Messages in this thread Patch in this message | | | From | Yang Zhong <> | Subject | [PATCH 09/19] kvm: x86: Prepare reallocation check | Date | Tue, 7 Dec 2021 19:03:49 -0500 |
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From: Jing Liu <jing2.liu@intel.com>
On native fpstate reallocation is triggered by #NM because IA32_XFD is initialized to 1 for all native tasks.
However #NM in guest is not trapped by KVM. Instead, guest enabling of a dynamic extended feature can be captured via emulation of IA32_XFD and XSETBV. Basically having guest XCR0[i]=1 and XFD[i]=0 indicates that the feature[i] is activated by the guest.
This patch provides a helper function for such check, invoked when either XCR0 or XFD is changed in the emulation path.
Signed-off-by: Jing Liu <jing2.liu@intel.com> Signed-off-by: Kevin Tian <kevin.tian@intel.com> Signed-off-by: Yang Zhong <yang.zhong@intel.com> --- arch/x86/kvm/x86.c | 24 ++++++++++++++++++++++++ arch/x86/kvm/x86.h | 1 + 2 files changed, 25 insertions(+)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 05f2cda73d69..91cc6f69a7ca 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -956,6 +956,30 @@ void kvm_load_host_xsave_state(struct kvm_vcpu *vcpu) } EXPORT_SYMBOL_GPL(kvm_load_host_xsave_state); +bool kvm_check_guest_realloc_fpstate(struct kvm_vcpu *vcpu, u64 xfd) +{ + u64 xcr0 = vcpu->arch.xcr0 & XFEATURE_MASK_USER_DYNAMIC; + + /* For any state which is enabled dynamically */ + if ((xfd & xcr0) != xcr0) { + u64 request = (xcr0 ^ xfd) & xcr0; + struct fpu_guest *guest_fpu = &vcpu->arch.guest_fpu; + + /* + * If requested features haven't been enabled, update + * the request bitmap and tell the caller to request + * dynamic buffer reallocation. + */ + if ((guest_fpu->user_xfeatures & request) != request) { + vcpu->arch.guest_fpu.realloc_request = request; + return true; + } + } + + return false; +} +EXPORT_SYMBOL_GPL(kvm_check_guest_realloc_fpstate); + static int __kvm_set_xcr(struct kvm_vcpu *vcpu, u32 index, u64 xcr) { u64 xcr0 = xcr; diff --git a/arch/x86/kvm/x86.h b/arch/x86/kvm/x86.h index 4abcd8d9836d..24a323980146 100644 --- a/arch/x86/kvm/x86.h +++ b/arch/x86/kvm/x86.h @@ -445,6 +445,7 @@ static inline void kvm_machine_check(void) void kvm_load_guest_xsave_state(struct kvm_vcpu *vcpu); void kvm_load_host_xsave_state(struct kvm_vcpu *vcpu); +bool kvm_check_guest_realloc_fpstate(struct kvm_vcpu *vcpu, u64 new_xfd); int kvm_spec_ctrl_test_value(u64 value); bool kvm_is_valid_cr4(struct kvm_vcpu *vcpu, unsigned long cr4); int kvm_handle_memory_failure(struct kvm_vcpu *vcpu, int r,
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