| Message ID | 1509977710-29704-1-git-send-email-liran.alon@oracle.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 06/11/2017 15:15, Liran Alon wrote: > When running L2, #UD should be intercepted by L1 or just forwarded > directly to L2. It should not reach L0 x86 emulator. > Therefore, set intercept for #UD only based on L1 exception-bitmap. > > Also add WARN_ON_ONCE() on L0 #UD intercept handlers to make sure > it is never reached while running L2. > > This improves commit ae1f57670703 ("KVM: nVMX: Do not emulate #UD while > in guest mode") by removing an unnecessary exit from L2 to L0 on #UD > when L1 doesn't intercept it. > > In addition, SVM L0 #UD intercept handler doesn't handle correctly the > case it is raised from L2. In this case, it should forward the #UD to > guest instead of x86 emulator. As done in VMX #UD intercept handler. > This commit fixes this issue as-well. > > Signed-off-by: Liran Alon <liran.alon@oracle.com> > Reviewed-by: Nikita Leshenko <nikita.leshchenko@oracle.com> > Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> > Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> > --- > arch/x86/kvm/svm.c | 9 ++++++++- > arch/x86/kvm/vmx.c | 9 ++++----- > 2 files changed, 12 insertions(+), 6 deletions(-) > > diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c > index 0e68f0b3cbf7..e49d44afbe9a 100644 > --- a/arch/x86/kvm/svm.c > +++ b/arch/x86/kvm/svm.c > @@ -361,6 +361,7 @@ static void recalc_intercepts(struct vcpu_svm *svm) > { > struct vmcb_control_area *c, *h; > struct nested_state *g; > + u32 h_intercept_exceptions; > > mark_dirty(svm->vmcb, VMCB_INTERCEPTS); > > @@ -371,9 +372,14 @@ static void recalc_intercepts(struct vcpu_svm *svm) > h = &svm->nested.hsave->control; > g = &svm->nested; > > + /* No need to intercept #UD if L1 doesn't intercept it */ > + h_intercept_exceptions = > + h->intercept_exceptions & ~(1U << UD_VECTOR); > + > c->intercept_cr = h->intercept_cr | g->intercept_cr; > c->intercept_dr = h->intercept_dr | g->intercept_dr; > - c->intercept_exceptions = h->intercept_exceptions | g->intercept_exceptions; > + c->intercept_exceptions = > + h_intercept_exceptions | g->intercept_exceptions; > c->intercept = h->intercept | g->intercept; > } > > @@ -2188,6 +2194,7 @@ static int ud_interception(struct vcpu_svm *svm) > { > int er; > > + WARN_ON_ONCE(is_guest_mode(&svm->vcpu)); > er = emulate_instruction(&svm->vcpu, EMULTYPE_TRAP_UD); > if (er != EMULATE_DONE) > kvm_queue_exception(&svm->vcpu, UD_VECTOR); > diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c > index 95a01609d7ee..dfa856d31b17 100644 > --- a/arch/x86/kvm/vmx.c > +++ b/arch/x86/kvm/vmx.c > @@ -1878,7 +1878,7 @@ static void update_exception_bitmap(struct kvm_vcpu *vcpu) > { > u32 eb; > > - eb = (1u << PF_VECTOR) | (1u << UD_VECTOR) | (1u << MC_VECTOR) | > + eb = (1u << PF_VECTOR) | (1u << MC_VECTOR) | > (1u << DB_VECTOR) | (1u << AC_VECTOR); > if ((vcpu->guest_debug & > (KVM_GUESTDBG_ENABLE | KVM_GUESTDBG_USE_SW_BP)) == > @@ -1896,6 +1896,8 @@ static void update_exception_bitmap(struct kvm_vcpu *vcpu) > */ > if (is_guest_mode(vcpu)) > eb |= get_vmcs12(vcpu)->exception_bitmap; > + else > + eb |= 1u << UD_VECTOR; > > vmcs_write32(EXCEPTION_BITMAP, eb); > } > @@ -5881,10 +5883,7 @@ static int handle_exception(struct kvm_vcpu *vcpu) > return 1; /* already handled by vmx_vcpu_run() */ > > if (is_invalid_opcode(intr_info)) { > - if (is_guest_mode(vcpu)) { > - kvm_queue_exception(vcpu, UD_VECTOR); > - return 1; > - } > + WARN_ON_ONCE(is_guest_mode(vcpu)); > er = emulate_instruction(vcpu, EMULTYPE_TRAP_UD); > if (er != EMULATE_DONE) > kvm_queue_exception(vcpu, UD_VECTOR); > Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
