linux-kernel - [PATCH 2/5] KVM: x86: add support for UMIP

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Date:   Mon, 13 Nov 2017 15:40:28 +0100
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Cc:     rkrcmar@...hat.com
Subject: [PATCH 2/5] KVM: x86: add support for UMIP

Add the CPUID bits, make the CR4.UMIP bit not reserved anymore, and
add UMIP support for instructions that are already emulated by KVM.

Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
---
 arch/x86/include/asm/kvm_host.h | 2 +-
 arch/x86/kvm/cpuid.c            | 4 ++--
 arch/x86/kvm/emulate.c          | 8 ++++++++
 arch/x86/kvm/x86.c              | 3 +++
 4 files changed, 14 insertions(+), 3 deletions(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index c73e493adf07..1b005ccf4d0b 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -86,7 +86,7 @@
 			  | X86_CR4_PGE | X86_CR4_PCE | X86_CR4_OSFXSR | X86_CR4_PCIDE \
 			  | X86_CR4_OSXSAVE | X86_CR4_SMEP | X86_CR4_FSGSBASE \
 			  | X86_CR4_OSXMMEXCPT | X86_CR4_LA57 | X86_CR4_VMXE \
-			  | X86_CR4_SMAP | X86_CR4_PKE))
+			  | X86_CR4_SMAP | X86_CR4_PKE | X86_CR4_UMIP))
 
 #define CR8_RESERVED_BITS (~(unsigned long)X86_CR8_TPR)
 
diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index 0099e10eb045..77fb8732b47b 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -387,8 +387,8 @@ static inline int __do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function,
 
 	/* cpuid 7.0.ecx*/
 	const u32 kvm_cpuid_7_0_ecx_x86_features =
-		F(AVX512VBMI) | F(LA57) | F(PKU) |
-		0 /*OSPKE*/ | F(AVX512_VPOPCNTDQ);
+		F(AVX512VBMI) | F(LA57) | F(PKU) | 0 /*OSPKE*/ |
+		F(AVX512_VPOPCNTDQ) | F(UMIP);
 
 	/* cpuid 7.0.edx*/
 	const u32 kvm_cpuid_7_0_edx_x86_features =
diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index d90cdc77e077..d27339332ac8 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -3725,6 +3725,10 @@ static int emulate_store_desc_ptr(struct x86_emulate_ctxt *ctxt,
 {
 	struct desc_ptr desc_ptr;
 
+	if ((ctxt->ops->get_cr(ctxt, 4) & X86_CR4_UMIP) &&
+	    ctxt->ops->cpl(ctxt) > 0)
+		return emulate_gp(ctxt, 0);
+
 	if (ctxt->mode == X86EMUL_MODE_PROT64)
 		ctxt->op_bytes = 8;
 	get(ctxt, &desc_ptr);
@@ -3784,6 +3788,10 @@ static int em_lidt(struct x86_emulate_ctxt *ctxt)
 
 static int em_smsw(struct x86_emulate_ctxt *ctxt)
 {
+	if ((ctxt->ops->get_cr(ctxt, 4) & X86_CR4_UMIP) &&
+	    ctxt->ops->cpl(ctxt) > 0)
+		return emulate_gp(ctxt, 0);
+
 	if (ctxt->dst.type == OP_MEM)
 		ctxt->dst.bytes = 2;
 	ctxt->dst.val = ctxt->ops->get_cr(ctxt, 0);
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 03869eb7fcd6..cda567aadd28 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -791,6 +791,9 @@ int kvm_set_cr4(struct kvm_vcpu *vcpu, unsigned long cr4)
 	if (!guest_cpuid_has(vcpu, X86_FEATURE_LA57) && (cr4 & X86_CR4_LA57))
 		return 1;
 
+	if (!guest_cpuid_has(vcpu, X86_FEATURE_UMIP) && (cr4 & X86_CR4_UMIP))
+		return 1;
+
 	if (is_long_mode(vcpu)) {
 		if (!(cr4 & X86_CR4_PAE))
 			return 1;
-- 
1.8.3.1