Commit a9466078 authored by Sean Christopherson's avatar Sean Christopherson
Browse files

KVM: x86: Move nEPT exit_qualification field from kvm_vcpu_arch to x86_exception 

Move the exit_qualification field that is used to track information about
in-flight nEPT violations from "struct kvm_vcpu_arch" to "x86_exception",
i.e. associate the information with the actual nEPT violation instead of
the vCPU.  To handle bits that are pulled from vmcs.EXIT_QUALIFICATION,
i.e. that are propagated from the "original" EPT violation VM-Exit, simply
grab them from the VMCS on-demand when injecting a nEPT Violation or a PML
Full VM-exit.

Aside from being ugly, having an exit_qualification field in kvm_vcpu_arch
is outright dangerous, e.g. see commit d7f0a00e ("KVM: VMX: Report
up-to-date exit qualification to userspace").

Opportunstically add a comment to call out that PML Full and EPT Violation
VM-Exits use the same bit to report NMI blocking information.

Link: https://lore.kernel.org/r/20240209221700.393189-3-seanjc@google.com


Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
parent 0c476514

arch/x86/include/asm/kvm_host.h

+0 −3
Original line number Diff line number Diff line
@@ -993,9 +993,6 @@ struct kvm_vcpu_arch { 


	u64 msr_kvm_poll_control;



	/* set at EPT violation at this point */

	unsigned long exit_qualification;



	/* pv related host specific info */

	struct {

		bool pv_unhalted;

arch/x86/kvm/kvm_emulate.h

+1 −0
Original line number Diff line number Diff line
@@ -26,6 +26,7 @@ struct x86_exception { 
	bool nested_page_fault;

	u64 address; /* cr2 or nested page fault gpa */

	u8 async_page_fault;

	unsigned long exit_qualification;

};



/*

arch/x86/kvm/mmu/paging_tmpl.h

+7 −7
Original line number Diff line number Diff line
@@ -497,20 +497,20 @@ static int FNAME(walk_addr_generic)(struct guest_walker *walker, 
	 * The other bits are set to 0.

	 */

	if (!(errcode & PFERR_RSVD_MASK)) {

		vcpu->arch.exit_qualification &= (EPT_VIOLATION_GVA_IS_VALID |

						  EPT_VIOLATION_GVA_TRANSLATED);

		walker->fault.exit_qualification = 0;



		if (write_fault)

			vcpu->arch.exit_qualification |= EPT_VIOLATION_ACC_WRITE;

			walker->fault.exit_qualification |= EPT_VIOLATION_ACC_WRITE;

		if (user_fault)

			vcpu->arch.exit_qualification |= EPT_VIOLATION_ACC_READ;

			walker->fault.exit_qualification |= EPT_VIOLATION_ACC_READ;

		if (fetch_fault)

			vcpu->arch.exit_qualification |= EPT_VIOLATION_ACC_INSTR;

			walker->fault.exit_qualification |= EPT_VIOLATION_ACC_INSTR;



		/*

		 * Note, pte_access holds the raw RWX bits from the EPTE, not

		 * ACC_*_MASK flags!

		 */

		vcpu->arch.exit_qualification |= (pte_access & VMX_EPT_RWX_MASK) <<

		walker->fault.exit_qualification |= (pte_access & VMX_EPT_RWX_MASK) <<

						     EPT_VIOLATION_RWX_SHIFT;

	}

#endif

arch/x86/kvm/vmx/nested.c

+12 −2
Original line number Diff line number Diff line
@@ -409,18 +409,28 @@ static void nested_ept_inject_page_fault(struct kvm_vcpu *vcpu, 
{

	struct vmcs12 *vmcs12 = get_vmcs12(vcpu);

	struct vcpu_vmx *vmx = to_vmx(vcpu);

	unsigned long exit_qualification;

	u32 vm_exit_reason;

	unsigned long exit_qualification = vcpu->arch.exit_qualification;



	if (vmx->nested.pml_full) {

		vm_exit_reason = EXIT_REASON_PML_FULL;

		vmx->nested.pml_full = false;

		exit_qualification &= INTR_INFO_UNBLOCK_NMI;



		/*

		 * PML Full and EPT Violation VM-Exits both use bit 12 to report

		 * "NMI unblocking due to IRET", i.e. the bit can be propagated

		 * as-is from the original EXIT_QUALIFICATION.

		 */

		exit_qualification = vmx_get_exit_qual(vcpu) & INTR_INFO_UNBLOCK_NMI;

	} else {

		if (fault->error_code & PFERR_RSVD_MASK) {

			vm_exit_reason = EXIT_REASON_EPT_MISCONFIG;

			exit_qualification = 0;

		} else {

			exit_qualification = fault->exit_qualification;

			exit_qualification |= vmx_get_exit_qual(vcpu) &

					      (EPT_VIOLATION_GVA_IS_VALID |

					       EPT_VIOLATION_GVA_TRANSLATED);

			vm_exit_reason = EXIT_REASON_EPT_VIOLATION;

		}

arch/x86/kvm/vmx/vmx.c

+0 −2
Original line number Diff line number Diff line
@@ -5768,8 +5768,6 @@ static int handle_ept_violation(struct kvm_vcpu *vcpu) 
	error_code |= (exit_qualification & EPT_VIOLATION_GVA_TRANSLATED) != 0 ?

	       PFERR_GUEST_FINAL_MASK : PFERR_GUEST_PAGE_MASK;



	vcpu->arch.exit_qualification = exit_qualification;



	/*

	 * Check that the GPA doesn't exceed physical memory limits, as that is

	 * a guest page fault.  We have to emulate the instruction here, because