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KVM: VMX: Always reflect SGX EPCM #PFs back into the guest

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When handling intercepted #PFs, reflect EPCM (Enclave Page Cache Map)
violations, i.e. #PFs with the SGX flag set, back into the guest.  KVM
doesn't shadow EPCM entries (the EPCM deals only with virtual/linear
addresses), and so EPCM violation cannot be due to KVM interference,
and more importantly can't be resolved by KVM.

On pre-SGX2 hardware, EPCM violations are delivered as #GP(0) faults, but
on SGX2+ hardware, they are delivered as #PF(SGX).  Failure to account for
the SGX2 behavior could put a vCPU into an infinite loop due to KVM not
realizing the #PF is the guest's responsibility.

Take care to deliver the EPCM violation as a #GP(0) if the _guest_ CPU
model is only SGX1.

Fixes: 72add915fb ("KVM: VMX: Enable SGX virtualization for SGX1, SGX2 and LC")
Cc: Kai Huang <kai.huang@intel.com>
Reviewed-by: Richard Lyu <richard.lyu@suse.com>
Reviewed-by: Kai Huang <kai.huang@intel.com>
Link: https://patch.msgid.link/20251121222018.348987-1-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
This commit is contained in:
Sean Christopherson 2025-11-21 14:20:18 -08:00
parent 9ace4753a5
commit ff8071eb3a
1 changed files with 44 additions and 14 deletions
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58
arch/x86/kvm/vmx/vmx.c
View File

@ -5303,12 +5303,53 @@ static bool is_xfd_nm_fault(struct kvm_vcpu *vcpu)
!kvm_is_cr0_bit_set(vcpu, X86_CR0_TS);
}
static int vmx_handle_page_fault(struct kvm_vcpu *vcpu, u32 error_code)
{
unsigned long cr2 = vmx_get_exit_qual(vcpu);
if (vcpu->arch.apf.host_apf_flags)
goto handle_pf;
/* When using EPT, KVM intercepts #PF only to detect illegal GPAs. */
WARN_ON_ONCE(enable_ept && !allow_smaller_maxphyaddr);
/*
* On SGX2 hardware, EPCM violations are delivered as #PF with the SGX
* flag set in the error code (SGX1 hardware generates #GP(0)). EPCM
* violations have nothing to do with shadow paging and can never be
* resolved by KVM; always reflect them into the guest.
*/
if (error_code & PFERR_SGX_MASK) {
WARN_ON_ONCE(!IS_ENABLED(CONFIG_X86_SGX_KVM) ||
!cpu_feature_enabled(X86_FEATURE_SGX2));
if (guest_cpu_cap_has(vcpu, X86_FEATURE_SGX2))
kvm_fixup_and_inject_pf_error(vcpu, cr2, error_code);
else
kvm_inject_gp(vcpu, 0);
return 1;
}
/*
* If EPT is enabled, fixup and inject the #PF. KVM intercepts #PFs
* only to set PFERR_RSVD as appropriate (hardware won't set RSVD due
* to the GPA being legal with respect to host.MAXPHYADDR).
*/
if (enable_ept) {
kvm_fixup_and_inject_pf_error(vcpu, cr2, error_code);
return 1;
}
handle_pf:
return kvm_handle_page_fault(vcpu, error_code, cr2, NULL, 0);
}
static int handle_exception_nmi(struct kvm_vcpu *vcpu)
{
struct vcpu_vmx *vmx = to_vmx(vcpu);
struct kvm_run *kvm_run = vcpu->run;
u32 intr_info, ex_no, error_code;
unsigned long cr2, dr6;
unsigned long dr6;
u32 vect_info;
vect_info = vmx->idt_vectoring_info;
@ -5383,19 +5424,8 @@ static int handle_exception_nmi(struct kvm_vcpu *vcpu)
return 0;
}
if (is_page_fault(intr_info)) {
cr2 = vmx_get_exit_qual(vcpu);
if (enable_ept && !vcpu->arch.apf.host_apf_flags) {
/*
* EPT will cause page fault only if we need to
* detect illegal GPAs.
*/
WARN_ON_ONCE(!allow_smaller_maxphyaddr);
kvm_fixup_and_inject_pf_error(vcpu, cr2, error_code);
return 1;
} else
return kvm_handle_page_fault(vcpu, error_code, cr2, NULL, 0);
}
if (is_page_fault(intr_info))
return vmx_handle_page_fault(vcpu, error_code);
ex_no = intr_info & INTR_INFO_VECTOR_MASK;