On Wed, 2021-10-13 at 12:56 -0400, Paolo Bonzini wrote:

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.

While at it, remove the void* argument also from emulator_pio_in_out.

s/remove the void* argument/remove the unused 'void* val' argument/ maybe?

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 | 42 +++++++++++++++++++++++------------------- 1 file changed, 23 insertions(+), 19 deletions(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 8880dc36a2b4..07d9533b471d 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 +6927,31 @@ 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, void *val, unsigned int count)
  

+static int __emulator_pio_in(struct kvm_vcpu *vcpu, int size,

• 	     unsigned short port, unsigned int count)
  

{

• int ret;
• if (vcpu->arch.pio.count)

• goto data_avail;
  

• WARN_ON(vcpu->arch.pio.count); memset(vcpu->arch.pio_data, 0, size * count);
• return emulator_pio_in_out(vcpu, size, port, count, true);

+}

• 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;
  

• }

+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;

+}

• return 0;

+static int emulator_pio_in(struct kvm_vcpu *vcpu, int size,

• 	   unsigned short port, void *val, unsigned int count)
  

+{

• if (!vcpu->arch.pio.count && !__emulator_pio_in(vcpu, size, port, count))

• return 0;
  

^^ maybe I would add a comment here about the fact that kernel completed the emulation when returing here.

• 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 +6970,11 @@ 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,

Reviewed-by: Maxim Levitsky mlevitsk@redhat.com

Best regards, Maxim Levitsky