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

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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 d7f0a00e43 ("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: Sean Christopherson <seanjc@google.com>
This commit is contained in:
Sean Christopherson 2024-02-09 14:16:59 -08:00
parent 0c47651403
commit a946607868
5 changed files with 20 additions and 14 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
arch/x86/include/asm/kvm_host.h
View File

@ -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;

1
arch/x86/kvm/kvm_emulate.h
View File

@ -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;
};
/*

14
arch/x86/kvm/mmu/paging_tmpl.h
View File

@ -497,21 +497,21 @@ error:
* 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) <<
EPT_VIOLATION_RWX_SHIFT;
walker->fault.exit_qualification |= (pte_access & VMX_EPT_RWX_MASK) <<
EPT_VIOLATION_RWX_SHIFT;
}
#endif
walker->fault.address = addr;

14
arch/x86/kvm/vmx/nested.c
View File

@ -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;
}

2
arch/x86/kvm/vmx/vmx.c
View File

@ -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