KVM: nVMX: Move host-state field setup to a function

Move the setting of constant host-state fields (fields that do not change
throughout the life of the guest) from vmx_vcpu_setup to a new common function
vmx_set_constant_host_state(). This function will also be used to set the
host state when running L2 guests.
Signed-off-by: Nadav Har'El <nyh@il.ibm.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

arch/x86/kvm/vmx.c

@@ -3394,18 +3394,52 @@ static void vmx_disable_intercept_for_msr(u32 msr, bool longmode_only)
 	__vmx_disable_intercept_for_msr(vmx_msr_bitmap_longmode, msr);
 }
 
+/*
+ * Set up the vmcs's constant host-state fields, i.e., host-state fields that
+ * will not change in the lifetime of the guest.
+ * Note that host-state that does change is set elsewhere. E.g., host-state
+ * that is set differently for each CPU is set in vmx_vcpu_load(), not here.
+ */
+static void vmx_set_constant_host_state(void)
+{
+	u32 low32, high32;
+	unsigned long tmpl;
+	struct desc_ptr dt;
+
+	vmcs_writel(HOST_CR0, read_cr0() | X86_CR0_TS);  /* 22.2.3 */
+	vmcs_writel(HOST_CR4, read_cr4());  /* 22.2.3, 22.2.5 */
+	vmcs_writel(HOST_CR3, read_cr3());  /* 22.2.3  FIXME: shadow tables */
+
+	vmcs_write16(HOST_CS_SELECTOR, __KERNEL_CS);  /* 22.2.4 */
+	vmcs_write16(HOST_DS_SELECTOR, __KERNEL_DS);  /* 22.2.4 */
+	vmcs_write16(HOST_ES_SELECTOR, __KERNEL_DS);  /* 22.2.4 */
+	vmcs_write16(HOST_SS_SELECTOR, __KERNEL_DS);  /* 22.2.4 */
+	vmcs_write16(HOST_TR_SELECTOR, GDT_ENTRY_TSS*8);  /* 22.2.4 */
+
+	native_store_idt(&dt);
+	vmcs_writel(HOST_IDTR_BASE, dt.address);   /* 22.2.4 */
+
+	asm("mov $.Lkvm_vmx_return, %0" : "=r"(tmpl));
+	vmcs_writel(HOST_RIP, tmpl); /* 22.2.5 */
+
+	rdmsr(MSR_IA32_SYSENTER_CS, low32, high32);
+	vmcs_write32(HOST_IA32_SYSENTER_CS, low32);
+	rdmsrl(MSR_IA32_SYSENTER_EIP, tmpl);
+	vmcs_writel(HOST_IA32_SYSENTER_EIP, tmpl);   /* 22.2.3 */
+
+	if (vmcs_config.vmexit_ctrl & VM_EXIT_LOAD_IA32_PAT) {
+		rdmsr(MSR_IA32_CR_PAT, low32, high32);
+		vmcs_write64(HOST_IA32_PAT, low32 | ((u64) high32 << 32));
+	}
+}
+
 /*
  * Sets up the vmcs for emulated real mode.
  */
 static int vmx_vcpu_setup(struct vcpu_vmx *vmx)
 {
-	u32 host_sysenter_cs, msr_low, msr_high;
-	u32 junk;
-	u64 host_pat;
 	unsigned long a;
-	struct desc_ptr dt;
 	int i;
-	unsigned long kvm_vmx_return;
 	u32 exec_control;
 
 	/* I/O */
@@ -3462,16 +3496,9 @@ static int vmx_vcpu_setup(struct vcpu_vmx *vmx)
 	vmcs_write32(PAGE_FAULT_ERROR_CODE_MATCH, !!bypass_guest_pf);
 	vmcs_write32(CR3_TARGET_COUNT, 0);           /* 22.2.1 */
 
-	vmcs_writel(HOST_CR0, read_cr0() | X86_CR0_TS);  /* 22.2.3 */
-	vmcs_writel(HOST_CR4, read_cr4());  /* 22.2.3, 22.2.5 */
-	vmcs_writel(HOST_CR3, read_cr3());  /* 22.2.3  FIXME: shadow tables */
-
-	vmcs_write16(HOST_CS_SELECTOR, __KERNEL_CS);  /* 22.2.4 */
-	vmcs_write16(HOST_DS_SELECTOR, __KERNEL_DS);  /* 22.2.4 */
-	vmcs_write16(HOST_ES_SELECTOR, __KERNEL_DS);  /* 22.2.4 */
 	vmcs_write16(HOST_FS_SELECTOR, 0);            /* 22.2.4 */
 	vmcs_write16(HOST_GS_SELECTOR, 0);            /* 22.2.4 */
-	vmcs_write16(HOST_SS_SELECTOR, __KERNEL_DS);  /* 22.2.4 */
+	vmx_set_constant_host_state();
 #ifdef CONFIG_X86_64
 	rdmsrl(MSR_FS_BASE, a);
 	vmcs_writel(HOST_FS_BASE, a); /* 22.2.4 */
@@ -3482,32 +3509,15 @@ static int vmx_vcpu_setup(struct vcpu_vmx *vmx)
 	vmcs_writel(HOST_GS_BASE, 0); /* 22.2.4 */
 #endif
 
-	vmcs_write16(HOST_TR_SELECTOR, GDT_ENTRY_TSS*8);  /* 22.2.4 */
-
-	native_store_idt(&dt);
-	vmcs_writel(HOST_IDTR_BASE, dt.address);   /* 22.2.4 */
-
-	asm("mov $.Lkvm_vmx_return, %0" : "=r"(kvm_vmx_return));
-	vmcs_writel(HOST_RIP, kvm_vmx_return); /* 22.2.5 */
 	vmcs_write32(VM_EXIT_MSR_STORE_COUNT, 0);
 	vmcs_write32(VM_EXIT_MSR_LOAD_COUNT, 0);
 	vmcs_write64(VM_EXIT_MSR_LOAD_ADDR, __pa(vmx->msr_autoload.host));
 	vmcs_write32(VM_ENTRY_MSR_LOAD_COUNT, 0);
 	vmcs_write64(VM_ENTRY_MSR_LOAD_ADDR, __pa(vmx->msr_autoload.guest));
 
-	rdmsr(MSR_IA32_SYSENTER_CS, host_sysenter_cs, junk);
-	vmcs_write32(HOST_IA32_SYSENTER_CS, host_sysenter_cs);
-	rdmsrl(MSR_IA32_SYSENTER_ESP, a);
-	vmcs_writel(HOST_IA32_SYSENTER_ESP, a);   /* 22.2.3 */
-	rdmsrl(MSR_IA32_SYSENTER_EIP, a);
-	vmcs_writel(HOST_IA32_SYSENTER_EIP, a);   /* 22.2.3 */
-
-	if (vmcs_config.vmexit_ctrl & VM_EXIT_LOAD_IA32_PAT) {
-		rdmsr(MSR_IA32_CR_PAT, msr_low, msr_high);
-		host_pat = msr_low | ((u64) msr_high << 32);
-		vmcs_write64(HOST_IA32_PAT, host_pat);
-	}
 	if (vmcs_config.vmentry_ctrl & VM_ENTRY_LOAD_IA32_PAT) {
+		u32 msr_low, msr_high;
+		u64 host_pat;
 		rdmsr(MSR_IA32_CR_PAT, msr_low, msr_high);
 		host_pat = msr_low | ((u64) msr_high << 32);
 		/* Write the default value follow host pat */