diff options
| author | Sean Christopherson <seanjc@google.com> | 2025-06-11 15:45:14 -0700 |
|---|---|---|
| committer | Sean Christopherson <seanjc@google.com> | 2025-06-20 13:52:58 -0700 |
| commit | d8527f133c0a810b2e803a03aa186cfef721fbf8 (patch) | |
| tree | 106f5cd24d72a555e09782f093469bc47f0f2b48 | |
| parent | 3338c639da15a87cf57edc79de8409c98b704d87 (diff) | |
KVM: SVM: Drop vcpu_svm's pointless avic_backing_page field
Drop vcpu_svm's avic_backing_page pointer and instead grab the physical
address of KVM's vAPIC page directly from the source. Getting a physical
address from a kernel virtual address is not an expensive operation, and
getting the physical address from a struct page is *more* expensive for
CONFIG_SPARSEMEM=y kernels. Regardless, none of the paths that consume
the address are hot paths, i.e. shaving cycles is not a priority.
Eliminating the "cache" means KVM doesn't have to worry about the cache
being invalid, which will simplify a future fix when dealing with vCPU IDs
that are too big.
WARN if KVM attempts to allocate a vCPU's AVIC backing page without an
in-kernel local APIC. avic_init_vcpu() bails early if the APIC is not
in-kernel, and KVM disallows enabling an in-kernel APIC after vCPUs have
been created, i.e. it should be impossible to reach
avic_init_backing_page() without the vAPIC being allocated.
Tested-by: Sairaj Kodilkar <sarunkod@amd.com>
Reviewed-by: Naveen N Rao (AMD) <naveen@kernel.org>
Link: https://lore.kernel.org/r/20250611224604.313496-13-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
| -rw-r--r-- | arch/x86/kvm/svm/avic.c | 6 | ||||
| -rw-r--r-- | arch/x86/kvm/svm/svm.h | 1 |
2 files changed, 2 insertions, 5 deletions
diff --git a/arch/x86/kvm/svm/avic.c b/arch/x86/kvm/svm/avic.c index 75317c189409..f0401c1e355c 100644 --- a/arch/x86/kvm/svm/avic.c +++ b/arch/x86/kvm/svm/avic.c @@ -237,7 +237,7 @@ free_avic: static phys_addr_t avic_get_backing_page_address(struct vcpu_svm *svm) { - return __sme_set(page_to_phys(svm->avic_backing_page)); + return __sme_set(__pa(svm->vcpu.arch.apic->regs)); } void avic_init_vmcb(struct vcpu_svm *svm, struct vmcb *vmcb) @@ -282,7 +282,7 @@ static int avic_init_backing_page(struct kvm_vcpu *vcpu) (id > X2AVIC_MAX_PHYSICAL_ID)) return -EINVAL; - if (!vcpu->arch.apic->regs) + if (WARN_ON_ONCE(!vcpu->arch.apic->regs)) return -EINVAL; if (kvm_apicv_activated(vcpu->kvm)) { @@ -299,8 +299,6 @@ static int avic_init_backing_page(struct kvm_vcpu *vcpu) return ret; } - svm->avic_backing_page = virt_to_page(vcpu->arch.apic->regs); - /* Setting AVIC backing page address in the phy APIC ID table */ entry = avic_get_physical_id_entry(vcpu, id); if (!entry) diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h index cc27877d69ae..1585288200f4 100644 --- a/arch/x86/kvm/svm/svm.h +++ b/arch/x86/kvm/svm/svm.h @@ -306,7 +306,6 @@ struct vcpu_svm { u32 ldr_reg; u32 dfr_reg; - struct page *avic_backing_page; u64 *avic_physical_id_cache; /* |