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

From: Stephen Rothwell <[email-masked]>
Date: Thu, 4 Dec 2025 16:10:58 +1100

Hi all,

On Tue, 25 Nov 2025 15:59:53 +1100 Stephen Rothwell <[email-masked]> wrote:
>
> Today's linux-next merge of the kvm-x86 tree got a conflict in:
> 
>   arch/x86/include/asm/cpufeatures.h
> 
> between commits:
> 
>   6ffdb49101f0 ("x86/cpufeatures: Add X86_FEATURE_SGX_EUPDATESVN feature flag")
>   3767def18f4c ("x86/cpufeatures: Add support for L3 Smart Data Cache Injection Allocation Enforcement")
> 
> from the tip tree and commits:
> 
>   5d0316e25def ("x86/cpufeatures: Add X86_FEATURE_X2AVIC_EXT")
>   f6106d41ec84 ("x86/bugs: Use an x86 feature to track the MMIO Stale Data mitigation")
> 
> 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.
> 
> -- 
> Cheers,
> Stephen Rothwell
> 
> diff --cc arch/x86/include/asm/cpufeatures.h
> index d90ce601917c,646d2a77a2e2..000000000000
> --- a/arch/x86/include/asm/cpufeatures.h
> +++ b/arch/x86/include/asm/cpufeatures.h
> @@@ -503,9 -500,12 +504,15 @@@
>   #define X86_FEATURE_IBPB_EXIT_TO_USER	(21*32+14) /* Use IBPB on exit-to-userspace, see VMSCAPE bug */
>   #define X86_FEATURE_ABMC		(21*32+15) /* Assignable Bandwidth Monitoring Counters */
>   #define X86_FEATURE_MSR_IMM		(21*32+16) /* MSR immediate form instructions */
>  -#define X86_FEATURE_X2AVIC_EXT		(21*32+17) /* AMD SVM x2AVIC support for 4k vCPUs */
>  -#define X86_FEATURE_CLEAR_CPU_BUF_VM_MMIO (21*32+18) /*
>  +#define X86_FEATURE_SGX_EUPDATESVN	(21*32+17) /* Support for ENCLS[EUPDATESVN] instruction */
>  +
>  +#define X86_FEATURE_SDCIAE		(21*32+18) /* L3 Smart Data Cache Injection Allocation Enforcement */
> ++#define X86_FEATURE_X2AVIC_EXT		(21*32+19) /* AMD SVM x2AVIC support for 4k vCPUs */
> ++#define X86_FEATURE_CLEAR_CPU_BUF_VM_MMIO (21*32+20) /*
> + 						      * Clear CPU buffers before VM-Enter if the vCPU
> + 						      * can access host MMIO (ignored for all intents
> + 						      * and purposes if CLEAR_CPU_BUF_VM is set).
> + 						      */
>   
>   /*
>    * BUG word(s)

This is now a conflict between the kvm tree and Linus' tree.

-- 
Cheers,
Stephen Rothwell