Re: linux-next: manual merge of the kvm-x86 tree with the kvm-fixes tree

[Sean Christopherson <seanjc@google.com>]

On Wed, Sep 30, 2026, Mark Brown wrote:
> Hi all,
> 
> Today's linux-next merge of the kvm-x86 tree got a conflict in:
> 
>   tools/testing/selftests/kvm/x86/nested_x2apic_test.c
> 
> between commits:
> 
>   b630929bcc4c8 ("KVM: selftests: Extend nested x2APIC test to validate disabling x2APIC virt")
>   b0bc51910f039 ("KVM: selftests: Extend nested x2APIC test to validate using eVMCS for vmcs12")
> 
> from the kvm-fixes tree and commits:
> 
>   9b2f8146fcef9 ("KVM: selftests: Extend nested x2APIC test to validate disabling x2APIC virt")
>   a4bab1c12fd52 ("KVM: selftests: Extend nested x2APIC test to validate using eVMCS for vmcs12")

kvm-fixes got force-pushed, which is what's causing the weird conflict.  In a
tree that hasn't refresh from kvm.git, I see:

  a4bab1c12fd528ccaafee00360e07463873404a9 (kvm/master, kvm/HEAD) KVM: selftests: Extend nested x2APIC test to validate using eVMCS for vmcs12
  9b2f8146fcef9faa73f9dc1bad9a8d6c585cfec8 KVM: selftests: Extend nested x2APIC test to validate disabling x2APIC virt

versus the newer version:

  973ea70393e885e540f714904e51bc6cac80e3d7 (kvm/master, kvm/HEAD) KVM: SEV: Do cache maintenance on the source VM *before* clearing SEV state
  8abbc76120a74bfba1851bd97528099d715e45c6 KVM: SEV: Nullify "have run CPUs" mask pointer when freeing it
  b0bc51910f0391fea09c0a1d32352fec2acb2686 KVM: selftests: Extend nested x2APIC test to validate using eVMCS for vmcs12
  b630929bcc4c867c9abc8cd5a0ebee3bb5ce5dcd KVM: selftests: Extend nested x2APIC test to validate disabling x2APIC virt

Ahh, I see the difference.  Paolo fixed up the Author:

  commit 9b2f8146fcef9faa73f9dc1bad9a8d6c585cfec8
  Author:     Paolo Bonzini <pbonzini@redhat.com>
  AuthorDate: Sat Sep 26 02:04:03 2026 -0400
  Commit:     Paolo Bonzini <pbonzini@redhat.com>
  CommitDate: Sat Sep 26 02:22:15 2026 -0400

versus:

  commit b630929bcc4c867c9abc8cd5a0ebee3bb5ce5dcd
  Author:     Sean Christopherson <seanjc@google.com>
  AuthorDate: Sat Sep 26 02:04:03 2026 -0400
  Commit:     Paolo Bonzini <pbonzini@redhat.com>
  CommitDate: Mon Sep 28 17:11:47 2026 -0400

> from the kvm-x86 tree.
> 
> I fixed it up (see below) and can carry the fix as necessary. This
> is now fixed as far as linux-next is concerned, but any non trivial
> conflicts should be mentioned to your upstream maintainer when your tree
> is submitted for merging.  You may also want to consider cooperating
> with the maintainer of the conflicting tree to minimise any particularly
> complex conflicts.
> 
> diff --combined tools/testing/selftests/kvm/x86/nested_x2apic_test.c
> index ce204ce29a9c0,2ae698c9aa1ce..0000000000000
> --- a/tools/testing/selftests/kvm/x86/nested_x2apic_test.c
> +++ b/tools/testing/selftests/kvm/x86/nested_x2apic_test.c
> @@@ -61,57 -61,55 +61,57 @@@ static void l1_vmx_code(struct vmx_page
>   		evmcs_enable();
>   	}
>   
>  -	prepare_for_vmx_operation(vmx);
>  +	GUEST_ASSERT_EQ(prepare_for_vmx_operation(vmx), true);

This resolution will probably break the final selftests build?  kvm-x86/next
moves these asserts into prepare_for_vmx_operation(), load_evmcs(), load_vmcs()
etc.  I.e. kvm-x86/next should "win".

Regardless, I'll rebase kvm-x86/fixes onto the new kvm/master and rebuild kvm-x86/next,
so this should go away.

