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authorSuravee Suthikulpanit <suravee.suthikulpanit@amd.com>2023-02-07 00:21:55 +0000
committerPaolo Bonzini <pbonzini@redhat.com>2023-03-14 10:20:06 -0400
commit5999715922c5a3ede5d8fe2a6b17aba58a157d41 (patch)
tree0c96eeefeea1a1a0feda58700b21b1216580eee3 /arch
parent3ec7a1b2743c07c45f4a0c508114f6cb410ddef3 (diff)
KVM: SVM: Modify AVIC GATag to support max number of 512 vCPUs
Define AVIC_VCPU_ID_MASK based on AVIC_PHYSICAL_MAX_INDEX, i.e. the mask that effectively controls the largest guest physical APIC ID supported by x2AVIC, instead of hardcoding the number of bits to 8 (and the number of VM bits to 24). The AVIC GATag is programmed into the AMD IOMMU IRTE to provide a reference back to KVM in case the IOMMU cannot inject an interrupt into a non-running vCPU. In such a case, the IOMMU notifies software by creating a GALog entry with the corresponded GATag, and KVM then uses the GATag to find the correct VM+vCPU to kick. Dropping bit 8 from the GATag results in kicking the wrong vCPU when targeting vCPUs with x2APIC ID > 255. Fixes: 4d1d7942e36a ("KVM: SVM: Introduce logic to (de)activate x2AVIC mode") Cc: stable@vger.kernel.org Reported-by: Alejandro Jimenez <alejandro.j.jimenez@oracle.com> Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com> Co-developed-by: Sean Christopherson <seanjc@google.com> Signed-off-by: Sean Christopherson <seanjc@google.com> Reviewed-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com> Tested-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com> Message-Id: <20230207002156.521736-3-seanjc@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'arch')
-rw-r--r--arch/x86/kvm/svm/avic.c26
1 files changed, 18 insertions, 8 deletions
diff --git a/arch/x86/kvm/svm/avic.c b/arch/x86/kvm/svm/avic.c
index ca684979e90d..326341a22153 100644
--- a/arch/x86/kvm/svm/avic.c
+++ b/arch/x86/kvm/svm/avic.c
@@ -27,19 +27,29 @@
#include "irq.h"
#include "svm.h"
-/* AVIC GATAG is encoded using VM and VCPU IDs */
-#define AVIC_VCPU_ID_BITS 8
-#define AVIC_VCPU_ID_MASK ((1 << AVIC_VCPU_ID_BITS) - 1)
+/*
+ * Encode the arbitrary VM ID and the vCPU's default APIC ID, i.e the vCPU ID,
+ * into the GATag so that KVM can retrieve the correct vCPU from a GALog entry
+ * if an interrupt can't be delivered, e.g. because the vCPU isn't running.
+ *
+ * For the vCPU ID, use however many bits are currently allowed for the max
+ * guest physical APIC ID (limited by the size of the physical ID table), and
+ * use whatever bits remain to assign arbitrary AVIC IDs to VMs. Note, the
+ * size of the GATag is defined by hardware (32 bits), but is an opaque value
+ * as far as hardware is concerned.
+ */
+#define AVIC_VCPU_ID_MASK AVIC_PHYSICAL_MAX_INDEX_MASK
-#define AVIC_VM_ID_BITS 24
-#define AVIC_VM_ID_NR (1 << AVIC_VM_ID_BITS)
-#define AVIC_VM_ID_MASK ((1 << AVIC_VM_ID_BITS) - 1)
+#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_VCPU_ID_BITS) | \
+#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_VCPU_ID_BITS) & AVIC_VM_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);
+
static bool force_avic;
module_param_unsafe(force_avic, bool, 0444);