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KVM: x86: split the two parts of emulator_pio_in

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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: 7ed9abfe8e ("KVM: SVM: Support string IO operations for an SEV-ES guest")
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Paolo Bonzini 2021-10-13 12:32:02 -04:00
parent ea724ea420
commit 3b27de2718
1 changed files with 28 additions and 17 deletions
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45
arch/x86/kvm/x86.c
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@ -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, 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) unsigned int count, bool in)
{ {
vcpu->arch.pio.port = port; vcpu->arch.pio.port = port;
@ -6927,26 +6927,38 @@ static int emulator_pio_in_out(struct kvm_vcpu *vcpu, int size,
return 0; 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, static int emulator_pio_in(struct kvm_vcpu *vcpu, int size,
unsigned short port, void *val, unsigned int count) 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) /* Results already available, fall through. */
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;
} }
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, 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); memcpy(vcpu->arch.pio_data, val, size * count);
trace_kvm_pio(KVM_PIO_OUT, port, size, count, vcpu->arch.pio_data); 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) if (ret)
vcpu->arch.pio.count = 0; vcpu->arch.pio.count = 0;
return ret; return ret;
} }
static int emulator_pio_out_emulated(struct x86_emulate_ctxt *ctxt, static int emulator_pio_out_emulated(struct x86_emulate_ctxt *ctxt,