Re: [PATCH kvmtool] x86: Fixed Unable to execute init process since glibc version 2.33

[Alexandru Elisei <alexandru.elisei@arm.com>]

Hi,

On Sat, Feb 26, 2022 at 02:00:48PM +0800, Dongli Si wrote:
> From: Dongli Si <sidongli1997@gmail.com>
> 
> glibc detected invalid CPU Vendor name will cause an error:
> 
> [    0.450127] Run /sbin/init as init process
> /lib64/libc.so.6: CPU ISA level is lower than required
> [    0.451931] Kernel panic - not syncing: Attempted to kill init! exitcode=0x00007f00
> [    0.452117] CPU: 0 PID: 1 Comm: init Not tainted 5.17.0-rc1 #72

This looks bad. I'll try to reproduce it and I'll give my Tested-by tag after I
test it.

Thanks,
Alex

> 
> Signed-off-by: Dongli Si <sidongli1997@gmail.com>
> ---
>  x86/cpuid.c | 14 +++++++++-----
>  1 file changed, 9 insertions(+), 5 deletions(-)
> 
> diff --git a/x86/cpuid.c b/x86/cpuid.c
> index c3b67d9..d58a027 100644
> --- a/x86/cpuid.c
> +++ b/x86/cpuid.c
> @@ -2,6 +2,7 @@
>  
>  #include "kvm/kvm.h"
>  #include "kvm/util.h"
> +#include "kvm/cpufeature.h"
>  
>  #include <sys/ioctl.h>
>  #include <stdlib.h>
> @@ -10,7 +11,7 @@
>  
>  static void filter_cpuid(struct kvm_cpuid2 *kvm_cpuid)
>  {
> -	unsigned int signature[3];
> +	struct cpuid_regs regs;
>  	unsigned int i;
>  
>  	/*
> @@ -22,10 +23,13 @@ static void filter_cpuid(struct kvm_cpuid2 *kvm_cpuid)
>  		switch (entry->function) {
>  		case 0:
>  			/* Vendor name */
> -			memcpy(signature, "LKVMLKVMLKVM", 12);
> -			entry->ebx = signature[0];
> -			entry->ecx = signature[1];
> -			entry->edx = signature[2];
> +			regs = (struct cpuid_regs) {
> +				.eax		= 0x00,
> +			};
> +			host_cpuid(&regs);
> +			entry->ebx = regs.ebx;
> +			entry->ecx = regs.ecx;
> +			entry->edx = regs.edx;
>  			break;
>  		case 1:
>  			/* Set X86_FEATURE_HYPERVISOR */
> -- 
> 2.32.0
>