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From:   isaku.yamahata@gmail.com
Date:   Thu, 24 Mar 2022 11:18:32 -0700
To:     Kai Huang <kai.huang@intel.com>
Cc:     linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
        dave.hansen@intel.com, seanjc@google.com, pbonzini@redhat.com,
        kirill.shutemov@linux.intel.com,
        sathyanarayanan.kuppuswamy@linux.intel.com, peterz@infradead.org,
        tony.luck@intel.com, ak@linux.intel.com, dan.j.williams@intel.com,
        isaku.yamahata@intel.com, isaku.yamahata@gmail.com
Subject: Re: [PATCH v2 17/21] x86/virt/tdx: Configure global KeyID on all
 packages
Message-ID: <20220324181832.GC1212881@ls.amr.corp.intel.com>
References: <cover.1647167475.git.kai.huang@intel.com>
 <c36456b0fd4bd50720bc8e8aa35fbb124185ae98.1647167475.git.kai.huang@intel.com>
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0;136;0cFrom: Isaku Yamahata <isaku.yamahata@gmail.com>
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On Sun, Mar 13, 2022 at 11:49:57PM +1300,
Kai Huang <kai.huang@intel.com> wrote:

> diff --git a/arch/x86/virt/vmx/tdx.c b/arch/x86/virt/vmx/tdx.c
> index e03dc3e420db..39b1b7d0417d 100644
> --- a/arch/x86/virt/vmx/tdx.c
> +++ b/arch/x86/virt/vmx/tdx.c
> @@ -23,6 +23,7 @@
>  #include <asm/virtext.h>
>  #include <asm/e820/api.h>
>  #include <asm/pgtable.h>
> +#include <asm/smp.h>
>  #include <asm/tdx.h>
>  #include "tdx.h"
>  
> @@ -398,6 +399,47 @@ static int seamcall_on_each_cpu(struct seamcall_ctx *sc)
>  	return atomic_read(&sc->err);
>  }
>  
> +/*
> + * Call the SEAMCALL on one (any) cpu for each physical package in
> + * serialized way.  Note for serialized calls 'seamcall_ctx::err'
> + * doesn't have to be atomic, but for simplicity just reuse it
> + * instead of adding a new one.
> + *
> + * Return -ENXIO if IPI SEAMCALL wasn't run on any cpu, or -EFAULT
> + * when SEAMCALL fails, or -EPERM when the cpu where SEAMCALL runs
> + * on is not in VMX operation.  In case of -EFAULT, the error code
> + * of SEAMCALL is in 'struct seamcall_ctx::seamcall_ret'.
> + */
> +static int seamcall_on_each_package_serialized(struct seamcall_ctx *sc)
> +{
> +	cpumask_var_t packages;
> +	int cpu, ret;
> +
> +	if (!zalloc_cpumask_var(&packages, GFP_KERNEL))
> +		return -ENOMEM;

Memory leak. This should be freed before returning.


> +	for_each_online_cpu(cpu) {
> +		if (cpumask_test_and_set_cpu(topology_physical_package_id(cpu),
> +					packages))
> +			continue;
> +
> +		ret = smp_call_function_single(cpu, seamcall_smp_call_function,
> +				sc, true);
> +		if (ret)
> +			return ret;
> +
> +		/*
> +		 * Doesn't have to use atomic_read(), but it doesn't
> +		 * hurt either.
> +		 */
> +		ret = atomic_read(&sc->err);
> +		if (ret)
> +			return ret;
> +	}
> +
> +	return 0;
> +}
> +
>  static inline bool p_seamldr_ready(void)
>  {
>  	return !!p_seamldr_info.p_seamldr_ready;
> @@ -1316,6 +1358,18 @@ static int config_tdx_module(struct tdmr_info **tdmr_array, int tdmr_num,
>  	return ret;
>  }
>  
> +static int config_global_keyid(u64 global_keyid)

global_keyid argument isn't used.  Is global variable tdx_global_keyid used?


> +{
> +	struct seamcall_ctx sc = { .fn = TDH_SYS_KEY_CONFIG };
> +
> +	/*
> +	 * TDH.SYS.KEY.CONFIG may fail with entropy error (which is
> +	 * a recoverable error).  Assume this is exceedingly rare and
> +	 * just return error if encountered instead of retrying.
> +	 */
> +	return seamcall_on_each_package_serialized(&sc);
> +}
> +
-- 
Isaku Yamahata <isaku.yamahata@gmail.com>