From c281794eaa5c635c0edf39c6a9a3b0171000e92f Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Tue, 7 Feb 2023 00:21:56 +0000 Subject: [PATCH] KVM: SVM: WARN if GATag generation drops VM or vCPU ID information 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 Reviewed-by: Suravee Suthikulpanit Tested-by: Suravee Suthikulpanit Message-Id: <20230207002156.521736-4-seanjc@google.com> Signed-off-by: Paolo Bonzini --- 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);