>   
>   	if (hv_pages) {
>  -		load_evmcs(hv_pages);
>  +		GUEST_ASSERT(load_evmcs(hv_pages));
>   		current_evmcs->hv_enlightenments_control.msr_bitmap = 1;
>   	} else {
>  -		load_vmcs(vmx);
>  +		GUEST_ASSERT(load_vmcs(vmx));
>   	}
>   
>   	prepare_vmcs(vmx, NULL);
> - 	GUEST_ASSERT_EQ(vmwrite(GUEST_RIP, (unsigned long)l2_guest_code), 0);
> + 	vmwrite(GUEST_RIP, (unsigned long)l2_guest_code);
>   
>  -	control = vmread(PIN_BASED_VM_EXEC_CONTROL);
>  +	control = vmreadz(PIN_BASED_VM_EXEC_CONTROL);
>   	control |= PIN_BASED_EXT_INTR_MASK;
>   	vmwrite(PIN_BASED_VM_EXEC_CONTROL, control);
>   
>  -	control = vmread(CPU_BASED_VM_EXEC_CONTROL);
>  +	control = vmreadz(CPU_BASED_VM_EXEC_CONTROL);
>   	control |= CPU_BASED_USE_MSR_BITMAPS | CPU_BASED_TPR_SHADOW;
>  -	vmwrite(CPU_BASED_VM_EXEC_CONTROL, control);
>  +	GUEST_ASSERT_EQ(vmwrite(CPU_BASED_VM_EXEC_CONTROL, control), 0);
>   
>  -	control = vmread(SECONDARY_VM_EXEC_CONTROL);
>  +	control = vmreadz(SECONDARY_VM_EXEC_CONTROL);
>   	control |= SECONDARY_EXEC_VIRTUALIZE_X2APIC_MODE |
>   		   SECONDARY_EXEC_APIC_REGISTER_VIRT |
>   		   SECONDARY_EXEC_VIRTUAL_INTR_DELIVERY;
>   	control &= (rdmsr(MSR_IA32_VMX_PROCBASED_CTLS2) >> 32);
>  -	vmwrite(SECONDARY_VM_EXEC_CONTROL, control);
>  +	GUEST_ASSERT_EQ(vmwrite(SECONDARY_VM_EXEC_CONTROL, control), 0);
>   
>  -	vmlaunch();
>  -	GUEST_ASSERT_EQ(vmread(VM_EXIT_REASON), EXIT_REASON_CPUID);
>  -	vmwrite(GUEST_RIP, vmread(GUEST_RIP) + vmread(VM_EXIT_INSTRUCTION_LEN));
>  +	GUEST_ASSERT(!vmlaunch());
>  +	GUEST_ASSERT_EQ(vmreadz(VM_EXIT_REASON), EXIT_REASON_CPUID);
>  +	GUEST_ASSERT_EQ(vmwrite(GUEST_RIP,
>  +			vmreadz(GUEST_RIP) + vmreadz(VM_EXIT_INSTRUCTION_LEN)), 0);


>   }
>   
>   static void l1_vmx_code_part2(void)
>   {
>   	u64 control;
>   
>  -	control = vmread(CPU_BASED_VM_EXEC_CONTROL);
>  +	control = vmreadz(CPU_BASED_VM_EXEC_CONTROL);
>   	control &= ~CPU_BASED_TPR_SHADOW;
>  -	vmwrite(CPU_BASED_VM_EXEC_CONTROL, control);
>  +	GUEST_ASSERT_EQ(vmwrite(CPU_BASED_VM_EXEC_CONTROL, control), 0);
>   
>  -	control = vmread(SECONDARY_VM_EXEC_CONTROL);
>  +	control = vmreadz(SECONDARY_VM_EXEC_CONTROL);
>   	control &= ~(SECONDARY_EXEC_VIRTUALIZE_X2APIC_MODE |
>   			SECONDARY_EXEC_APIC_REGISTER_VIRT |
>   			SECONDARY_EXEC_VIRTUAL_INTR_DELIVERY);
>  -	vmwrite(SECONDARY_VM_EXEC_CONTROL, control);
>  +	GUEST_ASSERT_EQ(vmwrite(SECONDARY_VM_EXEC_CONTROL, control), 0);
>   
>  -	vmresume();
>  -	GUEST_ASSERT_EQ(vmread(VM_EXIT_REASON), EXIT_REASON_CPUID);
>  -	vmwrite(GUEST_RIP, vmread(GUEST_RIP) + vmread(VM_EXIT_INSTRUCTION_LEN));
>  +	GUEST_ASSERT(!vmresume());
>  +	GUEST_ASSERT_EQ(vmreadz(VM_EXIT_REASON), EXIT_REASON_CPUID);
>  +	GUEST_ASSERT_EQ(vmwrite(GUEST_RIP,
>  +			vmreadz(GUEST_RIP) + vmreadz(VM_EXIT_INSTRUCTION_LEN)), 0);
>   }
>   
>   static void l1_test_x2apic_intercepts(void)