From: Paolo Bonzini pbonzini@redhat.com
commit 95e16b4792b0429f1933872f743410f00e590c55 upstream.
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 Reviewed-by: Maxim Levitsky mlevitsk@redhat.com Signed-off-by: Paolo Bonzini pbonzini@redhat.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/x86/include/asm/kvm_host.h | 1 arch/x86/kvm/x86.c | 72 +++++++++++++++++++++++++++++++--------- 2 files changed, 57 insertions(+), 16 deletions(-)
--- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -696,6 +696,7 @@ 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;
--- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -12321,38 +12321,77 @@ int kvm_sev_es_mmio_read(struct kvm_vcpu 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 size = vcpu->arch.pio.size; + int port = vcpu->arch.pio.port; + + vcpu->arch.pio.count = 0; + if (vcpu->arch.sev_pio_count) + return kvm_sev_es_outs(vcpu, size, port); + return 1; +} + +static int kvm_sev_es_outs(struct kvm_vcpu *vcpu, unsigned int size, + unsigned int port) { - int ret = emulator_pio_out(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); + 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; + 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 kvm_sev_es_ins(struct kvm_vcpu *vcpu, unsigned int size, + unsigned int port); + +static void advance_sev_es_emulated_ins(struct kvm_vcpu *vcpu) +{ + 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) { - memcpy(vcpu->arch.sev_pio_data, vcpu->arch.pio_data, - vcpu->arch.pio.count * vcpu->arch.pio.size); - vcpu->arch.pio.count = 0; + int size = vcpu->arch.pio.size; + int port = vcpu->arch.pio.port;
+ advance_sev_es_emulated_ins(vcpu); + if (vcpu->arch.sev_pio_count) + return kvm_sev_es_ins(vcpu, size, 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; + advance_sev_es_emulated_ins(vcpu); + if (!vcpu->arch.sev_pio_count) + return 1; }
vcpu->arch.complete_userspace_io = complete_sev_es_emulated_ins; @@ -12364,8 +12403,9 @@ int kvm_sev_es_string_io(struct kvm_vcpu 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);