| Message ID | 20210622172244.3561540-1-seanjc@google.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | KVM: nVMX: Handle split-lock #AC exceptions that happen in L2 | expand |
On 6/23/2021 1:22 AM, Sean Christopherson wrote: > Mark #ACs that won't be reinjected to the guest as wanted by L0 so that > KVM handles split-lock #AC from L2 instead of forwarding the exception to > L1. Split-lock #AC isn't yet virtualized, i.e. L1 will treat it like a > regular #AC and do the wrong thing, e.g. reinject it into L2. > > Fixes: e6f8b6c12f03 ("KVM: VMX: Extend VMXs #AC interceptor to handle split lock #AC in guest") > Cc: Xiaoyao Li <xiaoyao.li@intel.com> > Signed-off-by: Sean Christopherson <seanjc@google.com> > --- > arch/x86/kvm/vmx/nested.c | 3 +++ > arch/x86/kvm/vmx/vmcs.h | 5 +++++ > arch/x86/kvm/vmx/vmx.c | 4 ++-- > arch/x86/kvm/vmx/vmx.h | 1 + > 4 files changed, 11 insertions(+), 2 deletions(-) > > diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c > index 183fd9d62fc5..fa3f50f0a3fa 100644 > --- a/arch/x86/kvm/vmx/nested.c > +++ b/arch/x86/kvm/vmx/nested.c > @@ -5833,6 +5833,9 @@ static bool nested_vmx_l0_wants_exit(struct kvm_vcpu *vcpu, > else if (is_breakpoint(intr_info) && > vcpu->guest_debug & KVM_GUESTDBG_USE_SW_BP) > return true; > + else if (is_alignment_check(intr_info) && > + !vmx_guest_inject_ac(vcpu)) > + return true; Why choose to check in nested_vmx_l0_wants_exit, not in nested_vmx_l1_wants_exit()? > return false; > case EXIT_REASON_EXTERNAL_INTERRUPT: > return true;
On 23/06/21 04:43, Xiaoyao Li wrote: >> >> + else if (is_alignment_check(intr_info) && >> + !vmx_guest_inject_ac(vcpu)) >> + return true; > > Why choose to check in nested_vmx_l0_wants_exit, not in > nested_vmx_l1_wants_exit()? nested_vmx_l0_wants_exit() == true means "this is a vmexit that needs some transformation before being injected into L1". Instead, nested_vmx_l1_wants_exit() == true means "this is an event that should either be processed directly by L0, or cause a vmexit in L1" Typically, nested_vmx_l1_wants_exit() checks the controls in vmcs12, while nested_vmx_l0_wants_exit() returns true unconditionally for most vmexits; for others it checks processor state, or other state set up by userspace with ioctls such as vcpu->guest_debug. In this case it's *L0* that wants that vmexit, in order to either disable split-lock detection or inject a SIGBUS, so nested_vmx_l0_wants_exit() is the right one to test. Paolo
On 22/06/21 19:22, Sean Christopherson wrote: > Mark #ACs that won't be reinjected to the guest as wanted by L0 so that > KVM handles split-lock #AC from L2 instead of forwarding the exception to > L1. Split-lock #AC isn't yet virtualized, i.e. L1 will treat it like a > regular #AC and do the wrong thing, e.g. reinject it into L2. > > Fixes: e6f8b6c12f03 ("KVM: VMX: Extend VMXs #AC interceptor to handle split lock #AC in guest") > Cc: Xiaoyao Li <xiaoyao.li@intel.com> > Signed-off-by: Sean Christopherson <seanjc@google.com> > --- > arch/x86/kvm/vmx/nested.c | 3 +++ > arch/x86/kvm/vmx/vmcs.h | 5 +++++ > arch/x86/kvm/vmx/vmx.c | 4 ++-- > arch/x86/kvm/vmx/vmx.h | 1 + > 4 files changed, 11 insertions(+), 2 deletions(-) > > diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c > index 183fd9d62fc5..fa3f50f0a3fa 100644 > --- a/arch/x86/kvm/vmx/nested.c > +++ b/arch/x86/kvm/vmx/nested.c > @@ -5833,6 +5833,9 @@ static bool nested_vmx_l0_wants_exit(struct kvm_vcpu *vcpu, > else if (is_breakpoint(intr_info) && > vcpu->guest_debug & KVM_GUESTDBG_USE_SW_BP) > return true; > + else if (is_alignment_check(intr_info) && > + !vmx_guest_inject_ac(vcpu)) > + return true; > return false; > case EXIT_REASON_EXTERNAL_INTERRUPT: > return true; > diff --git a/arch/x86/kvm/vmx/vmcs.h b/arch/x86/kvm/vmx/vmcs.h > index de3b04d4b587..4b9957e2bf5b 100644 > --- a/arch/x86/kvm/vmx/vmcs.h > +++ b/arch/x86/kvm/vmx/vmcs.h > @@ -117,6 +117,11 @@ static inline bool is_gp_fault(u32 intr_info) > return is_exception_n(intr_info, GP_VECTOR); > } > > +static inline bool is_alignment_check(u32 intr_info) > +{ > + return is_exception_n(intr_info, AC_VECTOR); > +} > + > static inline bool is_machine_check(u32 intr_info) > { > return is_exception_n(intr_info, MC_VECTOR); > diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c > index ab6f682645d7..46d9ce39249d 100644 > --- a/arch/x86/kvm/vmx/vmx.c > +++ b/arch/x86/kvm/vmx/vmx.c > @@ -4743,7 +4743,7 @@ static int handle_machine_check(struct kvm_vcpu *vcpu) > * - Guest has #AC detection enabled in CR0 > * - Guest EFLAGS has AC bit set > */ > -static inline bool guest_inject_ac(struct kvm_vcpu *vcpu) > +bool vmx_guest_inject_ac(struct kvm_vcpu *vcpu) > { > if (!boot_cpu_has(X86_FEATURE_SPLIT_LOCK_DETECT)) > return true; > @@ -4851,7 +4851,7 @@ static int handle_exception_nmi(struct kvm_vcpu *vcpu) > kvm_run->debug.arch.exception = ex_no; > break; > case AC_VECTOR: > - if (guest_inject_ac(vcpu)) { > + if (vmx_guest_inject_ac(vcpu)) { > kvm_queue_exception_e(vcpu, AC_VECTOR, error_code); > return 1; > } > diff --git a/arch/x86/kvm/vmx/vmx.h b/arch/x86/kvm/vmx/vmx.h > index 5740f8e2aa23..3979a947933a 100644 > --- a/arch/x86/kvm/vmx/vmx.h > +++ b/arch/x86/kvm/vmx/vmx.h > @@ -376,6 +376,7 @@ void vmx_get_segment(struct kvm_vcpu *vcpu, struct kvm_segment *var, int seg); > void vmx_set_segment(struct kvm_vcpu *vcpu, struct kvm_segment *var, int seg); > u64 construct_eptp(struct kvm_vcpu *vcpu, hpa_t root_hpa, int root_level); > > +bool vmx_guest_inject_ac(struct kvm_vcpu *vcpu); > void vmx_update_exception_bitmap(struct kvm_vcpu *vcpu); > void vmx_update_msr_bitmap(struct kvm_vcpu *vcpu); > bool vmx_nmi_blocked(struct kvm_vcpu *vcpu); > Queued with Cc to stable, thanks. Paolo
diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c index 183fd9d62fc5..fa3f50f0a3fa 100644 --- a/arch/x86/kvm/vmx/nested.c +++ b/arch/x86/kvm/vmx/nested.c @@ -5833,6 +5833,9 @@ static bool nested_vmx_l0_wants_exit(struct kvm_vcpu *vcpu, else if (is_breakpoint(intr_info) && vcpu->guest_debug & KVM_GUESTDBG_USE_SW_BP) return true; + else if (is_alignment_check(intr_info) && + !vmx_guest_inject_ac(vcpu)) + return true; return false; case EXIT_REASON_EXTERNAL_INTERRUPT: return true; diff --git a/arch/x86/kvm/vmx/vmcs.h b/arch/x86/kvm/vmx/vmcs.h index de3b04d4b587..4b9957e2bf5b 100644 --- a/arch/x86/kvm/vmx/vmcs.h +++ b/arch/x86/kvm/vmx/vmcs.h @@ -117,6 +117,11 @@ static inline bool is_gp_fault(u32 intr_info) return is_exception_n(intr_info, GP_VECTOR); } +static inline bool is_alignment_check(u32 intr_info) +{ + return is_exception_n(intr_info, AC_VECTOR); +} + static inline bool is_machine_check(u32 intr_info) { return is_exception_n(intr_info, MC_VECTOR); diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index ab6f682645d7..46d9ce39249d 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -4743,7 +4743,7 @@ static int handle_machine_check(struct kvm_vcpu *vcpu) * - Guest has #AC detection enabled in CR0 * - Guest EFLAGS has AC bit set */ -static inline bool guest_inject_ac(struct kvm_vcpu *vcpu) +bool vmx_guest_inject_ac(struct kvm_vcpu *vcpu) { if (!boot_cpu_has(X86_FEATURE_SPLIT_LOCK_DETECT)) return true; @@ -4851,7 +4851,7 @@ static int handle_exception_nmi(struct kvm_vcpu *vcpu) kvm_run->debug.arch.exception = ex_no; break; case AC_VECTOR: - if (guest_inject_ac(vcpu)) { + if (vmx_guest_inject_ac(vcpu)) { kvm_queue_exception_e(vcpu, AC_VECTOR, error_code); return 1; } diff --git a/arch/x86/kvm/vmx/vmx.h b/arch/x86/kvm/vmx/vmx.h index 5740f8e2aa23..3979a947933a 100644 --- a/arch/x86/kvm/vmx/vmx.h +++ b/arch/x86/kvm/vmx/vmx.h @@ -376,6 +376,7 @@ void vmx_get_segment(struct kvm_vcpu *vcpu, struct kvm_segment *var, int seg); void vmx_set_segment(struct kvm_vcpu *vcpu, struct kvm_segment *var, int seg); u64 construct_eptp(struct kvm_vcpu *vcpu, hpa_t root_hpa, int root_level); +bool vmx_guest_inject_ac(struct kvm_vcpu *vcpu); void vmx_update_exception_bitmap(struct kvm_vcpu *vcpu); void vmx_update_msr_bitmap(struct kvm_vcpu *vcpu); bool vmx_nmi_blocked(struct kvm_vcpu *vcpu);
Mark #ACs that won't be reinjected to the guest as wanted by L0 so that KVM handles split-lock #AC from L2 instead of forwarding the exception to L1. Split-lock #AC isn't yet virtualized, i.e. L1 will treat it like a regular #AC and do the wrong thing, e.g. reinject it into L2. Fixes: e6f8b6c12f03 ("KVM: VMX: Extend VMXs #AC interceptor to handle split lock #AC in guest") Cc: Xiaoyao Li <xiaoyao.li@intel.com> Signed-off-by: Sean Christopherson <seanjc@google.com> --- arch/x86/kvm/vmx/nested.c | 3 +++ arch/x86/kvm/vmx/vmcs.h | 5 +++++ arch/x86/kvm/vmx/vmx.c | 4 ++-- arch/x86/kvm/vmx/vmx.h | 1 + 4 files changed, 11 insertions(+), 2 deletions(-)