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Commit a7c0b07d authored by Wanpeng Li's avatar Wanpeng Li Committed by Paolo Bonzini
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KVM: nVMX: nested TPR shadow/threshold emulation 

This patch fix bug https://bugzilla.kernel.org/show_bug.cgi?id=61411



TPR shadow/threshold feature is important to speed up the Windows guest.
Besides, it is a must feature for certain VMM.

We map virtual APIC page address and TPR threshold from L1 VMCS. If
TPR_BELOW_THRESHOLD VM exit is triggered by L2 guest and L1 interested
in, we inject it into L1 VMM for handling.

Reviewed-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: default avatarWanpeng Li <wanpeng.li@linux.intel.com>
[Add PAGE_ALIGNED check, do not write useless virtual APIC page address
 if TPR shadowing is disabled. - Paolo]
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent a2bcba50

arch/x86/kvm/vmx.c

+51 −3
Original line number Diff line number Diff line
@@ -397,6 +397,7 @@ struct nested_vmx { 
	 * we must keep them pinned while L2 runs.

	 */

	struct page *apic_access_page;

	struct page *virtual_apic_page;

	u64 msr_ia32_feature_control;



	struct hrtimer preemption_timer;
@@ -555,6 +556,7 @@ static int max_shadow_read_only_fields = 
	ARRAY_SIZE(shadow_read_only_fields);



static unsigned long shadow_read_write_fields[] = {

	TPR_THRESHOLD,

	GUEST_RIP,

	GUEST_RSP,

	GUEST_CR0,
@@ -2352,7 +2354,7 @@ static __init void nested_vmx_setup_ctls_msrs(void) 
		CPU_BASED_MOV_DR_EXITING | CPU_BASED_UNCOND_IO_EXITING |

		CPU_BASED_USE_IO_BITMAPS | CPU_BASED_MONITOR_EXITING |

		CPU_BASED_RDPMC_EXITING | CPU_BASED_RDTSC_EXITING |

		CPU_BASED_PAUSE_EXITING |

		CPU_BASED_PAUSE_EXITING | CPU_BASED_TPR_SHADOW |

		CPU_BASED_ACTIVATE_SECONDARY_CONTROLS;

	/*

	 * We can allow some features even when not supported by the
@@ -6246,6 +6248,10 @@ static void free_nested(struct vcpu_vmx *vmx) 
		nested_release_page(vmx->nested.apic_access_page);

		vmx->nested.apic_access_page = 0;

	}

	if (vmx->nested.virtual_apic_page) {

		nested_release_page(vmx->nested.virtual_apic_page);

		vmx->nested.virtual_apic_page = 0;

	}



	nested_free_all_saved_vmcss(vmx);

}
@@ -7034,7 +7040,7 @@ static bool nested_vmx_exit_handled(struct kvm_vcpu *vcpu) 
	case EXIT_REASON_MCE_DURING_VMENTRY:

		return 0;

	case EXIT_REASON_TPR_BELOW_THRESHOLD:

		return 1;

		return nested_cpu_has(vmcs12, CPU_BASED_TPR_SHADOW);

	case EXIT_REASON_APIC_ACCESS:

		return nested_cpu_has2(vmcs12,

			SECONDARY_EXEC_VIRTUALIZE_APIC_ACCESSES);
@@ -7155,6 +7161,12 @@ static int vmx_handle_exit(struct kvm_vcpu *vcpu) 


static void update_cr8_intercept(struct kvm_vcpu *vcpu, int tpr, int irr)

{

	struct vmcs12 *vmcs12 = get_vmcs12(vcpu);



	if (is_guest_mode(vcpu) &&

		nested_cpu_has(vmcs12, CPU_BASED_TPR_SHADOW))

		return;



	if (irr == -1 || tpr < irr) {

		vmcs_write32(TPR_THRESHOLD, 0);

		return;
@@ -7933,8 +7945,8 @@ static bool nested_get_vmcs12_pages(struct kvm_vcpu *vcpu, 
	struct vcpu_vmx *vmx = to_vmx(vcpu);



	if (nested_cpu_has2(vmcs12, SECONDARY_EXEC_VIRTUALIZE_APIC_ACCESSES)) {

		if (!PAGE_ALIGNED(vmcs12->apic_access_addr))

		/* TODO: Also verify bits beyond physical address width are 0 */

		if (!PAGE_ALIGNED(vmcs12->apic_access_addr))

			return false;



		/*
@@ -7948,6 +7960,31 @@ static bool nested_get_vmcs12_pages(struct kvm_vcpu *vcpu, 
		vmx->nested.apic_access_page =

			nested_get_page(vcpu, vmcs12->apic_access_addr);

	}



	if (nested_cpu_has(vmcs12, CPU_BASED_TPR_SHADOW)) {

		/* TODO: Also verify bits beyond physical address width are 0 */

		if (!PAGE_ALIGNED(vmcs12->virtual_apic_page_addr))

			return false;



		if (vmx->nested.virtual_apic_page) /* shouldn't happen */

			nested_release_page(vmx->nested.virtual_apic_page);

		vmx->nested.virtual_apic_page =

			nested_get_page(vcpu, vmcs12->virtual_apic_page_addr);



		/*

		 * Failing the vm entry is _not_ what the processor does

		 * but it's basically the only possibility we have.

		 * We could still enter the guest if CR8 load exits are

		 * enabled, CR8 store exits are enabled, and virtualize APIC

		 * access is disabled; in this case the processor would never

		 * use the TPR shadow and we could simply clear the bit from

		 * the execution control.  But such a configuration is useless,

		 * so let's keep the code simple.

		 */

		if (!vmx->nested.virtual_apic_page)

			return false;

	}



	return true;

}
@@ -8141,6 +8178,13 @@ static void prepare_vmcs02(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12) 
	exec_control &= ~CPU_BASED_VIRTUAL_NMI_PENDING;

	exec_control &= ~CPU_BASED_TPR_SHADOW;

	exec_control |= vmcs12->cpu_based_vm_exec_control;



	if (exec_control & CPU_BASED_TPR_SHADOW) {

		vmcs_write64(VIRTUAL_APIC_PAGE_ADDR,

				page_to_phys(vmx->nested.virtual_apic_page));

		vmcs_write32(TPR_THRESHOLD, vmcs12->tpr_threshold);

	}



	/*

	 * Merging of IO and MSR bitmaps not currently supported.

	 * Rather, exit every time.
@@ -8908,6 +8952,10 @@ static void nested_vmx_vmexit(struct kvm_vcpu *vcpu, u32 exit_reason, 
		nested_release_page(vmx->nested.apic_access_page);

		vmx->nested.apic_access_page = 0;

	}

	if (vmx->nested.virtual_apic_page) {

		nested_release_page(vmx->nested.virtual_apic_page);

		vmx->nested.virtual_apic_page = 0;

	}



	/*

	 * Exiting from L2 to L1, we're now back to L1 which thinks it just