From 9bf418335e24da995ea682a028926d7e1036be6f Mon Sep 17 00:00:00 2001
From: Jan Kiszka <jan.kiszka@siemens.com>
Date: Mon, 30 Jun 2014 10:54:17 +0200
Subject: [PATCH] KVM: nSVM: Fix IOIO bitmap evaluation
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@siemens.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
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 c79766e1f1e04..3483ac978c76e 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)
--
2.50.1