From 255cbecfe0c9466ade041fe381dde18a61cca549 Mon Sep 17 00:00:00 2001 From: Vitaly Kuznetsov Date: Thu, 1 Oct 2020 15:05:40 +0200 Subject: [PATCH] KVM: x86: allocate vcpu->arch.cpuid_entries dynamically The current limit for guest CPUID leaves (KVM_MAX_CPUID_ENTRIES, 80) is reported to be insufficient but before we bump it let's switch to allocating vcpu->arch.cpuid_entries[] array dynamically. Currently, 'struct kvm_cpuid_entry2' is 40 bytes so vcpu->arch.cpuid_entries is 3200 bytes which accounts for 1/4 of the whole 'struct kvm_vcpu_arch' but having it pre-allocated (for all vCPUs which we also pre-allocate) gives us no real benefits. Another plus of the dynamic allocation is that we now do kvm_check_cpuid() check before we assign anything to vcpu->arch.cpuid_nent/cpuid_entries so no changes are made in case the check fails. Opportunistically remove unneeded 'out' labels from kvm_vcpu_ioctl_set_cpuid()/kvm_vcpu_ioctl_set_cpuid2() and return directly whenever possible. Signed-off-by: Vitaly Kuznetsov Message-Id: <20201001130541.1398392-3-vkuznets@redhat.com> Signed-off-by: Paolo Bonzini Reviewed-by: Maxim Levitsky --- arch/x86/include/asm/kvm_host.h | 2 +- arch/x86/kvm/cpuid.c | 89 +++++++++++++++++++-------------- arch/x86/kvm/x86.c | 1 + 3 files changed, 53 insertions(+), 39 deletions(-) diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index 15e51343957e2..8c44a82abe547 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -637,7 +637,7 @@ struct kvm_vcpu_arch { int halt_request; /* real mode on Intel only */ int cpuid_nent; - struct kvm_cpuid_entry2 cpuid_entries[KVM_MAX_CPUID_ENTRIES]; + struct kvm_cpuid_entry2 *cpuid_entries; int maxphyaddr; int max_tdp_level; diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c index 2e4228ccbe2ae..5a62fa4ee493e 100644 --- a/arch/x86/kvm/cpuid.c +++ b/arch/x86/kvm/cpuid.c @@ -217,46 +217,53 @@ int kvm_vcpu_ioctl_set_cpuid(struct kvm_vcpu *vcpu, struct kvm_cpuid_entry __user *entries) { int r, i; - struct kvm_cpuid_entry *cpuid_entries = NULL; + struct kvm_cpuid_entry *e = NULL; + struct kvm_cpuid_entry2 *e2 = NULL; - r = -E2BIG; if (cpuid->nent > KVM_MAX_CPUID_ENTRIES) - goto out; + return -E2BIG; + if (cpuid->nent) { - cpuid_entries = vmemdup_user(entries, - array_size(sizeof(struct kvm_cpuid_entry), - cpuid->nent)); - if (IS_ERR(cpuid_entries)) { - r = PTR_ERR(cpuid_entries); - goto out; + e = vmemdup_user(entries, array_size(sizeof(*e), cpuid->nent)); + if (IS_ERR(e)) + return PTR_ERR(e); + + e2 = kvmalloc_array(cpuid->nent, sizeof(*e2), GFP_KERNEL_ACCOUNT); + if (!e2) { + r = -ENOMEM; + goto out_free_cpuid; } } for (i = 0; i < cpuid->nent; i++) { - vcpu->arch.cpuid_entries[i].function = cpuid_entries[i].function; - vcpu->arch.cpuid_entries[i].eax = cpuid_entries[i].eax; - vcpu->arch.cpuid_entries[i].ebx = cpuid_entries[i].ebx; - vcpu->arch.cpuid_entries[i].ecx = cpuid_entries[i].ecx; - vcpu->arch.cpuid_entries[i].edx = cpuid_entries[i].edx; - vcpu->arch.cpuid_entries[i].index = 0; - vcpu->arch.cpuid_entries[i].flags = 0; - vcpu->arch.cpuid_entries[i].padding[0] = 0; - vcpu->arch.cpuid_entries[i].padding[1] = 0; - vcpu->arch.cpuid_entries[i].padding[2] = 0; + e2[i].function = e[i].function; + e2[i].eax = e[i].eax; + e2[i].ebx = e[i].ebx; + e2[i].ecx = e[i].ecx; + e2[i].edx = e[i].edx; + e2[i].index = 0; + e2[i].flags = 0; + e2[i].padding[0] = 0; + e2[i].padding[1] = 0; + e2[i].padding[2] = 0; } - vcpu->arch.cpuid_nent = cpuid->nent; - r = kvm_check_cpuid(vcpu->arch.cpuid_entries, cpuid->nent); + + r = kvm_check_cpuid(e2, cpuid->nent); if (r) { - vcpu->arch.cpuid_nent = 0; - kvfree(cpuid_entries); - goto out; + kvfree(e2); + goto out_free_cpuid; } + kvfree(vcpu->arch.cpuid_entries); + vcpu->arch.cpuid_entries = e2; + vcpu->arch.cpuid_nent = cpuid->nent; + cpuid_fix_nx_cap(vcpu); kvm_update_cpuid_runtime(vcpu); kvm_vcpu_after_set_cpuid(vcpu); - kvfree(cpuid_entries); -out: +out_free_cpuid: + kvfree(e); + return r; } @@ -264,26 +271,32 @@ int kvm_vcpu_ioctl_set_cpuid2(struct kvm_vcpu *vcpu, struct kvm_cpuid2 *cpuid, struct kvm_cpuid_entry2 __user *entries) { + struct kvm_cpuid_entry2 *e2 = NULL; int r; - r = -E2BIG; if (cpuid->nent > KVM_MAX_CPUID_ENTRIES) - goto out; - r = -EFAULT; - if (copy_from_user(&vcpu->arch.cpuid_entries, entries, - cpuid->nent * sizeof(struct kvm_cpuid_entry2))) - goto out; - vcpu->arch.cpuid_nent = cpuid->nent; - r = kvm_check_cpuid(vcpu->arch.cpuid_entries, cpuid->nent); + return -E2BIG; + + if (cpuid->nent) { + e2 = vmemdup_user(entries, array_size(sizeof(*e2), cpuid->nent)); + if (IS_ERR(e2)) + return PTR_ERR(e2); + } + + r = kvm_check_cpuid(e2, cpuid->nent); if (r) { - vcpu->arch.cpuid_nent = 0; - goto out; + kvfree(e2); + return r; } + kvfree(vcpu->arch.cpuid_entries); + vcpu->arch.cpuid_entries = e2; + vcpu->arch.cpuid_nent = cpuid->nent; + kvm_update_cpuid_runtime(vcpu); kvm_vcpu_after_set_cpuid(vcpu); -out: - return r; + + return 0; } int kvm_vcpu_ioctl_get_cpuid2(struct kvm_vcpu *vcpu, diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index ca940de53e182..92f85003b4bb4 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -9948,6 +9948,7 @@ void kvm_arch_vcpu_destroy(struct kvm_vcpu *vcpu) kvm_mmu_destroy(vcpu); srcu_read_unlock(&vcpu->kvm->srcu, idx); free_page((unsigned long)vcpu->arch.pio_data); + kvfree(vcpu->arch.cpuid_entries); if (!lapic_in_kernel(vcpu)) static_key_slow_dec(&kvm_no_apic_vcpu); }