From: Jan Kiszka <jan.kiszka@xxxxxxxxxxx>
First, kvm_read_guest returns 0 on success. And then we need to take the
access size into account when testing the bitmap: intercept if any of
bits corresponding to the access is set.
Signed-off-by: Jan Kiszka <jan.kiszka@xxxxxxxxxxx>
---
This does not yet solve all IOIO issues, there are emulation-related
bugs remaining, but this fix is self-contained.
arch/x86/kvm/svm.c | 19 ++++++++++++-------
1 file changed, 12 insertions(+), 7 deletions(-)
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index c79766e1..3483ac9 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -2116,22 +2116,27 @@ static void nested_svm_unmap(struct page *page)
static int nested_svm_intercept_ioio(struct vcpu_svm *svm)
{
- unsigned port;
- u8 val, bit;
+ unsigned port, size, iopm_len;
+ u16 val, mask;
+ u8 start_bit;
u64 gpa;
if (!(svm->nested.intercept & (1ULL << INTERCEPT_IOIO_PROT)))
return NESTED_EXIT_HOST;
port = svm->vmcb->control.exit_info_1 >> 16;
+ size = (svm->vmcb->control.exit_info_1 & SVM_IOIO_SIZE_MASK) >>
+ SVM_IOIO_SIZE_SHIFT;
gpa = svm->nested.vmcb_iopm + (port / 8);
- bit = port % 8;
- val = 0;
+ start_bit = port % 8;
+ iopm_len = (start_bit + size > 8) ? 2 : 1;
+ mask = (0xf >> (4 - size)) << start_bit;
+ val = 0;
- if (kvm_read_guest(svm->vcpu.kvm, gpa, &val, 1))
- val &= (1 << bit);
+ if (kvm_read_guest(svm->vcpu.kvm, gpa, &val, iopm_len))
+ return NESTED_EXIT_DONE;
- return val ? NESTED_EXIT_DONE : NESTED_EXIT_HOST;
+ return (val & mask) ? NESTED_EXIT_DONE : NESTED_EXIT_HOST;
}
static int nested_svm_exit_handled_msr(struct vcpu_svm *svm)
--
1.8.4.5
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