Message ID | 20211013165616.19846-9-pbonzini@redhat.com (mailing list archive) |
---|---|
State | New, archived |
Headers | show |
Series | KVM: SEV-ES: fixes for string I/O emulation | expand |
On Wed, 2021-10-13 at 12:56 -0400, Paolo Bonzini wrote: > The PIO scratch buffer is larger than a single page, and therefore > it is not possible to copy it in a single step to vcpu->arch/pio_data. > Bound each call to emulator_pio_in/out to a single page; keep > track of how many I/O operations are left in vcpu->arch.sev_pio_count, > so that the operation can be restarted in the complete_userspace_io > callback. > > For OUT, this means that the previous kvm_sev_es_outs implementation > becomes an iterator of the loop, and we can consume the sev_pio_data > buffer before leaving to userspace. > > For IN, instead, consuming the buffer and decreasing sev_pio_count > is always done in the complete_userspace_io callback, because that > is when the memcpy is done into sev_pio_data. > > Cc: stable@vger.kernel.org > Fixes: 7ed9abfe8e9f ("KVM: SVM: Support string IO operations for an SEV-ES guest") > Reported-by: Felix Wilhelm <fwilhelm@google.com> > Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> > --- > arch/x86/include/asm/kvm_host.h | 1 + > arch/x86/kvm/x86.c | 73 +++++++++++++++++++++++++-------- > 2 files changed, 57 insertions(+), 17 deletions(-) > > diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h > index 6bed6c416c6c..5a0298aa56ba 100644 > --- a/arch/x86/include/asm/kvm_host.h > +++ b/arch/x86/include/asm/kvm_host.h > @@ -703,6 +703,7 @@ struct kvm_vcpu_arch { > struct kvm_pio_request pio; > void *pio_data; > void *sev_pio_data; > + unsigned sev_pio_count; > > u8 event_exit_inst_len; > > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index a485e185ad00..09c1e64495d3 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -12378,38 +12378,76 @@ int kvm_sev_es_mmio_read(struct kvm_vcpu *vcpu, gpa_t gpa, unsigned int bytes, > EXPORT_SYMBOL_GPL(kvm_sev_es_mmio_read); > > static int kvm_sev_es_outs(struct kvm_vcpu *vcpu, unsigned int size, > - unsigned int port, unsigned int count) > + unsigned int port); > + > +static int complete_sev_es_emulated_outs(struct kvm_vcpu *vcpu) > { > - int ret = emulator_pio_out(vcpu, size, port, > - vcpu->arch.sev_pio_data, count); > + vcpu->arch.pio.count = 0; > + if (vcpu->arch.sev_pio_count) > + return kvm_sev_es_outs(vcpu, > + vcpu->arch.pio.size, > + vcpu->arch.pio.port); > + return 1; > +} > + > +static int kvm_sev_es_outs(struct kvm_vcpu *vcpu, unsigned int size, > + unsigned int port) > +{ > + for (;;) { > + unsigned int count = > + min_t(unsigned int, PAGE_SIZE / size, vcpu->arch.sev_pio_count); > + int ret = emulator_pio_out(vcpu, size, port, vcpu->arch.sev_pio_data, count); > + > + /* memcpy done already by emulator_pio_out. */ > + vcpu->arch.sev_pio_count -= count; > + vcpu->arch.sev_pio_data += count * vcpu->arch.pio.size; > + if (!ret) > + break; > > - if (ret) { > /* Emulation done by the kernel. */ > - return ret; > + vcpu->arch.pio.count = 0; > + if (!vcpu->arch.sev_pio_count) > + return 1; > } > > - vcpu->arch.pio.count = 0; > + vcpu->arch.complete_userspace_io = complete_sev_es_emulated_outs; > return 0; > } > > -static int complete_sev_es_emulated_ins(struct kvm_vcpu *vcpu) > +static int