| Message ID | 20181109150711.45864-2-mark.rutland@arm.com |
|---|---|
| State | New |
| Headers | show |
| Series | kvm/arm: make singlestep behaviour consistent | expand |
Mark Rutland <mark.rutland@arm.com> writes: > When we emulate an MMIO instruction, we advance the CPU state within > decode_hsr(), before emulating the instruction effects. > > Having this logic in decode_hsr() is opaque, and advancing the state > before emulation is problematic. It gets in the way of applying > consistent single-step logic, and it prevents us from being able to fail > an MMIO instruction with a synchronous exception. > > Clean this up by only advancing the CPU state *after* the effects of the > instruction are emulated. > > Signed-off-by: Mark Rutland <mark.rutland@arm.com> > Cc: Alex Bennée <alex.bennee@linaro.org> > Cc: Christoffer Dall <christoffer.dall@arm.com> > Cc: Marc Zyngier <marc.zyngier@arm.com> > Cc: Peter Maydell <peter.maydell@linaro.org> Reviewed-by: Alex Bennée <alex.bennee@linaro.org> > --- > virt/kvm/arm/mmio.c | 11 ++++++----- > 1 file changed, 6 insertions(+), 5 deletions(-) > > diff --git a/virt/kvm/arm/mmio.c b/virt/kvm/arm/mmio.c > index dac7ceb1a677..08443a15e6be 100644 > --- a/virt/kvm/arm/mmio.c > +++ b/virt/kvm/arm/mmio.c > @@ -117,6 +117,12 @@ int kvm_handle_mmio_return(struct kvm_vcpu *vcpu, struct kvm_run *run) > vcpu_set_reg(vcpu, vcpu->arch.mmio_decode.rt, data); > } > > + /* > + * The MMIO instruction is emulated and should not be re-executed > + * in the guest. > + */ > + kvm_skip_instr(vcpu, kvm_vcpu_trap_il_is32bit(vcpu)); > + > return 0; > } > > @@ -144,11 +150,6 @@ static int decode_hsr(struct kvm_vcpu *vcpu, bool *is_write, int *len) > vcpu->arch.mmio_decode.sign_extend = sign_extend; > vcpu->arch.mmio_decode.rt = rt; > > - /* > - * The MMIO instruction is emulated and should not be re-executed > - * in the guest. > - */ > - kvm_skip_instr(vcpu, kvm_vcpu_trap_il_is32bit(vcpu)); > return 0; > } -- Alex Bennée
On Fri, Nov 09, 2018 at 03:07:10PM +0000, Mark Rutland wrote: > When we emulate an MMIO instruction, we advance the CPU state within > decode_hsr(), before emulating the instruction effects. > > Having this logic in decode_hsr() is opaque, and advancing the state > before emulation is problematic. It gets in the way of applying > consistent single-step logic, and it prevents us from being able to fail > an MMIO instruction with a synchronous exception. > > Clean this up by only advancing the CPU state *after* the effects of the > instruction are emulated. > > Signed-off-by: Mark Rutland <mark.rutland@arm.com> > Cc: Alex Bennée <alex.bennee@linaro.org> > Cc: Christoffer Dall <christoffer.dall@arm.com> > Cc: Marc Zyngier <marc.zyngier@arm.com> > Cc: Peter Maydell <peter.maydell@linaro.org> > --- > virt/kvm/arm/mmio.c | 11 ++++++----- > 1 file changed, 6 insertions(+), 5 deletions(-) > > diff --git a/virt/kvm/arm/mmio.c b/virt/kvm/arm/mmio.c > index dac7ceb1a677..08443a15e6be 100644 > --- a/virt/kvm/arm/mmio.c > +++ b/virt/kvm/arm/mmio.c > @@ -117,6 +117,12 @@ int kvm_handle_mmio_return(struct kvm_vcpu *vcpu, struct kvm_run *run) > vcpu_set_reg(vcpu, vcpu->arch.mmio_decode.rt, data); > } > > + /* > + * The MMIO instruction is emulated and should not be re-executed > + * in the guest. > + */ > + kvm_skip_instr(vcpu, kvm_vcpu_trap_il_is32bit(vcpu)); > + > return 0; > } > > @@ -144,11 +150,6 @@ static int decode_hsr(struct kvm_vcpu *vcpu, bool *is_write, int *len) > vcpu->arch.mmio_decode.sign_extend = sign_extend; > vcpu->arch.mmio_decode.rt = rt; > > - /* > - * The MMIO instruction is emulated and should not be re-executed > - * in the guest. > - */ > - kvm_skip_instr(vcpu, kvm_vcpu_trap_il_is32bit(vcpu)); > return 0; > } > > -- > 2.11.0 > Reviewed-by: Christoffer Dall <christoffer.dall@arm.com>
diff --git a/virt/kvm/arm/mmio.c b/virt/kvm/arm/mmio.c index dac7ceb1a677..08443a15e6be 100644 --- a/virt/kvm/arm/mmio.c +++ b/virt/kvm/arm/mmio.c @@ -117,6 +117,12 @@ int kvm_handle_mmio_return(struct kvm_vcpu *vcpu, struct kvm_run *run) vcpu_set_reg(vcpu, vcpu->arch.mmio_decode.rt, data); } + /* + * The MMIO instruction is emulated and should not be re-executed + * in the guest. + */ + kvm_skip_instr(vcpu, kvm_vcpu_trap_il_is32bit(vcpu)); + return 0; } @@ -144,11 +150,6 @@ static int decode_hsr(struct kvm_vcpu *vcpu, bool *is_write, int *len) vcpu->arch.mmio_decode.sign_extend = sign_extend; vcpu->arch.mmio_decode.rt = rt; - /* - * The MMIO instruction is emulated and should not be re-executed - * in the guest. - */ - kvm_skip_instr(vcpu, kvm_vcpu_trap_il_is32bit(vcpu)); return 0; }
When we emulate an MMIO instruction, we advance the CPU state within decode_hsr(), before emulating the instruction effects. Having this logic in decode_hsr() is opaque, and advancing the state before emulation is problematic. It gets in the way of applying consistent single-step logic, and it prevents us from being able to fail an MMIO instruction with a synchronous exception. Clean this up by only advancing the CPU state *after* the effects of the instruction are emulated. Signed-off-by: Mark Rutland <mark.rutland@arm.com> Cc: Alex Bennée <alex.bennee@linaro.org> Cc: Christoffer Dall <christoffer.dall@arm.com> Cc: Marc Zyngier <marc.zyngier@arm.com> Cc: Peter Maydell <peter.maydell@linaro.org> --- virt/kvm/arm/mmio.c | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-)