On Thursday, 2021-02-18 at 12:54:52 +01, Paolo Bonzini wrote:
> On 18/02/21 11:04, David Edmondson wrote:
>> When dumping the VMCS, retrieve the current guest value of EFER from
>> the kvm_vcpu structure if neither VM_EXIT_SAVE_IA32_EFER or
>> VM_ENTRY_LOAD_IA32_EFER is set, which can occur if the processor does
>> not support the relevant VM-exit/entry controls.
>
> Printing vcpu->arch.efer is not the best choice however. Could we dump
> the whole MSR load/store area instead?
I'm happy to do that, and think that it would be useful, but it won't
help with the original problem (which I should have explained more).
If the guest has EFER_LMA set but we aren't using the entry/exit
controls, vm_read64(GUEST_IA32_EFER) returns 0, causing dump_vmcs() to
erroneously dump the PDPTRs.
> Paolo
>
>> Fixes: 4eb64dce8d0a ("KVM: x86: dump VMCS on invalid entry")
>> Signed-off-by: David Edmondson <david.edmondson@xxxxxxxxxx>
>> ---
>> arch/x86/kvm/vmx/vmx.c | 14 +++++++++-----
>> arch/x86/kvm/vmx/vmx.h | 2 +-
>> 2 files changed, 10 insertions(+), 6 deletions(-)
>>
>> diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
>> index eb69fef57485..74ea4fe6f35e 100644
>> --- a/arch/x86/kvm/vmx/vmx.c
>> +++ b/arch/x86/kvm/vmx/vmx.c
>> @@ -5754,7 +5754,7 @@ static void vmx_dump_dtsel(char *name, uint32_t limit)
>> vmcs_readl(limit + GUEST_GDTR_BASE - GUEST_GDTR_LIMIT));
>> }
>>
>> -void dump_vmcs(void)
>> +void dump_vmcs(struct kvm_vcpu *vcpu)
>> {
>> u32 vmentry_ctl, vmexit_ctl;
>> u32 cpu_based_exec_ctrl, pin_based_exec_ctrl, secondary_exec_control;
>> @@ -5771,7 +5771,11 @@ void dump_vmcs(void)
>> cpu_based_exec_ctrl = vmcs_read32(CPU_BASED_VM_EXEC_CONTROL);
>> pin_based_exec_ctrl = vmcs_read32(PIN_BASED_VM_EXEC_CONTROL);
>> cr4 = vmcs_readl(GUEST_CR4);
>> - efer = vmcs_read64(GUEST_IA32_EFER);
>> + if ((vmexit_ctl & VM_EXIT_SAVE_IA32_EFER) ||
>> + (vmentry_ctl & VM_ENTRY_LOAD_IA32_EFER))
>> + efer = vmcs_read64(GUEST_IA32_EFER);
>> + else
>> + efer = vcpu->arch.efer;
>> secondary_exec_control = 0;
>> if (cpu_has_secondary_exec_ctrls())
>> secondary_exec_control = vmcs_read32(SECONDARY_VM_EXEC_CONTROL);
>> @@ -5955,7 +5959,7 @@ static int vmx_handle_exit(struct kvm_vcpu *vcpu, fastpath_t exit_fastpath)
>> }
>>
>> if (exit_reason & VMX_EXIT_REASONS_FAILED_VMENTRY) {
>> - dump_vmcs();
>> + dump_vmcs(vcpu);
>> vcpu->run->exit_reason = KVM_EXIT_FAIL_ENTRY;
>> vcpu->run->fail_entry.hardware_entry_failure_reason
>> = exit_reason;
>> @@ -5964,7 +5968,7 @@ static int vmx_handle_exit(struct kvm_vcpu *vcpu, fastpath_t exit_fastpath)
>> }
>>
>> if (unlikely(vmx->fail)) {
>> - dump_vmcs();
>> + dump_vmcs(vcpu);
>> vcpu->run->exit_reason = KVM_EXIT_FAIL_ENTRY;
>> vcpu->run->fail_entry.hardware_entry_failure_reason
>> = vmcs_read32(VM_INSTRUCTION_ERROR);
>> @@ -6049,7 +6053,7 @@ static int vmx_handle_exit(struct kvm_vcpu *vcpu, fastpath_t exit_fastpath)
>>
>> unexpected_vmexit:
>> vcpu_unimpl(vcpu, "vmx: unexpected exit reason 0x%x\n", exit_reason);
>> - dump_vmcs();
>> + dump_vmcs(vcpu);
>> vcpu->run->exit_reason = KVM_EXIT_INTERNAL_ERROR;
>> vcpu->run->internal.suberror =
>> KVM_INTERNAL_ERROR_UNEXPECTED_EXIT_REASON;
>> diff --git a/arch/x86/kvm/vmx/vmx.h b/arch/x86/kvm/vmx/vmx.h
>> index 9d3a557949ac..f8a0ce74798e 100644
>> --- a/arch/x86/kvm/vmx/vmx.h
>> +++ b/arch/x86/kvm/vmx/vmx.h
>> @@ -489,6 +489,6 @@ static inline bool vmx_guest_state_valid(struct kvm_vcpu *vcpu)
>> return is_unrestricted_guest(vcpu) || __vmx_guest_state_valid(vcpu);
>> }
>>
>> -void dump_vmcs(void);
>> +void dump_vmcs(struct kvm_vcpu *vcpu);
>>
>> #endif /* __KVM_X86_VMX_H */
>>
dme.
--
Why stay in college? Why go to night school?