kvm_sev_es_ins(struct kvm_vcpu *vcpu, unsigned int size, > + unsigned int port); > + > +static void __complete_sev_es_emulated_ins(struct kvm_vcpu *vcpu) > { > - memcpy(vcpu->arch.sev_pio_data, vcpu->arch.pio_data, > - vcpu->arch.pio.count * vcpu->arch.pio.size); > - vcpu->arch.pio.count = 0; > + unsigned count = vcpu->arch.pio.count; > + complete_emulator_pio_in(vcpu, vcpu->arch.sev_pio_data); > + vcpu->arch.sev_pio_count -= count; > + vcpu->arch.sev_pio_data += count * vcpu->arch.pio.size; > +} > > +static int complete_sev_es_emulated_ins(struct kvm_vcpu *vcpu) > +{ > + __complete_sev_es_emulated_ins(vcpu); > + if (vcpu->arch.sev_pio_count) > + return kvm_sev_es_ins(vcpu, > + vcpu->arch.pio.size, > + vcpu->arch.pio.port); > return 1; > } > > static int kvm_sev_es_ins(struct kvm_vcpu *vcpu, unsigned int size, > - unsigned int port, unsigned int count) > + unsigned int port) > { > - int ret = emulator_pio_in(vcpu, size, port, > - vcpu->arch.sev_pio_data, count); > + for (;;) { > + unsigned int count = > + min_t(unsigned int, PAGE_SIZE / size, vcpu->arch.sev_pio_count); > + if (!__emulator_pio_in(vcpu, size, port, count)) > + break; > > - if (ret) { > /* Emulation done by the kernel. */ > - return ret; > + __complete_sev_es_emulated_ins(vcpu); > + if (!vcpu->arch.sev_pio_count) > + return 1; > } > > vcpu->arch.complete_userspace_io = complete_sev_es_emulated_ins; > @@ -12421,8 +12459,9 @@ int kvm_sev_es_string_io(struct kvm_vcpu *vcpu, unsigned int size, > int in) > { > vcpu->arch.sev_pio_data = data; > - return in ? kvm_sev_es_ins(vcpu, size, port, count) > - : kvm_sev_es_outs(vcpu, size, port, count); > + vcpu->arch.sev_pio_count = count; > + return in ? kvm_sev_es_ins(vcpu, size, port) > + : kvm_sev_es_outs(vcpu, size, port); > } > EXPORT_SYMBOL_GPL(kvm_sev_es_string_io); > I might have missed something, but it looks OK to me. i mostly checked how the code looks after applying this patch. Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com> Note that I haven't run tested the patches as I don't currently test SEV-ES. Best regards, Maxim Levitsky
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index 6bed6c416c6c..5a0298aa56ba 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -703,6 +703,7 @@ struct kvm_vcpu_arch { struct kvm_pio_request pio; void *pio_data; void *sev_pio_data; + unsigned sev_pio_count; u8 event_exit_inst_len; diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index a485e185ad00..09c1e64495d3 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -12378,38 +12378,76 @@ int kvm_sev_es_mmio_read(struct kvm_vcpu *vcpu, gpa_t gpa, unsigned int bytes, EXPORT_SYMBOL_GPL(kvm_sev_es_mmio_read); static int kvm_sev_es_outs(struct kvm_vcpu *vcpu, unsigned int size, - unsigned int port, unsigned int count) + unsigned int port); + +static int complete_sev_es_emulated_outs(struct kvm_vcpu *vcpu) { - int ret = emulator_pio_out(vcpu, size, port, - vcpu->arch.sev_pio_data, count); + vcpu->arch.pio.count = 0; + if (vcpu->arch.sev_pio_count) + return kvm_sev_es_outs(vcpu, + vcpu->arch.pio.size, + vcpu->arch.pio.port); + return 1; +} + +static int kvm_sev_es_outs(struct kvm_vcpu *vcpu, unsigned int size, + unsigned int port) +{ + for (;;) { + unsigned int count = + min_t(unsigned int, PAGE_SIZE / size, vcpu->arch.sev_pio_count); + int ret = emulator_pio_out(vcpu, size, port, vcpu->arch.sev_pio_data, count); + + /* memcpy done already by emulator_pio_out. */ + vcpu->arch.sev_pio_count -= count; + vcpu->arch.sev_pio_data += count * vcpu->arch.pio.size; + if (!ret) + break; - if (ret) { /* Emulation done by the kernel. */ - return ret; + vcpu->arch.pio.count = 0; + if (!vcpu->arch.sev_pio_count) + return 1; } - vcpu->arch.pio.count = 0; + vcpu->arch.complete_userspace_io = complete_sev_es_emulated_outs; return 0; } -static int complete_sev_es_emulated_ins(struct kvm_vcpu *vcpu) +static int kvm_sev_es_ins(struct kvm_vcpu *vcpu, unsigned int size, + unsigned int port); + +static void __complete_sev_es_emulated_ins(struct kvm_vcpu *vcpu) { - memcpy(vcpu->arch.sev_pio_data, vcpu->arch.pio_data, - vcpu->arch.pio.count * vcpu->arch.pio.size); - vcpu->arch.pio.count = 0; + unsigned count = vcpu->arch.pio.count; + complete_emulator_pio_in(vcpu, vcpu->arch.sev_pio_data); + vcpu->arch.sev_pio_count -= count; + vcpu->arch.sev_pio_data += count * vcpu->arch.pio.size; +} +static int complete_sev_es_emulated_ins(struct kvm_vcpu *vcpu) +{ + __complete_sev_es_emulated_ins(vcpu); + if (vcpu->arch.sev_pio_count) + return kvm_sev_es_ins(vcpu, + vcpu->arch.pio.size, + vcpu->arch.pio.port); return 1; } static int kvm_sev_es_ins(struct kvm_vcpu *vcpu, unsigned int size, - unsigned int port, unsigned int count) + unsigned int port) { - int ret = emulator_pio_in(vcpu, size, port, - vcpu->arch.sev_pio_data, count); + for (;;) { + unsigned int count = + min_t(unsigned int, PAGE_SIZE / size, vcpu->arch.sev_pio_count); + if (!__emulator_pio_in(vcpu, size, port, count)) + break; - if (ret) { /* Emulation done by the kernel. */ - return ret; + __complete_sev_es_emulated_ins(vcpu); + if (!vcpu->arch.sev_pio_count) + return 1; } vcpu->arch.complete_userspace_io = complete_sev_es_emulated_ins; @@ -12421,8 +12459,9 @@ int kvm_sev_es_string_io(struct kvm_vcpu *vcpu, unsigned int size, int in) { vcpu->arch.sev_pio_data = data; - return in ? kvm_sev_es_ins(vcpu, size, port, count) - : kvm_sev_es_outs(vcpu, size, port, count); + vcpu->arch.sev_pio_count = count; + return in ? kvm_sev_es_ins(vcpu, size, port) + : kvm_sev_es_outs(vcpu, size, port); } EXPORT_SYMBOL_GPL(kvm_sev_es_string_io);
The PIO scratch buffer is larger than a single page, and therefore it is not possible to copy it in a single step to vcpu->arch/pio_data. Bound each call to emulator_pio_in/out to a single page; keep track of how many I/O operations are left in vcpu->arch.sev_pio_count, so that the operation can be restarted in the complete_userspace_io callback. For OUT, this means that the previous kvm_sev_es_outs implementation becomes an iterator of the loop, and we can consume the sev_pio_data buffer before leaving to userspace. For IN, instead, consuming the buffer and decreasing sev_pio_count is always done in the complete_userspace_io callback, because that is when the memcpy is done into sev_pio_data. Cc: stable@vger.kernel.org Fixes: 7ed9abfe8e9f ("KVM: SVM: Support string IO operations for an SEV-ES guest") Reported-by: Felix Wilhelm <fwilhelm@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> --- arch/x86/include/asm/kvm_host.h | 1 + arch/x86/kvm/x86.c | 73 +++++++++++++++++++++++++-------- 2 files changed, 57 insertions(+), 17 deletions(-)