From 4ff417320c2dfc984ec1939a7da888976441a881 Mon Sep 17 00:00:00 2001 From: Paolo Bonzini Date: Mon, 24 Feb 2014 12:15:16 +0100 Subject: [PATCH] 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 --- arch/x86/kvm/cpuid.c | 27 ++++++++++++++++----------- arch/x86/kvm/x86.c | 4 +--- arch/x86/kvm/x86.h | 2 ++ 3 files changed, 19 insertions(+), 14 deletions(-) diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c index ddc8a7e165df..18aefb4d0927 100644 --- a/arch/x86/kvm/cpuid.c +++ b/arch/x86/kvm/cpuid.c @@ -43,6 +43,16 @@ static u32 xstate_required_size(u64 xstate_bv) return ret; } +u64 kvm_supported_xcr0(void) +{ + u64 xcr0 = KVM_SUPPORTED_XCR0 & host_xcr0; + + if (!kvm_x86_ops->mpx_supported || !kvm_x86_ops->mpx_supported()) + xcr0 &= ~(XSTATE_BNDREGS | XSTATE_BNDCSR); + + return xcr0; +} + void kvm_update_cpuid(struct kvm_vcpu *vcpu) { struct kvm_cpuid_entry2 *best; @@ -73,7 +83,7 @@ void kvm_update_cpuid(struct kvm_vcpu *vcpu) } else { vcpu->arch.guest_supported_xcr0 = (best->eax | ((u64)best->edx << 32)) & - host_xcr0 & KVM_SUPPORTED_XCR0; + kvm_supported_xcr0(); vcpu->arch.guest_xstate_size = best->ebx = xstate_required_size(vcpu->arch.xcr0); } @@ -210,13 +220,6 @@ static void do_cpuid_1_ent(struct kvm_cpuid_entry2 *entry, u32 function, entry->flags = 0; } -static bool supported_xcr0_bit(unsigned bit) -{ - u64 mask = ((u64)1 << bit); - - return mask & KVM_SUPPORTED_XCR0 & host_xcr0; -} - #define F(x) bit(X86_FEATURE_##x) static int __do_cpuid_ent_emulated(struct kvm_cpuid_entry2 *entry, @@ -439,16 +442,18 @@ static inline int __do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function, } case 0xd: { int idx, i; + u64 supported = kvm_supported_xcr0(); - entry->eax &= host_xcr0 & KVM_SUPPORTED_XCR0; - entry->edx &= (host_xcr0 & KVM_SUPPORTED_XCR0) >> 32; + entry->eax &= supported; + entry->edx &= supported >> 32; entry->flags |= KVM_CPUID_FLAG_SIGNIFCANT_INDEX; for (idx = 1, i = 1; idx < 64; ++idx) { + u64 mask = ((u64)1 << idx); if (*nent >= maxnent) goto out; do_cpuid_1_ent(&entry[i], function, idx); - if (entry[i].eax == 0 || !supported_xcr0_bit(idx)) + if (entry[i].eax == 0 || !(supported & mask)) continue; entry[i].flags |= KVM_CPUID_FLAG_SIGNIFCANT_INDEX; diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index a37da6b0165a..3f5fb4535f9c 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -3084,9 +3084,7 @@ static int kvm_vcpu_ioctl_x86_set_xsave(struct kvm_vcpu *vcpu, * CPUID leaf 0xD, index 0, EDX:EAX. This is for compatibility * with old userspace. */ - if (xstate_bv & ~KVM_SUPPORTED_XCR0) - return -EINVAL; - if (xstate_bv & ~host_xcr0) + if (xstate_bv & ~kvm_supported_xcr0()) return -EINVAL; memcpy(&vcpu->arch.guest_fpu.state->xsave, guest_xsave->region, vcpu->arch.guest_xstate_size); diff --git a/arch/x86/kvm/x86.h b/arch/x86/kvm/x86.h index 392ecbff0030..8c97bac9a895 100644 --- a/arch/x86/kvm/x86.h +++ b/arch/x86/kvm/x86.h @@ -126,6 +126,8 @@ int kvm_write_guest_virt_system(struct x86_emulate_ctxt *ctxt, | XSTATE_BNDREGS | XSTATE_BNDCSR) extern u64 host_xcr0; +extern u64 kvm_supported_xcr0(void); + extern unsigned int min_timer_period_us; extern struct static_key kvm_no_apic_vcpu; -- 2.20.1