Re: [PATCH v8 2/7] x86/sev: Initialize RMPOPT configuration MSRs

[K Prateek Nayak]

Hello Ashish,

On 6/16/2026 1:18 AM, Ashish Kalra wrote:
> diff --git a/arch/x86/virt/svm/sev.c b/arch/x86/virt/svm/sev.c
> index 8bcdce98f6dc..1b5c18408f0b 100644
> --- a/arch/x86/virt/svm/sev.c
> +++ b/arch/x86/virt/svm/sev.c
> @@ -124,6 +124,10 @@ static void *rmp_bookkeeping __ro_after_init;
>  
>  static u64 probed_rmp_base, probed_rmp_size;
>  
> +static cpumask_t rmpopt_cpumask;

nit.

I believe you can use cpumask_var_t here and do a zalloc_cpumask_var()
during snp_setup_rmpopt(). That way !X86_FEATURE_RMPOPT configs don't
have to needlessly waste space to keep a redundant cpumask around.

Same comment for rmpopt_report_cpumask in Patch 7 which can be
allocated dynamically during rmpopt_debugfs_setup().

> +static phys_addr_t rmpopt_pa_start;
> +static bool rmpopt_configured;
> +
>  static LIST_HEAD(snp_leaked_pages_list);
>  static DEFINE_SPINLOCK(snp_leaked_pages_list_lock);
>  
> @@ -490,7 +494,12 @@ static bool __init setup_rmptable(void)
>  	if (rmp_cfg & MSR_AMD64_SEG_RMP_ENABLED) {
>  		if (!setup_segmented_rmptable())
>  			return false;
> +		rmpopt_configured = true;
>  	} else {
> +		/*
> +		 * RMPOPT requires a segmented RMP table, so leave
> +		 * rmpopt_configured clear on contiguous RMP systems.
> +		 */
>  		if (!setup_contiguous_rmptable())
>  			return false;
>  	}
> @@ -555,6 +564,21 @@ int snp_prepare(void)
>  }
>  EXPORT_SYMBOL_FOR_MODULES(snp_prepare, "ccp");
>  
> +static void rmpopt_cleanup(void)
> +{
> +	int cpu;
> +
> +	cpus_read_lock();

nit.

You can use guard(cpus_read_lock)() unless there is a complicated
locking pattern where you need to drop and re-acquire the read lock.

> +
> +	for_each_cpu(cpu, &rmpopt_cpumask)
> +		WARN_ON_ONCE(wrmsrq_on_cpu(cpu, MSR_AMD64_RMPOPT_BASE, 0));
> +
> +	cpus_read_unlock();
> +
> +	cpumask_clear(&rmpopt_cpumask);
> +	rmpopt_pa_start = 0;
> +}
> +
>  void snp_shutdown(void)
>  {
>  	u64 syscfg;

-- 
Thanks and Regards,
Prateek