08-30 23:16 ` [PATCH v5 26/27] KVM: selftests: Add an x86-only test to verify nested exception queueing Sean Christopherson
2022-08-30 23:16 ` [PATCH v5 27/27] KVM: x86: Allow force_emulation_prefix to be written without a reload Sean Christopherson
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