Re: [Xen-devel] [PATCH] x86/amd: fix crash as Xen Dom0 on AMD Trinity systems

[Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>]

On Wed, May 30, 2012 at 03:10:02PM +0200, Andre Przywara wrote:
> Because we are behind a family check before tweaking the topology
> bit, we can use the standard rd/wrmsr variants for the CPUID feature
> register.
> This fixes a crash when using the kernel as a Xen Dom0 on affected
> Trinity systems. The wrmsrl_amd_safe is not properly paravirtualized
> yet (this will be fixed in another patch).

So with a rdmsrl_amd_safe and wrmsrl_amd_safe being implemented in
the pv_cpu_ops - would this patch even be neccessary?

> 
> Signed-off-by: Andre Przywara <andre.przywara@amd.com>
> Cc: stable@vger.kernel.org # 3.4+
> ---
>  arch/x86/kernel/cpu/amd.c |    4 ++--
>  1 files changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c
> index 146bb62..80ccd99 100644
> --- a/arch/x86/kernel/cpu/amd.c
> +++ b/arch/x86/kernel/cpu/amd.c
> @@ -586,9 +586,9 @@ static void __cpuinit init_amd(struct cpuinfo_x86 *c)
>  	    !cpu_has(c, X86_FEATURE_TOPOEXT)) {
>  		u64 val;
>  
> -		if (!rdmsrl_amd_safe(0xc0011005, &val)) {
> +		if (!rdmsrl_safe(0xc0011005, &val)) {
>  			val |= 1ULL << 54;
> -			wrmsrl_amd_safe(0xc0011005, val);
> +			checking_wrmsrl(0xc0011005, val);
>  			rdmsrl(0xc0011005, val);
>  			if (val & (1ULL << 54)) {
>  				set_cpu_cap(c, X86_FEATURE_TOPOEXT);
> -- 
> 1.7.4.4
> 
> 
> 
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