2017-11-06 22:15 GMT+08:00 Liran Alon <liran.alon@oracle.com>: > When running L2, #UD should be intercepted by L1 or just forwarded > directly to L2. It should not reach L0 x86 emulator. > Therefore, set intercept for #UD only based on L1 exception-bitmap. > > Also add WARN_ON_ONCE() on L0 #UD intercept handlers to make sure > it is never reached while running L2. > > This improves commit ae1f57670703 ("KVM: nVMX: Do not emulate #UD while > in guest mode") by removing an unnecessary exit from L2 to L0 on #UD > when L1 doesn't intercept it. > > In addition, SVM L0 #UD intercept handler doesn't handle correctly the > case it is raised from L2. In this case, it should forward the #UD to > guest instead of x86 emulator. As done in VMX #UD intercept handler. > This commit fixes this issue as-well. > > Signed-off-by: Liran Alon <liran.alon@oracle.com> > Reviewed-by: Nikita Leshenko <nikita.leshchenko@oracle.com> > Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> > Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Reviewed-by: Wanpeng Li <wanpeng.li@hotmail.com> > --- > arch/x86/kvm/svm.c | 9 ++++++++- > arch/x86/kvm/vmx.c | 9 ++++----- > 2 files changed, 12 insertions(+), 6 deletions(-) > > diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c > index 0e68f0b3cbf7..e49d44afbe9a 100644 > --- a/arch/x86/kvm/svm.c > +++ b/arch/x86/kvm/svm.c > @@ -361,6 +361,7 @@ static void recalc_intercepts(struct vcpu_svm *svm) > { > struct vmcb_control_area *c, *h; > struct nested_state *g; > + u32 h_intercept_exceptions; > > mark_dirty(svm->vmcb, VMCB_INTERCEPTS); > > @@ -371,9 +372,14 @@ static void recalc_intercepts(struct vcpu_svm *svm) > h = &svm->nested.hsave->control; > g = &svm->nested; > > + /* No need to intercept #UD if L1 doesn't intercept it */ > + h_intercept_exceptions = > + h->intercept_exceptions & ~(1U << UD_VECTOR); > + > c->intercept_cr = h->intercept_cr | g->intercept_cr; > c->intercept_dr = h->intercept_dr | g->intercept_dr; > - c->intercept_exceptions = h->intercept_exceptions | g->intercept_exceptions; > + c->intercept_exceptions = > + h_intercept_exceptions | g->intercept_exceptions; > c->intercept = h->intercept | g->intercept; > } > > @@ -2188,6 +2194,7 @@ static int ud_interception(struct vcpu_svm *svm) > { > int er; > > + WARN_ON_ONCE(is_guest_mode(&svm->vcpu)); > er = emulate_instruction(&svm->vcpu, EMULTYPE_TRAP_UD); > if (er != EMULATE_DONE) > kvm_queue_exception(&svm->vcpu, UD_VECTOR); > diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c > index 95a01609d7ee..dfa856d31b17 100644 > --- a/arch/x86/kvm/vmx.c > +++ b/arch/x86/kvm/vmx.c > @@ -1878,7 +1878,7 @@ static void update_exception_bitmap(struct kvm_vcpu *vcpu) > { > u32 eb; > > - eb = (1u << PF_VECTOR) | (1u << UD_VECTOR) | (1u << MC_VECTOR) | > + eb = (1u << PF_VECTOR) | (1u << MC_VECTOR) | > (1u << DB_VECTOR) | (1u << AC_VECTOR); > if ((vcpu->guest_debug & > (KVM_GUESTDBG_ENABLE | KVM_GUESTDBG_USE_SW_BP)) == > @@ -1896,6 +1896,8 @@ static void update_exception_bitmap(struct kvm_vcpu *vcpu) > */ > if (is_guest_mode(vcpu)) > eb |= get_vmcs12(vcpu)->exception_bitmap; > + else > + eb |= 1u << UD_VECTOR; > > vmcs_write32(EXCEPTION_BITMAP, eb); > } > @@ -5881,10 +5883,7 @@ static int handle_exception(struct kvm_vcpu *vcpu) > return 1; /* already handled by vmx_vcpu_run() */ > > if (is_invalid_opcode(intr_info)) { > - if (is_guest_mode(vcpu)) { > - kvm_queue_exception(vcpu, UD_VECTOR); > - return 1; > - } > + WARN_ON_ONCE(is_guest_mode(vcpu)); > er = emulate_instruction(vcpu, EMULTYPE_TRAP_UD); > if (er != EMULATE_DONE) > kvm_queue_exception(vcpu, UD_VECTOR); > -- > 1.9.1 >
2017-11-06 16:15+0200, Liran Alon: > When running L2, #UD should be intercepted by L1 or just forwarded > directly to L2. It should not reach L0 x86 emulator. > Therefore, set intercept for #UD only based on L1 exception-bitmap. > > Also add WARN_ON_ONCE() on L0 #UD intercept handlers to make sure > it is never reached while running L2. > > This improves commit ae1f57670703 ("KVM: nVMX: Do not emulate #UD while > in guest mode") by removing an unnecessary exit from L2 to L0 on #UD > when L1 doesn't intercept it. > > In addition, SVM L0 #UD intercept handler doesn't handle correctly the > case it is raised from L2. In this case, it should forward the #UD to > guest instead of x86 emulator. As done in VMX #UD intercept handler. > This commit fixes this issue as-well. > > Signed-off-by: Liran Alon <liran.alon@oracle.com> > Reviewed-by: Nikita Leshenko <nikita.leshchenko@oracle.com> > Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> > Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> > --- Applied, thanks.
