Commit 3b27de27 authored by Paolo Bonzini's avatar Paolo Bonzini
Browse files

KVM: x86: split the two parts of emulator_pio_in 



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: 7ed9abfe ("KVM: SVM: Support string IO operations for an SEV-ES guest")
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent ea724ea4

arch/x86/kvm/x86.c

+28 −17
Original line number Diff line number Diff line
@@ -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, 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);

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 1;

}



	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) {

		/* Complete previous iteration.  */

	} else {

		int r = __emulator_pio_in(vcpu, size, port, count);

		if (!r)

			return r;



		/* Results already available, fall through.  */

	}



	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,