From: Jan Kiszka <[email protected]> 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 <[email protected]> --- 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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