How does this change interact with commit 84cffe499b94 ("kvm: Emulate MOVBE")?
If the hardware doesn't support MOVBE, but L0 sets CPUID.01H:ECX.MOVBE
in L1's emulated CPUID information, then L1 is likely to pass that
CPUID bit through to L2. L2 will expect MOVBE to work, but if L1
doesn't intercept #UD, then any MOVBE instruction executed in L2 will
raise #UD, and the exception will be delivered in L2.
On Fri, Nov 10, 2017 at 1:37 PM, Radim Krčmář <rkrcmar@redhat.com> wrote:
> 2017-11-06 16:15+0200, Liran Alon:
>> When running L2, #UD should be intercepted by L1 or just forwarded
>> directly to L2. It should not reach L0 x86 emulator.
>> Therefore, set intercept for #UD only based on L1 exception-bitmap.
>>
>> Also add WARN_ON_ONCE() on L0 #UD intercept handlers to make sure
>> it is never reached while running L2.
>>
>> This improves commit ae1f57670703 ("KVM: nVMX: Do not emulate #UD while
>> in guest mode") by removing an unnecessary exit from L2 to L0 on #UD
>> when L1 doesn't intercept it.
>>
>> In addition, SVM L0 #UD intercept handler doesn't handle correctly the
>> case it is raised from L2. In this case, it should forward the #UD to
>> guest instead of x86 emulator. As done in VMX #UD intercept handler.
>> This commit fixes this issue as-well.
>>
>> Signed-off-by: Liran Alon <liran.alon@oracle.com>
>> Reviewed-by: Nikita Leshenko <nikita.leshchenko@oracle.com>
>> Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
>> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
>> ---
>
> Applied, thanks.
In fact, even if L1 does intercept #UD, it may not be prepared to emulate MOVBE. On Fri, Dec 1, 2017 at 3:00 PM, Jim Mattson <jmattson@google.com> wrote: > How does this change interact with commit 84cffe499b94 ("kvm: Emulate MOVBE")? > > If the hardware doesn't support MOVBE, but L0 sets CPUID.01H:ECX.MOVBE > in L1's emulated CPUID information, then L1 is likely to pass that > CPUID bit through to L2. L2 will expect MOVBE to work, but if L1 > doesn't intercept #UD, then any MOVBE instruction executed in L2 will > raise #UD, and the exception will be delivered in L2. > > > On Fri, Nov 10, 2017 at 1:37 PM, Radim Krčmář <rkrcmar@redhat.com> wrote: >> 2017-11-06 16:15+0200, Liran Alon: >>> When running L2, #UD should be intercepted by L1 or just forwarded >>> directly to L2. It should not reach L0 x86 emulator. >>> Therefore, set intercept for #UD only based on L1 exception-bitmap. >>> >>> Also add WARN_ON_ONCE() on L0 #UD intercept handlers to make sure >>> it is never reached while running L2. >>> >>> This improves commit ae1f57670703 ("KVM: nVMX: Do not emulate #UD while >>> in guest mode") by removing an unnecessary exit from L2 to L0 on #UD >>> when L1 doesn't intercept it. >>> >>> In addition, SVM L0 #UD intercept handler doesn't handle correctly the >>> case it is raised from L2. In this case, it should forward the #UD to >>> guest instead of x86 emulator. As done in VMX #UD intercept handler. >>> This commit fixes this issue as-well. >>> >>> Signed-off-by: Liran Alon <liran.alon@oracle.com> >>> Reviewed-by: Nikita Leshenko <nikita.leshchenko@oracle.com> >>> Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> >>> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> >>> --- >> >> Applied, thanks.
