linux-kernel - [PATCH v2] KVM: nVMX: expose INS/OUTS information support

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Date:   Mon,  5 Sep 2016 17:47:59 +0300
From:   Jan Dakinevich <jan.dakinevich@...il.com>
To:     kvm@...r.kernel.org
Cc:     pbonzini@...hat.com, rkrcmar@...hat.com,
        linux-kernel@...r.kernel.org, ynorov@...iumnetworks.com,
        Jan Dakinevich <jan.dakinevich@...il.com>
Subject: [PATCH v2] KVM: nVMX: expose INS/OUTS information support

Expose the feature to L1 hypervisor if host CPU supports it, since
certain hypervisors requires it for own purposes.

According to Intel SDM A.1, if CPU supports the feature,
VMX_INSTRUCTION_INFO field of VMCS will contain detailed information
about INS/OUTS instructions handling. This field is already copied to
VMCS12 for L1 hypervisor (see prepare_vmcs12 routine) independently of
feature presence.

Signed-off-by: Jan Dakinevich <jan.dakinevich@...il.com>
---
v1:
 * don't copy to basic_cap bits, which are already copied to size field
 * fix commit message

 arch/x86/kvm/vmx.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index a4bb2bd..10f9fb5 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -939,6 +939,7 @@ static DEFINE_SPINLOCK(vmx_vpid_lock);
 static struct vmcs_config {
 	int size;
 	int order;
+	u32 basic_cap;
 	u32 revision_id;
 	u32 pin_based_exec_ctrl;
 	u32 cpu_based_exec_ctrl;
@@ -1215,6 +1216,11 @@ static inline bool cpu_has_vmx_ple(void)
 		SECONDARY_EXEC_PAUSE_LOOP_EXITING;
 }
 
+static inline bool cpu_has_vmx_basic_inout(void)
+{
+	return	(((u64)vmcs_config.basic_cap << 32) & VMX_BASIC_INOUT);
+}
+
 static inline bool cpu_need_virtualize_apic_accesses(struct kvm_vcpu *vcpu)
 {
 	return flexpriority_enabled && lapic_in_kernel(vcpu);
@@ -2877,6 +2883,8 @@ static int vmx_get_vmx_msr(struct kvm_vcpu *vcpu, u32 msr_index, u64 *pdata)
 		*pdata = VMCS12_REVISION | VMX_BASIC_TRUE_CTLS |
 			   ((u64)VMCS12_SIZE << VMX_BASIC_VMCS_SIZE_SHIFT) |
 			   (VMX_BASIC_MEM_TYPE_WB << VMX_BASIC_MEM_TYPE_SHIFT);
+		if (cpu_has_vmx_basic_inout())
+			*pdata |= VMX_BASIC_INOUT;
 		break;
 	case MSR_IA32_VMX_TRUE_PINBASED_CTLS:
 	case MSR_IA32_VMX_PINBASED_CTLS:
@@ -3458,6 +3466,7 @@ static __init int setup_vmcs_config(struct vmcs_config *vmcs_conf)
 
 	vmcs_conf->size = vmx_msr_high & 0x1fff;
 	vmcs_conf->order = get_order(vmcs_config.size);
+	vmcs_conf->basic_cap = vmx_msr_high & ~0x1fff;
 	vmcs_conf->revision_id = vmx_msr_low;
 
 	vmcs_conf->pin_based_exec_ctrl = _pin_based_exec_control;
-- 
1.9.1