Use the already-calculated-and-sanity-checked destination bitmap when
processing a fast AVIC kick in logical mode, and drop the logical path's
flawed logic. The intent of the check is to ensure the bitmap is a power
of two, whereas "icrh != (1 << avic)" effectively checks that the bitmap
is a power of two _and_ the target cluster is '0'.
Note, the flawed check isn't a functional issue, it simply means that KVM
will go down the slow path if the target cluster is non-zero.
Fixes: 8c9e639da435 ("KVM: SVM: Use target APIC ID to complete x2AVIC IRQs when possible")
Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
---
arch/x86/kvm/svm/avic.c | 10 +---------
1 file changed, 1 insertion(+), 9 deletions(-)
diff --git a/arch/x86/kvm/svm/avic.c b/arch/x86/kvm/svm/avic.c
index 3c333cd2e752..14f567550a1e 100644
--- a/arch/x86/kvm/svm/avic.c
+++ b/arch/x86/kvm/svm/avic.c
@@ -411,15 +411,7 @@ static int avic_kick_target_vcpus_fast(struct kvm *kvm, struct kvm_lapic *source
* Instead, calculate physical ID from logical ID in ICRH.
*/
int cluster = (icrh & 0xffff0000) >> 16;
- int apic = ffs(icrh & 0xffff) - 1;
-
- /*
- * If the x2APIC logical ID sub-field (i.e. icrh[15:0])
- * contains anything but a single bit, we cannot use the
- * fast path, because it is limited to a single vCPU.
- */
- if (apic < 0 || icrh != (1 << apic))
- return -EINVAL;
+ int apic = ffs(bitmap) - 1;
l1_physical_id = (cluster << 4) + apic;
}
--
2.37.2.672.g94769d06f0-goog