On 02/12/17 01:00, Jim Mattson wrote: > How does this change interact with commit 84cffe499b94 ("kvm: Emulate MOVBE")? > > If the hardware doesn't support MOVBE, but L0 sets CPUID.01H:ECX.MOVBE > in L1's emulated CPUID information, then L1 is likely to pass that > CPUID bit through to L2. L2 will expect MOVBE to work, but if L1 > doesn't intercept #UD, then any MOVBE instruction executed in L2 will > raise #UD, and the exception will be delivered in L2. > Nice catch. When I considered the functionality of the original commit which I attempted to fix (commit ae1f57670703 ("KVM: nVMX: Do not emulate #UD while in guest mode")), my patch made sense as a more complete and better fix. However, both my patch and the original patch don't seem to consider the issue you present here. I completely agree. Maybe it was better just reverting my patch and commit ae1f57670703. I think the attempt of that patch was to make L0 not simulate behaviour it simulates for L1 in L2 as-well. but after reading your reply, I think that it is a desired behaviour... -Liran > > On Fri, Nov 10, 2017 at 1:37 PM, Radim Krčmář <rkrcmar@redhat.com> wrote: >> 2017-11-06 16:15+0200, Liran Alon: >>> When running L2, #UD should be intercepted by L1 or just forwarded >>> directly to L2. It should not reach L0 x86 emulator. >>> Therefore, set intercept for #UD only based on L1 exception-bitmap. >>> >>> Also add WARN_ON_ONCE() on L0 #UD intercept handlers to make sure >>> it is never reached while running L2. >>> >>> This improves commit ae1f57670703 ("KVM: nVMX: Do not emulate #UD while >>> in guest mode") by removing an unnecessary exit from L2 to L0 on #UD >>> when L1 doesn't intercept it. >>> >>> In addition, SVM L0 #UD intercept handler doesn't handle correctly the >>> case it is raised from L2. In this case, it should forward the #UD to >>> guest instead of x86 emulator. As done in VMX #UD intercept handler. >>> This commit fixes this issue as-well. >>> >>> Signed-off-by: Liran Alon <liran.alon@oracle.com> >>> Reviewed-by: Nikita Leshenko <nikita.leshchenko@oracle.com> >>> Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> >>> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> >>> --- >> >> Applied, thanks.
Liran, Are you planning to submit reverts for ae1f57670703 and ac9b305caa0d? On Fri, Dec 1, 2017 at 4:27 PM, Liran Alon <LIRAN.ALON@oracle.com> wrote: > > > On 02/12/17 01:00, Jim Mattson wrote: >> >> How does this change interact with commit 84cffe499b94 ("kvm: Emulate >> MOVBE")? >> >> If the hardware doesn't support MOVBE, but L0 sets CPUID.01H:ECX.MOVBE >> in L1's emulated CPUID information, then L1 is likely to pass that >> CPUID bit through to L2. L2 will expect MOVBE to work, but if L1 >> doesn't intercept #UD, then any MOVBE instruction executed in L2 will >> raise #UD, and the exception will be delivered in L2. >> > > Nice catch. > > When I considered the functionality of the original commit which I attempted > to fix (commit ae1f57670703 ("KVM: nVMX: Do not emulate #UD while in guest > mode")), my patch made sense as a more complete and better fix. > > However, both my patch and the original patch don't seem to consider the > issue you present here. I completely agree. > > Maybe it was better just reverting my patch and commit ae1f57670703. I think > the attempt of that patch was to make L0 not simulate behaviour it simulates > for L1 in L2 as-well. but after reading your reply, I think that it is a > desired behaviour... > > -Liran > > >> >> On Fri, Nov 10, 2017 at 1:37 PM, Radim Krčmář <rkrcmar@redhat.com> wrote: >>> >>> 2017-11-06 16:15+0200, Liran Alon: >>>> >>>> When running L2, #UD should be intercepted by L1 or just forwarded >>>> directly to L2. It should not reach L0 x86 emulator. >>>> Therefore, set intercept for #UD only based on L1 exception-bitmap. >>>> >>>> Also add WARN_ON_ONCE() on L0 #UD intercept handlers to make sure >>>> it is never reached while running L2. >>>> >>>> This improves commit ae1f57670703 ("KVM: nVMX: Do not emulate #UD while >>>> in guest mode") by removing an unnecessary exit from L2 to L0 on #UD >>>> when L1 doesn't intercept it. >>>> >>>> In addition, SVM L0 #UD intercept handler doesn't handle correctly the >>>> case it is raised from L2. In this case, it should forward the #UD to >>>> guest instead of x86 emulator. As done in VMX #UD intercept handler. >>>> This commit fixes this issue as-well. >>>> >>>> Signed-off-by: Liran Alon <liran.alon@oracle.com> >>>> Reviewed-by: Nikita Leshenko <nikita.leshchenko@oracle.com> >>>> Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> >>>> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> >>>> --- >>> >>> >>> Applied, thanks.
