WARN if generating a GATag given a VM ID and vCPU ID doesn't yield the
same IDs when pulling the IDs back out of the tag. Don't bother adding
error handling to callers, this is very much a paranoid sanity check as
KVM fully controls the VM ID and is supposed to reject too-big vCPU IDs.
Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
---
arch/x86/kvm/svm/avic.c | 15 ++++++++++++---
1 file changed, 12 insertions(+), 3 deletions(-)
diff --git a/arch/x86/kvm/svm/avic.c b/arch/x86/kvm/svm/avic.c
index 326341a22153..cfc8ab773025 100644
--- a/arch/x86/kvm/svm/avic.c
+++ b/arch/x86/kvm/svm/avic.c
@@ -43,12 +43,21 @@
#define AVIC_VM_ID_SHIFT HWEIGHT32(AVIC_PHYSICAL_MAX_INDEX_MASK)
#define AVIC_VM_ID_MASK (GENMASK(31, AVIC_VM_ID_SHIFT) >> AVIC_VM_ID_SHIFT)
-#define AVIC_GATAG(x, y) (((x & AVIC_VM_ID_MASK) << AVIC_VM_ID_SHIFT) | \
- (y & AVIC_VCPU_ID_MASK))
#define AVIC_GATAG_TO_VMID(x) ((x >> AVIC_VM_ID_SHIFT) & AVIC_VM_ID_MASK)
#define AVIC_GATAG_TO_VCPUID(x) (x & AVIC_VCPU_ID_MASK)
-static_assert(AVIC_GATAG(AVIC_VM_ID_MASK, AVIC_VCPU_ID_MASK) == -1u);
+#define __AVIC_GATAG(vm_id, vcpu_id) ((((vm_id) & AVIC_VM_ID_MASK) << AVIC_VM_ID_SHIFT) | \
+ ((vcpu_id) & AVIC_VCPU_ID_MASK))
+#define AVIC_GATAG(vm_id, vcpu_id) \
+({ \
+ u32 ga_tag = __AVIC_GATAG(vm_id, vcpu_id); \
+ \
+ WARN_ON_ONCE(AVIC_GATAG_TO_VCPUID(ga_tag) != (vcpu_id)); \
+ WARN_ON_ONCE(AVIC_GATAG_TO_VMID(ga_tag) != (vm_id)); \
+ ga_tag; \
+})
+
+static_assert(__AVIC_GATAG(AVIC_VM_ID_MASK, AVIC_VCPU_ID_MASK) == -1u);
static bool force_avic;
module_param_unsafe(force_avic, bool, 0444);
--
2.39.1.519.gcb327c4b5f-goog
