linux-kernel - [PATCH 11/19] kvm: x86: Check fpstate reallocation in XSETBV emulation

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Date:   Tue,  7 Dec 2021 19:03:51 -0500
From:   Yang Zhong <yang.zhong@...el.com>
To:     x86@...nel.org, kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
        tglx@...utronix.de, mingo@...hat.com, bp@...en8.de,
        dave.hansen@...ux.intel.com, pbonzini@...hat.com
Cc:     seanjc@...gle.com, jun.nakajima@...el.com, kevin.tian@...el.com,
        jing2.liu@...ux.intel.com, jing2.liu@...el.com,
        yang.zhong@...el.com
Subject: [PATCH 11/19] kvm: x86: Check fpstate reallocation in XSETBV emulation

XSETBV allows the software to write the extended control register
XCR0, thus its emulation handler also needs to check fpstate
reallocation when the changed XCR0 value enables certain
dynamically-enabled features.

Signed-off-by: Jing Liu <jing2.liu@...el.com>
Signed-off-by: Yang Zhong <yang.zhong@...el.com>
---
 arch/x86/kvm/x86.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index c83887cb55ee..b195f4fa888f 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1028,6 +1028,15 @@ int kvm_emulate_xsetbv(struct kvm_vcpu *vcpu)
 		return 1;
 	}
 
+	if (guest_cpuid_has(vcpu, X86_FEATURE_XFD)) {
+		if (kvm_check_guest_realloc_fpstate(vcpu, vcpu->arch.guest_fpu.fpstate->xfd)) {
+			vcpu->run->exit_reason = KVM_EXIT_FPU_REALLOC;
+			vcpu->arch.complete_userspace_io =
+				kvm_skip_emulated_instruction;
+			return 0;
+		}
+	}
+
 	return kvm_skip_emulated_instruction(vcpu);
 }
 EXPORT_SYMBOL_GPL(kvm_emulate_xsetbv);