Re: [PATCH v3 16/16] x86/paravirt: Use alternatives for MSR access with paravirt

From: Juergen Gross

Date: Wed Feb 18 2026 - 10:49:22 EST

On 18.02.26 14:49, kernel test robot wrote:

Hi Juergen,

kernel test robot noticed the following build errors:

[auto build test ERROR on linus/master]
[also build test ERROR on next-20260217]
[cannot apply to tip/x86/core kvm/queue kvm/next kvm/linux-next tip/x86/tdx v6.19]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url: https://github.com/intel-lab-lkp/linux/commits/Juergen-Gross/x86-alternative-Support-alt_replace_call-with-instructions-after-call/20260218-163031
base: linus/master
patch link: https://lore.kernel.org/r/20260218082133.400602-17-jgross%40suse.com
patch subject: [PATCH v3 16/16] x86/paravirt: Use alternatives for MSR access with paravirt
config: x86_64-randconfig-001-20260218 (https://download.01.org/0day-ci/archive/20260218/202602182111.84MpXRx4-lkp@xxxxxxxxx/config)
compiler: clang version 20.1.8 (https://github.com/llvm/llvm-project 87f0227cb60147a26a1eeb4fb06e3b505e9c7261)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260218/202602182111.84MpXRx4-lkp@xxxxxxxxx/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@xxxxxxxxx>
| Closes: https://lore.kernel.org/oe-kbuild-all/202602182111.84MpXRx4-lkp@xxxxxxxxx/

All errors (new ones prefixed by >>):

In file included from arch/x86/kernel/asm-offsets.c:9:
In file included from include/linux/crypto.h:18:
In file included from include/linux/slab.h:17:
In file included from include/linux/gfp.h:7:
In file included from include/linux/mmzone.h:22:
In file included from include/linux/mm_types.h:16:
In file included from include/linux/uprobes.h:18:
In file included from include/linux/timer.h:6:
In file included from include/linux/ktime.h:25:
In file included from include/linux/jiffies.h:10:
In file included from include/linux/time.h:60:
In file included from include/linux/time32.h:13:
In file included from include/linux/timex.h:67:
In file included from arch/x86/include/asm/timex.h:6:
In file included from arch/x86/include/asm/tsc.h:11:
In file included from arch/x86/include/asm/msr.h:300:

arch/x86/include/asm/paravirt-msr.h:114:23: error: unsupported inline asm: input with type 'u64' (aka 'unsigned long long') matching output with type 'int'

