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Date: Thu, 1 Oct 2020 15:05:39 +0200 From: Vitaly Kuznetsov <vkuznets@...hat.com> To: kvm@...r.kernel.org, Paolo Bonzini <pbonzini@...hat.com> Cc: Sean Christopherson <sean.j.christopherson@...el.com>, Wanpeng Li <wanpengli@...cent.com>, Jim Mattson <jmattson@...gle.com>, "Dr . David Alan Gilbert" <dgilbert@...hat.com>, Wei Huang <whuang2@....com>, linux-kernel@...r.kernel.org Subject: [PATCH 1/3] KVM: x86: disconnect kvm_check_cpuid() from vcpu->arch.cpuid_entries As a preparatory step to allocating vcpu->arch.cpuid_entries dynamically make kvm_check_cpuid() check work with an arbitrary 'struct kvm_cpuid_entry2' array. Currently, when kvm_check_cpuid() fails we reset vcpu->arch.cpuid_nent to 0 and this is kind of weird, i.e. one would expect CPUIDs to remain unchanged when KVM_SET_CPUID[2] call fails. No functional change intended. It would've been possible to move the updated kvm_check_cpuid() in kvm_vcpu_ioctl_set_cpuid2() and check the supplied input before we start updating vcpu->arch.cpuid_entries/nent but we can't do the same in kvm_vcpu_ioctl_set_cpuid() as we'll have to copy 'struct kvm_cpuid_entry' entries first. The change will be made when vcpu->arch.cpuid_entries[] array becomes allocated dynamically. Suggested-by: Sean Christopherson <sean.j.christopherson@...el.com> Signed-off-by: Vitaly Kuznetsov <vkuznets@...hat.com> --- arch/x86/kvm/cpuid.c | 38 +++++++++++++++++++++++--------------- 1 file changed, 23 insertions(+), 15 deletions(-) diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c index 37c3668a774f..529348ddedc1 100644 --- a/arch/x86/kvm/cpuid.c +++ b/arch/x86/kvm/cpuid.c @@ -54,7 +54,24 @@ static u32 xstate_required_size(u64 xstate_bv, bool compacted) #define F feature_bit -static int kvm_check_cpuid(struct kvm_vcpu *vcpu) +static inline struct kvm_cpuid_entry2 *cpuid_entry2_find( + struct kvm_cpuid_entry2 *entries, int nent, u32 function, u32 index) +{ + struct kvm_cpuid_entry2 *e; + int i; + + for (i = 0; i < nent; i++) { + e = &entries[i]; + + if (e->function == function && (e->index == index || + !(e->flags & KVM_CPUID_FLAG_SIGNIFCANT_INDEX))) + return e; + } + + return NULL; +} + +static int kvm_check_cpuid(struct kvm_cpuid_entry2 *entries, int nent) { struct kvm_cpuid_entry2 *best; @@ -62,7 +79,7 @@ static int kvm_check_cpuid(struct kvm_vcpu *vcpu) * The existing code assumes virtual address is 48-bit or 57-bit in the * canonical address checks; exit if it is ever changed. */ - best = kvm_find_cpuid_entry(vcpu, 0x80000008, 0); + best = cpuid_entry2_find(entries, nent, 0x80000008, 0); if (best) { int vaddr_bits = (best->eax & 0xff00) >> 8; @@ -220,7 +237,7 @@ int kvm_vcpu_ioctl_set_cpuid(struct kvm_vcpu *vcpu, vcpu->arch.cpuid_entries[i].padding[2] = 0; } vcpu->arch.cpuid_nent = cpuid->nent; - r = kvm_check_cpuid(vcpu); + r = kvm_check_cpuid(vcpu->arch.cpuid_entries, cpuid->nent); if (r) { vcpu->arch.cpuid_nent = 0; kvfree(cpuid_entries); @@ -250,7 +267,7 @@ int kvm_vcpu_ioctl_set_cpuid2(struct kvm_vcpu *vcpu, cpuid->nent * sizeof(struct kvm_cpuid_entry2))) goto out; vcpu->arch.cpuid_nent = cpuid->nent; - r = kvm_check_cpuid(vcpu); + r = kvm_check_cpuid(vcpu->arch.cpuid_entries, cpuid->nent); if (r) { vcpu->arch.cpuid_nent = 0; goto out; @@ -940,17 +957,8 @@ int kvm_dev_ioctl_get_cpuid(struct kvm_cpuid2 *cpuid, struct kvm_cpuid_entry2 *kvm_find_cpuid_entry(struct kvm_vcpu *vcpu, u32 function, u32 index) { - struct kvm_cpuid_entry2 *e; - int i; - - for (i = 0; i < vcpu->arch.cpuid_nent; ++i) { - e = &vcpu->arch.cpuid_entries[i]; - - if (e->function == function && (e->index == index || - !(e->flags & KVM_CPUID_FLAG_SIGNIFCANT_INDEX))) - return e; - } - return NULL; + return cpuid_entry2_find(vcpu->arch.cpuid_entries, vcpu->arch.cpuid_nent, + function, index); } EXPORT_SYMBOL_GPL(kvm_find_cpuid_entry); -- 2.25.4
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