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Commit abc4fc58 authored by Abel Gordon's avatar Abel Gordon Committed by Gleb Natapov
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KVM: nVMX: Detect shadow-vmcs capability 



Add logic required to detect if shadow-vmcs is supported by the
processor. Introduce a new kernel module parameter to specify if L0 should use
shadow vmcs (or not) to run L1.

Signed-off-by: default avatarAbel Gordon <abelg@il.ibm.com>
Reviewed-by: default avatarOrit Wasserman <owasserm@redhat.com>
Signed-off-by: default avatarGleb Natapov <gleb@redhat.com>
parent 89662e56

arch/x86/kvm/vmx.c

+24 −1
Original line number Diff line number Diff line
@@ -87,6 +87,8 @@ module_param(fasteoi, bool, S_IRUGO); 
static bool __read_mostly enable_apicv = 1;

module_param(enable_apicv, bool, S_IRUGO);



static bool __read_mostly enable_shadow_vmcs = 1;

module_param_named(enable_shadow_vmcs, enable_shadow_vmcs, bool, S_IRUGO);

/*

 * If nested=1, nested virtualization is supported, i.e., guests may use

 * VMX and be a hypervisor for its own guests. If nested=0, guests may not
@@ -940,6 +942,18 @@ static inline bool cpu_has_vmx_wbinvd_exit(void) 
		SECONDARY_EXEC_WBINVD_EXITING;

}



static inline bool cpu_has_vmx_shadow_vmcs(void)

{

	u64 vmx_msr;

	rdmsrl(MSR_IA32_VMX_MISC, vmx_msr);

	/* check if the cpu supports writing r/o exit information fields */

	if (!(vmx_msr & MSR_IA32_VMX_MISC_VMWRITE_SHADOW_RO_FIELDS))

		return false;



	return vmcs_config.cpu_based_2nd_exec_ctrl &

		SECONDARY_EXEC_SHADOW_VMCS;

}



static inline bool report_flexpriority(void)

{

	return flexpriority_enabled;
@@ -2632,7 +2646,8 @@ static __init int setup_vmcs_config(struct vmcs_config *vmcs_conf) 
			SECONDARY_EXEC_RDTSCP |

			SECONDARY_EXEC_ENABLE_INVPCID |

			SECONDARY_EXEC_APIC_REGISTER_VIRT |

			SECONDARY_EXEC_VIRTUAL_INTR_DELIVERY;

			SECONDARY_EXEC_VIRTUAL_INTR_DELIVERY |

			SECONDARY_EXEC_SHADOW_VMCS;

		if (adjust_vmx_controls(min2, opt2,

					MSR_IA32_VMX_PROCBASED_CTLS2,

					&_cpu_based_2nd_exec_control) < 0)
@@ -2833,6 +2848,8 @@ static __init int hardware_setup(void) 


	if (!cpu_has_vmx_vpid())

		enable_vpid = 0;

	if (!cpu_has_vmx_shadow_vmcs())

		enable_shadow_vmcs = 0;



	if (!cpu_has_vmx_ept() ||

	    !cpu_has_vmx_ept_4levels()) {
@@ -4077,6 +4094,12 @@ static u32 vmx_secondary_exec_control(struct vcpu_vmx *vmx) 
		exec_control &= ~(SECONDARY_EXEC_APIC_REGISTER_VIRT |

				  SECONDARY_EXEC_VIRTUAL_INTR_DELIVERY);

	exec_control &= ~SECONDARY_EXEC_VIRTUALIZE_X2APIC_MODE;

	/* SECONDARY_EXEC_SHADOW_VMCS is enabled when L1 executes VMPTRLD

	   (handle_vmptrld).

	   We can NOT enable shadow_vmcs here because we don't have yet

	   a current VMCS12

	*/

	exec_control &= ~SECONDARY_EXEC_SHADOW_VMCS;

	return exec_control;

}