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c index 0e68f0b3cbf7..e49d44afbe9a 100644 --- a/arch/x86/kvm/svm.c +++ b/arch/x86/kvm/svm.c @@ -361,6 +361,7 @@ static void recalc_intercepts(struct vcpu_svm *svm) { struct vmcb_control_area *c, *h; struct nested_state *g; + u32 h_intercept_exceptions; mark_dirty(svm->vmcb, VMCB_INTERCEPTS); @@ -371,9 +372,14 @@ static void recalc_intercepts(struct vcpu_svm *svm) h = &svm->nested.hsave->control; g = &svm->nested; + /* No need to intercept #UD if L1 doesn't intercept it */ + h_intercept_exceptions = + h->intercept_exceptions & ~(1U << UD_VECTOR); + c->intercept_cr = h->intercept_cr | g->intercept_cr; c->intercept_dr = h->intercept_dr | g->intercept_dr; - c->intercept_exceptions = h->intercept_exceptions | g->intercept_exceptions; + c->intercept_exceptions = + h_intercept_exceptions | g->intercept_exceptions; c->intercept = h->intercept | g->intercept; } @@ -2188,6 +2194,7 @@ static int ud_interception(struct vcpu_svm *svm) { int er; + WARN_ON_ONCE(is_guest_mode(&svm->vcpu)); er = emulate_instruction(&svm->vcpu, EMULTYPE_TRAP_UD); if (er != EMULATE_DONE) kvm_queue_exception(&svm->vcpu, UD_VECTOR); diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c index 95a01609d7ee..dfa856d31b17 100644 --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -1878,7 +1878,7 @@ static void update_exception_bitmap(struct kvm_vcpu *vcpu) { u32 eb; - eb = (1u << PF_VECTOR) | (1u << UD_VECTOR) | (1u << MC_VECTOR) | + eb = (1u << PF_VECTOR) | (1u << MC_VECTOR) | (1u << DB_VECTOR) | (1u << AC_VECTOR); if ((vcpu->guest_debug & (KVM_GUESTDBG_ENABLE | KVM_GUESTDBG_USE_SW_BP)) == @@ -1896,6 +1896,8 @@ static void update_exception_bitmap(struct kvm_vcpu *vcpu) */ if (is_guest_mode(vcpu)) eb |= get_vmcs12(vcpu)->exception_bitmap; + else + eb |= 1u << UD_VECTOR; vmcs_write32(EXCEPTION_BITMAP, eb); } @@ -5881,10 +5883,7 @@ static int handle_exception(struct kvm_vcpu *vcpu) return 1; /* already handled by vmx_vcpu_run() */ if (is_invalid_opcode(intr_info)) { - if (is_guest_mode(vcpu)) { - kvm_queue_exception(vcpu, UD_VECTOR); - return 1; - } + WARN_ON_ONCE(is_guest_mode(vcpu)); er = emulate_instruction(vcpu, EMULTYPE_TRAP_UD); if (er != EMULATE_DONE) kvm_queue_exception(vcpu, UD_VECTOR);
When running L2, #UD should be intercepted by L1 or just forwarded directly to L2. It should not reach L0 x86 emulator. Therefore, set intercept for #UD only based on L1 exception-bitmap. Also add WARN_ON_ONCE() on L0 #UD intercept handlers to make sure it is never reached while running L2. This improves commit ae1f57670703 ("KVM: nVMX: Do not emulate #UD while in guest mode") by removing an unnecessary exit from L2 to L0 on #UD when L1 doesn't intercept it. In addition, SVM L0 #UD intercept handler doesn't handle correctly the case it is raised from L2. In this case, it should forward the #UD to guest instead of x86 emulator. As done in VMX #UD intercept handler. This commit fixes this issue as-well. Signed-off-by: Liran Alon <liran.alon@oracle.com> Reviewed-by: Nikita Leshenko <nikita.leshchenko@oracle.com> Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> --- arch/x86/kvm/svm.c | 9 ++++++++- arch/x86/kvm/vmx.c | 9 ++++----- 2 files changed, 12 insertions(+), 6 deletions(-)