Re: [PATCH Part2 v5 21/45] KVM: SVM: Make AVIC backing, VMSA and VMCB memory allocation SNP safe
From: Sean Christopherson <seanjc@google.com>
Date: 2021-10-12 20:44:54
Also in:
kvm, linux-crypto, linux-mm, lkml
On Fri, Aug 20, 2021, Brijesh Singh wrote:
Implement a workaround for an SNP erratum where the CPU will incorrectly signal an RMP violation #PF if a hugepage (2mb or 1gb) collides with the RMP entry of a VMCB, VMSA or AVIC backing page.
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quoted hunk ↗ jump to hunk
@@ -4539,6 +4539,16 @@ static int svm_vm_init(struct kvm *kvm) return 0; } +static void *svm_alloc_apic_backing_page(struct kvm_vcpu *vcpu) +{ + struct page *page = snp_safe_alloc_page(vcpu); + + if (!page) + return NULL; + + return page_address(page); +} + static struct kvm_x86_ops svm_x86_ops __initdata = { .hardware_unsetup = svm_hardware_teardown, .hardware_enable = svm_hardware_enable,@@ -4667,6 +4677,8 @@ static struct kvm_x86_ops svm_x86_ops __initdata = { .complete_emulated_msr = svm_complete_emulated_msr, .vcpu_deliver_sipi_vector = svm_vcpu_deliver_sipi_vector, + + .alloc_apic_backing_page = svm_alloc_apic_backing_page,
IMO, this should be guarded by a module param or X86_BUG_* to make it clear that this is a bug and not working as intended. And doesn't the APIC page need these shenanigans iff AVIC is enabled? (the module param, not necessarily in the VM)
quoted hunk ↗ jump to hunk
}; static struct kvm_x86_init_ops svm_init_ops __initdata = {diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h index d1f1512a4b47..e40800e9c998 100644 --- a/arch/x86/kvm/svm/svm.h +++ b/arch/x86/kvm/svm/svm.h@@ -575,6 +575,7 @@ void sev_es_create_vcpu(struct vcpu_svm *svm); void sev_vcpu_deliver_sipi_vector(struct kvm_vcpu *vcpu, u8 vector); void sev_es_prepare_guest_switch(struct vcpu_svm *svm, unsigned int cpu); void sev_es_unmap_ghcb(struct vcpu_svm *svm); +struct page *snp_safe_alloc_page(struct kvm_vcpu *vcpu); /* vmenter.S */-- 2.17.1