When sending IPI in the X2APIC logical cluster mode, the destination
APIC ID is encoded as:
* Cluster ID = ICRH[31:16]
* Logical ID = ICRH[15:0]
Current logic incorrectly decode the ICRH, which causes VM running
with x2AVIC support to fail to boot. Therefore, fix the decoding logic.
The commit 603ccef42ce9 ("KVM: x86: SVM: fix avic_kick_target_vcpus_fast")
also added a check for multiple logical destinations before using
the fast-path. However, the same logic is already existed prior to
the commit. Therefore, remove redundant checking logic.
Fixes: 603ccef42ce9 ("KVM: x86: SVM: fix avic_kick_target_vcpus_fast")
Cc: Maxim Levitsky <mlevitsk@xxxxxxxxxx>
Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@xxxxxxx>
---
arch/x86/kvm/svm/avic.c | 19 ++++---------------
1 file changed, 4 insertions(+), 15 deletions(-)
diff --git a/arch/x86/kvm/svm/avic.c b/arch/x86/kvm/svm/avic.c
index 6919dee69f18..45ab49d1f0b8 100644
--- a/arch/x86/kvm/svm/avic.c
+++ b/arch/x86/kvm/svm/avic.c
@@ -378,8 +378,8 @@ static int avic_kick_target_vcpus_fast(struct kvm *kvm, struct kvm_lapic *source
if (apic_x2apic_mode(source)) {
/* 16 bit dest mask, 16 bit cluster id */
- bitmap = dest & 0xFFFF0000;
- cluster = (dest >> 16) << 4;
+ bitmap = dest & 0xffff;
+ cluster = (dest & 0xffff0000) >> 16;
} else if (kvm_lapic_get_reg(source, APIC_DFR) == APIC_DFR_FLAT) {
/* 8 bit dest mask*/
bitmap = dest;
@@ -387,7 +387,7 @@ static int avic_kick_target_vcpus_fast(struct kvm *kvm, struct kvm_lapic *source
} else {
/* 4 bit desk mask, 4 bit cluster id */
bitmap = dest & 0xF;
- cluster = (dest >> 4) << 2;
+ cluster = (dest & 0xf0) >> 4;
}
if (unlikely(!bitmap))
@@ -420,18 +420,7 @@ static int avic_kick_target_vcpus_fast(struct kvm *kvm, struct kvm_lapic *source
* For x2APIC logical mode, cannot leverage the index.
* 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;
-
- l1_physical_id = (cluster << 4) + apic;
+ l1_physical_id = (cluster << 4) + (ffs(bitmap) - 1);
}
}
--
2.34.1