114 | PV_WRMSR_CONST(msr, val, EX_TYPE_WRMSR, write_msr, err);
| ^~~ ~~~
arch/x86/include/asm/paravirt-msr.h:91:16: note: expanded from macro 'PV_WRMSR_CONST'
89 | : [err] "=a" (__err), "=d" (rdx), ASM_CALL_CONSTRAINT \
| ~~~~~
90 | : paravirt_ptr(pv_ops_msr, __func), \
91 | [val] "0" (__val), "1" ((__val) >> 32), \
| ^~~~~
arch/x86/include/asm/paravirt-msr.h:116:21: error: unsupported inline asm: input with type 'u64' (aka 'unsigned long long') matching output with type 'int'
116 | PV_WRMSR_VAR(msr, val, EX_TYPE_WRMSR, write_msr, err);
| ^~~ ~~~
arch/x86/include/asm/paravirt-msr.h:73:10: note: expanded from macro 'PV_WRMSR_VAR'
71 | : [err] "=a" (__err), "=d" (rdx), ASM_CALL_CONSTRAINT \
| ~~~~~
72 | : paravirt_ptr(pv_ops_msr, __func), \
73 | "0" (__val), "1" ((__val) >> 32), "c" (__msr) \
| ^~~~~
arch/x86/include/asm/paravirt-msr.h:136:23: error: unsupported inline asm: input with type 'u64' (aka 'unsigned long long') matching output with type 'int'
136 | PV_WRMSR_CONST(msr, val, EX_TYPE_WRMSR_SAFE, write_msr_safe, err);
| ^~~ ~~~
arch/x86/include/asm/paravirt-msr.h:91:16: note: expanded from macro 'PV_WRMSR_CONST'
89 | : [err] "=a" (__err), "=d" (rdx), ASM_CALL_CONSTRAINT \
| ~~~~~
90 | : paravirt_ptr(pv_ops_msr, __func), \
91 | [val] "0" (__val), "1" ((__val) >> 32), \
| ^~~~~
arch/x86/include/asm/paravirt-msr.h:138:21: error: unsupported inline asm: input with type 'u64' (aka 'unsigned long long') matching output with type 'int'
138 | PV_WRMSR_VAR(msr, val, EX_TYPE_WRMSR_SAFE, write_msr_safe, err);
| ^~~ ~~~
arch/x86/include/asm/paravirt-msr.h:73:10: note: expanded from macro 'PV_WRMSR_VAR'
71 | : [err] "=a" (__err), "=d" (rdx), ASM_CALL_CONSTRAINT \
| ~~~~~
72 | : paravirt_ptr(pv_ops_msr, __func), \
73 | "0" (__val), "1" ((__val) >> 32), "c" (__msr) \
| ^~~~~
In file included from arch/x86/kernel/asm-offsets.c:10:
In file included from include/crypto/aria.h:22:
In file included from include/linux/module.h:20:
In file included from include/linux/elf.h:6:
In file included from arch/x86/include/asm/elf.h:10:
In file included from arch/x86/include/asm/ia32.h:7:
In file included from include/linux/compat.h:17:
In file included from include/linux/fs.h:5:
In file included from include/linux/fs/super.h:5:
In file included from include/linux/fs/super_types.h:13:
In file included from include/linux/percpu-rwsem.h:7:
In file included from include/linux/rcuwait.h:6:
In file included from include/linux/sched/signal.h:6:
include/linux/signal.h:98:11: warning: array index 3 is past the end of the array (that has type 'unsigned long[1]') [-Warray-bounds]
98 | return (set->sig[3] | set->sig[2] |
| ^ ~
arch/x86/include/asm/signal.h:24:2: note: array 'sig' declared here
24 | unsigned long sig[_NSIG_WORDS];
| ^
In file included from arch/x86/kernel/asm-offsets.c:10:
In file included from include/crypto/aria.h:22:
In file included from include/linux/module.h:20:
In file included from include/linux/elf.h:6:
In file included from arch/x86/include/asm/elf.h:10:
In file included from arch/x86/include/asm/ia32.h:7:
In file included from include/linux/compat.h:17:
In file included from include/linux/fs.h:5:
In file included from include/linux/fs/super.h:5:
In file included from include/linux/fs/super_types.h:13:
In file included from include/linux/percpu-rwsem.h:7:
In file included from include/linux/rcuwait.h:6:
In file included from include/linux/sched/signal.h:6:
include/linux/signal.h:98:25: warning: array index 2 is past the end of the array (that has type 'unsigned long[1]') [-Warray-bounds]
98 | return (set->sig[3] | set->sig[2] |
| ^ ~
arch/x86/include/asm/signal.h:24:2: note: array 'sig' declared here
24 | unsigned long sig[_NSIG_WORDS];
| ^
In file included from arch/x86/kernel/asm-offsets.c:10:
In file included from include/crypto/aria.h:22:
In file included from include/linux/module.h:20:
In file included from include/linux/elf.h:6:
In file included from arch/x86/include/asm/elf.h:10:
In file included from arch/x86/include/asm/ia32.h:7:
In file included from include/linux/compat.h:17:
In file included from include/linux/fs.h:5:
In file included from include/linux/fs/super.h:5:
In file included from include/linux/fs/super_types.h:13:
In file included from include/linux/percpu-rwsem.h:7:
In file included from include/linux/rcuwait.h:6:
In file included from include/linux/sched/signal.h:6:
include/linux/signal.h:99:4: warning: array index 1 is past the end of the array (that has type 'unsigned long[1]') [-Warray-bounds]
99 | set->sig[1] | set->sig[0]) == 0;
| ^ ~
arch/x86/include/asm/signal.h:24:2: note: array 'sig' declared here
24 | unsigned long sig[_NSIG_WORDS];
| ^
In file included from arch/x86/kernel/asm-offsets.c:10:
In file included from include/crypto/aria.h:22:
In file included from include/linux/module.h:20:
In file included from include/linux/elf.h:6:
In file included from arch/x86/include/asm/elf.h:10:
In file included from arch/x86/include/asm/ia32.h:7:
In file included from include/linux/compat.h:17:
In file included from include/linux/fs.h:5:

vim +114 arch/x86/include/asm/paravirt-msr.h

108
109 static __always_inline void write_msr(u32 msr, u64 val)
110 {
111 int err;
112
113 if (__builtin_constant_p(msr))
> 114 PV_WRMSR_CONST(msr, val, EX_TYPE_WRMSR, write_msr, err);
115 else
116 PV_WRMSR_VAR(msr, val, EX_TYPE_WRMSR, write_msr, err);
117 }
118

Will be fixed in V4.

Juergen

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