emulator_pio_in handles both the case where the data is pending in vcpu->arch.pio.count, and the case where I/O has to be done via either an in-kernel device or a userspace exit. For SEV-ES we would like to split these, to identify clearly the moment at which the sev_pio_data is consumed. To this end, create two different functions: __emulator_pio_in fills in vcpu->arch.pio.count, while complete_emulator_pio_in clears it and releases vcpu->arch.pio.data.

Because this patch has to be backported, things are left a bit messy. kernel_pio() operates on vcpu->arch.pio, which leads to emulator_pio_in() having with two calls to complete_emulator_pio_in(). It will be fixed in the next release.

While at it, remove the unused void* val argument of emulator_pio_in_out. The function currently hardcodes vcpu->arch.pio_data as the source/destination buffer, which sucks but will be fixed after the more severe SEV-ES buffer overflow.

No functional change intended.

Cc: stable@vger.kernel.org Fixes: 7ed9abfe8e9f ("KVM: SVM: Support string IO operations for an SEV-ES guest") Signed-off-by: Paolo Bonzini pbonzini@redhat.com --- arch/x86/kvm/x86.c | 45 ++++++++++++++++++++++++++++----------------- 1 file changed, 28 insertions(+), 17 deletions(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 78ed0fe9fa1e..c51ea81019e3 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -6906,7 +6906,7 @@ static int kernel_pio(struct kvm_vcpu *vcpu, void *pd) }

static int emulator_pio_in_out(struct kvm_vcpu *vcpu, int size, - unsigned short port, void *val, + unsigned short port, unsigned int count, bool in) { vcpu->arch.pio.port = port; @@ -6927,26 +6927,38 @@ static int emulator_pio_in_out(struct kvm_vcpu *vcpu, int size, return 0; }

+static int __emulator_pio_in(struct kvm_vcpu *vcpu, int size, + unsigned short port, unsigned int count) +{ + WARN_ON(vcpu->arch.pio.count); + memset(vcpu->arch.pio_data, 0, size * count); + return emulator_pio_in_out(vcpu, size, port, count, true); +} + +static void complete_emulator_pio_in(struct kvm_vcpu *vcpu, int size, + unsigned short port, void *val) +{ + memcpy(val, vcpu->arch.pio_data, size * vcpu->arch.pio.count); + trace_kvm_pio(KVM_PIO_IN, port, size, vcpu->arch.pio.count, vcpu->arch.pio_data); + vcpu->arch.pio.count = 0; +} + static int emulator_pio_in(struct kvm_vcpu *vcpu, int size, unsigned short port, void *val, unsigned int count) { - int ret; + if (vcpu->arch.pio.count) { + /* Complete previous iteration. */ + } else { + int r = __emulator_pio_in(vcpu, size, port, count); + if (!r) + return r;

- if (vcpu->arch.pio.count) - goto data_avail; - - memset(vcpu->arch.pio_data, 0, size * count); - - ret = emulator_pio_in_out(vcpu, size, port, val, count, true); - if (ret) { -data_avail: - memcpy(val, vcpu->arch.pio_data, size * count); - trace_kvm_pio(KVM_PIO_IN, port, size, count, vcpu->arch.pio_data); - vcpu->arch.pio.count = 0; - return 1; + /* Results already available, fall through. */ }

- return 0; + WARN_ON(count != vcpu->arch.pio.count); + complete_emulator_pio_in(vcpu, size, port, val); + return 1; }

static int emulator_pio_in_emulated(struct x86_emulate_ctxt *ctxt, @@ -6965,12 +6977,11 @@ static int emulator_pio_out(struct kvm_vcpu *vcpu, int size,

memcpy(vcpu->arch.pio_data, val, size * count); trace_kvm_pio(KVM_PIO_OUT, port, size, count, vcpu->arch.pio_data); - ret = emulator_pio_in_out(vcpu, size, port, (void *)val, count, false); + ret = emulator_pio_in_out(vcpu, size, port, count, false); if (ret) vcpu->arch.pio.count = 0;

return ret; - }

static int emulator_pio_out_emulated(struct x86_emulate_ctxt *ctxt,