KVM: x86: introduce kvm_supported_xcr0()
XSAVE support for KVM is already using host_xcr0 & KVM_SUPPORTED_XCR0 as a "dynamic" version of KVM_SUPPORTED_XCR0. However, this is not enough because the MPX bits should not be presented to the guest unless kvm_x86_ops confirms the support. So, replace all instances of host_xcr0 & KVM_SUPPORTED_XCR0 with a new function kvm_supported_xcr0() that also has this check. Note that here: if (xstate_bv & ~KVM_SUPPORTED_XCR0) return -EINVAL; if (xstate_bv & ~host_cr0) return -EINVAL; the code is equivalent to if ((xstate_bv & ~KVM_SUPPORTED_XCR0) || (xstate_bv & ~host_cr0) return -EINVAL; i.e. "xstate_bv & (~KVM_SUPPORTED_XCR0 | ~host_cr0)" which is in turn equal to "xstate_bv & ~(KVM_SUPPORTED_XCR0 & host_cr0)". So we should also use the new function there. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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94b3ffcd41
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@ -43,6 +43,16 @@ static u32 xstate_required_size(u64 xstate_bv)
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return ret;
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}
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u64 kvm_supported_xcr0(void)
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{
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u64 xcr0 = KVM_SUPPORTED_XCR0 & host_xcr0;
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if (!kvm_x86_ops->mpx_supported || !kvm_x86_ops->mpx_supported())
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xcr0 &= ~(XSTATE_BNDREGS | XSTATE_BNDCSR);
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return xcr0;
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}
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void kvm_update_cpuid(struct kvm_vcpu *vcpu)
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{
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struct kvm_cpuid_entry2 *best;
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@ -73,7 +83,7 @@ void kvm_update_cpuid(struct kvm_vcpu *vcpu)
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} else {
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vcpu->arch.guest_supported_xcr0 =
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(best->eax | ((u64)best->edx << 32)) &
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host_xcr0 & KVM_SUPPORTED_XCR0;
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kvm_supported_xcr0();
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vcpu->arch.guest_xstate_size = best->ebx =
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xstate_required_size(vcpu->arch.xcr0);
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}
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@ -210,13 +220,6 @@ static void do_cpuid_1_ent(struct kvm_cpuid_entry2 *entry, u32 function,
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entry->flags = 0;
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}
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static bool supported_xcr0_bit(unsigned bit)
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{
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u64 mask = ((u64)1 << bit);
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return mask & KVM_SUPPORTED_XCR0 & host_xcr0;
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}
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#define F(x) bit(X86_FEATURE_##x)
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static int __do_cpuid_ent_emulated(struct kvm_cpuid_entry2 *entry,
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@ -439,16 +442,18 @@ static inline int __do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function,
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}
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case 0xd: {
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int idx, i;
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u64 supported = kvm_supported_xcr0();
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entry->eax &= host_xcr0 & KVM_SUPPORTED_XCR0;
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entry->edx &= (host_xcr0 & KVM_SUPPORTED_XCR0) >> 32;
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entry->eax &= supported;
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entry->edx &= supported >> 32;
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entry->flags |= KVM_CPUID_FLAG_SIGNIFCANT_INDEX;
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for (idx = 1, i = 1; idx < 64; ++idx) {
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u64 mask = ((u64)1 << idx);
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if (*nent >= maxnent)
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goto out;
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do_cpuid_1_ent(&entry[i], function, idx);
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if (entry[i].eax == 0 || !supported_xcr0_bit(idx))
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if (entry[i].eax == 0 || !(supported & mask))
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continue;
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entry[i].flags |=
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KVM_CPUID_FLAG_SIGNIFCANT_INDEX;
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@ -3084,9 +3084,7 @@ static int kvm_vcpu_ioctl_x86_set_xsave(struct kvm_vcpu *vcpu,
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* CPUID leaf 0xD, index 0, EDX:EAX. This is for compatibility
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* with old userspace.
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*/
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if (xstate_bv & ~KVM_SUPPORTED_XCR0)
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return -EINVAL;
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if (xstate_bv & ~host_xcr0)
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if (xstate_bv & ~kvm_supported_xcr0())
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return -EINVAL;
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memcpy(&vcpu->arch.guest_fpu.state->xsave,
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guest_xsave->region, vcpu->arch.guest_xstate_size);
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@ -126,6 +126,8 @@ int kvm_write_guest_virt_system(struct x86_emulate_ctxt *ctxt,
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| XSTATE_BNDREGS | XSTATE_BNDCSR)
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extern u64 host_xcr0;
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extern u64 kvm_supported_xcr0(void);
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extern unsigned int min_timer_period_us;
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extern struct static_key kvm_no_apic_vcpu;
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