On 24/8/2021 3:37 am, Sean Christopherson wrote:
Override the Processor Trace (PT) interrupt handler for guest mode if and
only if PT is configured for host+guest mode, i.e. is being used
independently by both host and guest. If PT is configured for system
mode, the host fully controls PT and must handle all events.
Fixes: 8479e04e7d6b ("KVM: x86: Inject PMI for KVM guest")
Cc: stable@xxxxxxxxxxxxxxx
Reported-by: Alexander Shishkin <alexander.shishkin@xxxxxxxxxxxxxxx>
Reported-by: Artem Kashkanov <artem.kashkanov@xxxxxxxxx>
Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
---
arch/x86/include/asm/kvm_host.h | 1 +
arch/x86/kvm/pmu.h | 1 +
arch/x86/kvm/vmx/vmx.c | 1 +
arch/x86/kvm/x86.c | 4 +++-
4 files changed, 6 insertions(+), 1 deletion(-)
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 09b256db394a..1ea4943a73d7 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1494,6 +1494,7 @@ struct kvm_x86_init_ops {
int (*disabled_by_bios)(void);
int (*check_processor_compatibility)(void);
int (*hardware_setup)(void);
+ bool (*intel_pt_intr_in_guest)(void);
struct kvm_x86_ops *runtime_ops;
};
diff --git a/arch/x86/kvm/pmu.h b/arch/x86/kvm/pmu.h
index 0e4f2b1fa9fb..b06dbbd7eeeb 100644
--- a/arch/x86/kvm/pmu.h
+++ b/arch/x86/kvm/pmu.h
@@ -41,6 +41,7 @@ struct kvm_pmu_ops {
void (*reset)(struct kvm_vcpu *vcpu);
void (*deliver_pmi)(struct kvm_vcpu *vcpu);
void (*cleanup)(struct kvm_vcpu *vcpu);
+ void (*handle_intel_pt_intr)(void);
};
static inline u64 pmc_bitmask(struct kvm_pmc *pmc)
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index fada1055f325..f19d72136f77 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -7896,6 +7896,7 @@ static struct kvm_x86_init_ops vmx_init_ops __initdata = {
.disabled_by_bios = vmx_disabled_by_bios,
.check_processor_compatibility = vmx_check_processor_compat,
.hardware_setup = hardware_setup,
+ .intel_pt_intr_in_guest = vmx_pt_mode_is_host_guest,
.runtime_ops = &vmx_x86_ops,
};
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index fb6015f97f9e..b5ade47dad9c 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -8305,7 +8305,7 @@ static struct perf_guest_info_callbacks kvm_guest_cbs = {
.is_in_guest = kvm_is_in_guest,
.is_user_mode = kvm_is_user_mode,
.get_guest_ip = kvm_get_guest_ip,
- .handle_intel_pt_intr = kvm_handle_intel_pt_intr,
+ .handle_intel_pt_intr = NULL,
};
#ifdef CONFIG_X86_64
@@ -11061,6 +11061,8 @@ int kvm_arch_hardware_setup(void *opaque)
memcpy(&kvm_x86_ops, ops->runtime_ops, sizeof(kvm_x86_ops));
kvm_ops_static_call_update();
+ if (ops->intel_pt_intr_in_guest && ops->intel_pt_intr_in_guest())
+ kvm_guest_cbs.handle_intel_pt_intr = kvm_handle_intel_pt_intr;
Emm, it's still buggy.
The guest "unknown NMI" from the host Intel PT can still be reproduced
after the following operation:
rmmod kvm_intel
modprobe kvm-intel pt_mode=1 ept=1
rmmod kvm_intel
modprobe kvm-intel pt_mode=1 ept=0
Since the handle_intel_pt_intr is not reset to NULL in kvm_arch_hardware_unsetup(),
and the previous function pointer still exists in the generic KVM data structure.
But I have to say that this fix is much better than the one I proposed [1].
[1] https://lore.kernel.org/lkml/20210514084436.848396-1-like.xu@xxxxxxxxxxxxxxx/
perf_register_guest_info_callbacks(&kvm_guest_cbs);
if (!kvm_cpu_cap_has(X86_FEATURE_XSAVES))
