| Message ID | 20160329123308.GC4126@cbox (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 29/03/16 13:33, Christoffer Dall wrote: > On Fri, Mar 25, 2016 at 02:04:24AM +0000, Andre Przywara wrote: >> When the kernel was handling a guest MMIO access internally, we need >> to copy the emulation result into the run->mmio structure in order >> for the kvm_handle_mmio_return() function to pick it up and inject >> the result back into the guest. >> Currently the only user of kvm_io_bus for ARM is the VGIC, which did >> this copying itself, so this was not causing issues so far. >> But with upcoming kvm_io_bus users we need to do the copying here. >> >> Signed-off-by: Andre Przywara <andre.przywara@arm.com> >> --- >> arch/arm/kvm/mmio.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/arch/arm/kvm/mmio.c b/arch/arm/kvm/mmio.c >> index 0f6600f..d5c2727 100644 >> --- a/arch/arm/kvm/mmio.c >> +++ b/arch/arm/kvm/mmio.c >> @@ -206,7 +206,7 @@ int io_mem_abort(struct kvm_vcpu *vcpu, struct kvm_run *run, >> run->mmio.is_write = is_write; >> run->mmio.phys_addr = fault_ipa; >> run->mmio.len = len; >> - if (is_write) >> + if (is_write || !ret) >> memcpy(run->mmio.data, data_buf, len); > > I had a really hard time understanding this, how about this instead: Admittedly this is the shortest possible fix. I also had a rework closer to your version, which also avoided copying the arguments in some cases, but I thought a smaller diff would be more suitable, since this is actually a fix. Shall I add a comment here or post my version of the fix instead? Cheers, Andre. > diff --git a/arch/arm/kvm/mmio.c b/arch/arm/kvm/mmio.c > index 0f6600f..0158e9e 100644 > --- a/arch/arm/kvm/mmio.c > +++ b/arch/arm/kvm/mmio.c > @@ -87,11 +87,10 @@ static unsigned long mmio_read_buf(char *buf, unsigned int len) > > /** > * kvm_handle_mmio_return -- Handle MMIO loads after user space emulation > + * or in-kernel IO emulation > + * > * @vcpu: The VCPU pointer > * @run: The VCPU run struct containing the mmio data > - * > - * This should only be called after returning from userspace for MMIO load > - * emulation. > */ > int kvm_handle_mmio_return(struct kvm_vcpu *vcpu, struct kvm_run *run) > { > @@ -206,18 +205,19 @@ int io_mem_abort(struct kvm_vcpu *vcpu, struct kvm_run *run, > run->mmio.is_write = is_write; > run->mmio.phys_addr = fault_ipa; > run->mmio.len = len; > - if (is_write) > - memcpy(run->mmio.data, data_buf, len); > > if (!ret) { > /* We handled the access successfully in the kernel. */ > + if (!is_write) > + memcpy(run->mmio.data, data_buf, len); > vcpu->stat.mmio_exit_kernel++; > kvm_handle_mmio_return(vcpu, run); > return 1; > - } else { > - vcpu->stat.mmio_exit_user++; > } > > + if (is_write) > + memcpy(run->mmio.data, data_buf, len); > + vcpu->stat.mmio_exit_user++; > run->exit_reason = KVM_EXIT_MMIO; > return 0; > } > diff --git a/virt/kvm/arm/vgic.c b/virt/kvm/arm/vgic.c > index 00429b3..63e99cb 100644 > --- a/virt/kvm/arm/vgic.c > +++ b/virt/kvm/arm/vgic.c > @@ -850,12 +850,6 @@ static int vgic_handle_mmio_access(struct kvm_vcpu *vcpu, > updated_state = false; > } > spin_unlock(&dist->lock); > - run->mmio.is_write = is_write; > - run->mmio.len = len; > - run->mmio.phys_addr = addr; > - memcpy(run->mmio.data, val, len); > - > - kvm_handle_mmio_return(vcpu, run); > > if (updated_state) > vgic_kick_vcpus(vcpu->kvm); > -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Tue, Apr 05, 2016 at 01:12:04PM +0100, Andre Przywara wrote: > On 29/03/16 13:33, Christoffer Dall wrote: > > On Fri, Mar 25, 2016 at 02:04:24AM +0000, Andre Przywara wrote: > >> When the kernel was handling a guest MMIO access internally, we need > >> to copy the emulation result into the run->mmio structure in order > >> for the kvm_handle_mmio_return() function to pick it up and inject > >> the result back into the guest. > >> Currently the only user of kvm_io_bus for ARM is the VGIC, which did > >> this copying itself, so this was not causing issues so far. > >> But with upcoming kvm_io_bus users we need to do the copying here. > >> > >> Signed-off-by: Andre Przywara <andre.przywara@arm.com> > >> --- > >> arch/arm/kvm/mmio.c | 2 +- > >> 1 file changed, 1 insertion(+), 1 deletion(-) > >> > >> diff --git a/arch/arm/kvm/mmio.c b/arch/arm/kvm/mmio.c > >> index 0f6600f..d5c2727 100644 > >> --- a/arch/arm/kvm/mmio.c > >> +++ b/arch/arm/kvm/mmio.c > >> @@ -206,7 +206,7 @@ int io_mem_abort(struct kvm_vcpu *vcpu, struct kvm_run *run, > >> run->mmio.is_write = is_write; > >> run->mmio.phys_addr = fault_ipa; > >> run->mmio.len = len; > >> - if (is_write) > >> + if (is_write || !ret) > >> memcpy(run->mmio.data, data_buf, len); > > > > I had a really hard time understanding this, how about this instead: > > Admittedly this is the shortest possible fix. I also had a rework closer > to your version, which also avoided copying the arguments in some cases, > but I thought a smaller diff would be more suitable, since this is > actually a fix. > > Shall I add a comment here or post my version of the fix instead? > Let me test what I have below more thoroughly and send that as a patch. -Christoffer > > > diff --git a/arch/arm/kvm/mmio.c b/arch/arm/kvm/mmio.c > > index 0f6600f..0158e9e 100644 > > --- a/arch/arm/kvm/mmio.c > > +++ b/arch/arm/kvm/mmio.c > > @@ -87,11 +87,10 @@ static unsigned long mmio_read_buf(char *buf, unsigned int len) > > > > /** > > * kvm_handle_mmio_return -- Handle MMIO loads after user space emulation > > + * or in-kernel IO emulation > > + * > > * @vcpu: The VCPU pointer > > * @run: The VCPU run struct containing the mmio data > > - * > > - * This should only be called after returning from userspace for MMIO load > > - * emulation. > > */ > > int kvm_handle_mmio_return(struct kvm_vcpu *vcpu, struct kvm_run *run) > > { > > @@ -206,18 +205,19 @@ int io_mem_abort(struct kvm_vcpu *vcpu, struct kvm_run *run, > > run->mmio.is_write = is_write; > > run->mmio.phys_addr = fault_ipa; > > run->mmio.len = len; > > - if (is_write) > > - memcpy(run->mmio.data, data_buf, len); > > > > if (!ret) { > > /* We handled the access successfully in the kernel. */ > > + if (!is_write) > > + memcpy(run->mmio.data, data_buf, len); > > vcpu->stat.mmio_exit_kernel++; > > kvm_handle_mmio_return(vcpu, run); > > return 1; > > - } else { > > - vcpu->stat.mmio_exit_user++; > > } > > > > + if (is_write) > > + memcpy(run->mmio.data, data_buf, len); > > + vcpu->stat.mmio_exit_user++; > > run->exit_reason = KVM_EXIT_MMIO; > > return 0; > > } > > diff --git a/virt/kvm/arm/vgic.c b/virt/kvm/arm/vgic.c > > index 00429b3..63e99cb 100644 > > --- a/virt/kvm/arm/vgic.c > > +++ b/virt/kvm/arm/vgic.c > > @@ -850,12 +850,6 @@ static int vgic_handle_mmio_access(struct kvm_vcpu *vcpu, > > updated_state = false; > > } > > spin_unlock(&dist->lock); > > - run->mmio.is_write = is_write; > > - run->mmio.len = len; > > - run->mmio.phys_addr = addr; > > - memcpy(run->mmio.data, val, len); > > - > > - kvm_handle_mmio_return(vcpu, run); > > > > if (updated_state) > > vgic_kick_vcpus(vcpu->kvm); > > > -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/arch/arm/kvm/mmio.c b/arch/arm/kvm/mmio.c index 0f6600f..0158e9e 100644 --- a/arch/arm/kvm/mmio.c +++ b/arch/arm/kvm/mmio.c @@ -87,11 +87,10 @@ static unsigned long mmio_read_buf(char *buf, unsigned int len) /** * kvm_handle_mmio_return -- Handle MMIO loads after user space emulation + * or in-kernel IO emulation + * * @vcpu: The VCPU pointer * @run: The VCPU run struct containing the mmio data - * - * This should only be called after returning from userspace for MMIO load - * emulation. */ int kvm_handle_mmio_return(struct kvm_vcpu *vcpu, struct kvm_run *run) { @@ -206,18 +205,19 @@ int io_mem_abort(struct kvm_vcpu *vcpu, struct kvm_run *run, run->mmio.is_write = is_write; run->mmio.phys_addr = fault_ipa; run->mmio.len = len; - if (is_write) - memcpy(run->mmio.data, data_buf, len); if (!ret) { /* We handled the access successfully in the kernel. */ + if (!is_write) + memcpy(run->mmio.data, data_buf, len); vcpu->stat.mmio_exit_kernel++; kvm_handle_mmio_return(vcpu, run); return 1; - } else { - vcpu->stat.mmio_exit_user++; } + if (is_write) + memcpy(run->mmio.data, data_buf, len); + vcpu->stat.mmio_exit_user++; run->exit_reason = KVM_EXIT_MMIO; return 0; } diff --git a/virt/kvm/arm/vgic.c b/virt/kvm/arm/vgic.c index 00429b3..63e99cb 100644 --- a/virt/kvm/arm/vgic.c +++ b/virt/kvm/arm/vgic.c @@ -850,12 +850,6 @@ static int vgic_handle_mmio_access(struct kvm_vcpu *vcpu, updated_state = false; } spin_unlock(&dist->lock); - run->mmio.is_write = is_write; - run->mmio.len = len; - run->mmio.phys_addr = addr; - memcpy(run->mmio.data, val, len); - - kvm_handle_mmio_return(vcpu, run); if (updated_state) vgic_kick_vcpus(vcpu->kvm);