linux-kernel - Re: [PATCH v12 14/22] x86/virt/tdx: Configure TDX module with the TDMRs and global KeyID

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Date:   Wed, 5 Jul 2023 14:49:19 +0800
From:   Yuan Yao <yuan.yao@...ux.intel.com>
To:     Kai Huang <kai.huang@...el.com>
Cc:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
        linux-mm@...ck.org, x86@...nel.org, dave.hansen@...el.com,
        kirill.shutemov@...ux.intel.com, tony.luck@...el.com,
        peterz@...radead.org, tglx@...utronix.de, bp@...en8.de,
        mingo@...hat.com, hpa@...or.com, seanjc@...gle.com,
        pbonzini@...hat.com, david@...hat.com, dan.j.williams@...el.com,
        rafael.j.wysocki@...el.com, ashok.raj@...el.com,
        reinette.chatre@...el.com, len.brown@...el.com, ak@...ux.intel.com,
        isaku.yamahata@...el.com, ying.huang@...el.com, chao.gao@...el.com,
        sathyanarayanan.kuppuswamy@...ux.intel.com, nik.borisov@...e.com,
        bagasdotme@...il.com, sagis@...gle.com, imammedo@...hat.com
Subject: Re: [PATCH v12 14/22] x86/virt/tdx: Configure TDX module with the
 TDMRs and global KeyID

On Tue, Jun 27, 2023 at 02:12:44AM +1200, Kai Huang wrote:
> The TDX module uses a private KeyID as the "global KeyID" for mapping
> things like the PAMT and other TDX metadata.  This KeyID has already
> been reserved when detecting TDX during the kernel early boot.
>
> After the list of "TD Memory Regions" (TDMRs) has been constructed to
> cover all TDX-usable memory regions, the next step is to pass them to
> the TDX module together with the global KeyID.

Reviewed-by: Yuan Yao <yuan.yao@...el.com>

>
> Signed-off-by: Kai Huang <kai.huang@...el.com>
> Reviewed-by: Isaku Yamahata <isaku.yamahata@...el.com>
> Reviewed-by: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>
> ---
>
> v11 -> v12:
>  - Added Kirill's tag
>
> v10 -> v11:
>  - No update
>
> v9 -> v10:
>  - Code change due to change static 'tdx_tdmr_list' to local 'tdmr_list'.
>
> v8 -> v9:
>  - Improved changlog to explain why initializing TDMRs can take long
>    time (Dave).
>  - Improved comments around 'next-to-initialize' address (Dave).
>
> v7 -> v8: (Dave)
>  - Changelog:
>    - explicitly call out this is the last step of TDX module initialization.
>    - Trimed down changelog by removing SEAMCALL name and details.
>  - Removed/trimmed down unnecessary comments.
>  - Other changes due to 'struct tdmr_info_list'.
>
> v6 -> v7:
>  - Removed need_resched() check. -- Andi.
>
>
> ---
>  arch/x86/virt/vmx/tdx/tdx.c | 41 ++++++++++++++++++++++++++++++++++++-
>  arch/x86/virt/vmx/tdx/tdx.h |  2 ++
>  2 files changed, 42 insertions(+), 1 deletion(-)
>
> diff --git a/arch/x86/virt/vmx/tdx/tdx.c b/arch/x86/virt/vmx/tdx/tdx.c
> index 2bcace5cb25c..1992245290de 100644
> --- a/arch/x86/virt/vmx/tdx/tdx.c
> +++ b/arch/x86/virt/vmx/tdx/tdx.c
> @@ -26,6 +26,7 @@
>  #include <linux/pfn.h>
>  #include <linux/align.h>
>  #include <linux/sort.h>
> +#include <linux/log2.h>
>  #include <asm/msr-index.h>
>  #include <asm/msr.h>
>  #include <asm/archrandom.h>
> @@ -864,6 +865,39 @@ static int construct_tdmrs(struct list_head *tmb_list,
>  	return ret;
>  }
>
> +static int config_tdx_module(struct tdmr_info_list *tdmr_list, u64 global_keyid)
> +{
> +	u64 *tdmr_pa_array;
> +	size_t array_sz;
> +	int i, ret;
> +
> +	/*
> +	 * TDMRs are passed to the TDX module via an array of physical
> +	 * addresses of each TDMR.  The array itself also has certain
> +	 * alignment requirement.
> +	 */
> +	array_sz = tdmr_list->nr_consumed_tdmrs * sizeof(u64);
> +	array_sz = roundup_pow_of_two(array_sz);
> +	if (array_sz < TDMR_INFO_PA_ARRAY_ALIGNMENT)
> +		array_sz = TDMR_INFO_PA_ARRAY_ALIGNMENT;
> +
> +	tdmr_pa_array = kzalloc(array_sz, GFP_KERNEL);
> +	if (!tdmr_pa_array)
> +		return -ENOMEM;
> +
> +	for (i = 0; i < tdmr_list->nr_consumed_tdmrs; i++)
> +		tdmr_pa_array[i] = __pa(tdmr_entry(tdmr_list, i));
> +
> +	ret = seamcall(TDH_SYS_CONFIG, __pa(tdmr_pa_array),
> +				tdmr_list->nr_consumed_tdmrs,
> +				global_keyid, 0, NULL, NULL);
> +
> +	/* Free the array as it is not required anymore. */
> +	kfree(tdmr_pa_array);
> +
> +	return ret;
> +}
> +
>  static int init_tdx_module(void)
>  {
>  	struct tdsysinfo_struct *sysinfo;
> @@ -917,16 +951,21 @@ static int init_tdx_module(void)
>  	if (ret)
>  		goto out_free_tdmrs;
>
> +	/* Pass the TDMRs and the global KeyID to the TDX module */
> +	ret = config_tdx_module(&tdmr_list, tdx_global_keyid);
> +	if (ret)
> +		goto out_free_pamts;
> +
>  	/*
>  	 * TODO:
>  	 *
> -	 *  - Configure the TDMRs and the global KeyID to the TDX module.
>  	 *  - Configure the global KeyID on all packages.
>  	 *  - Initialize all TDMRs.
>  	 *
>  	 *  Return error before all steps are done.
>  	 */
>  	ret = -EINVAL;
> +out_free_pamts:
>  	if (ret)
>  		tdmrs_free_pamt_all(&tdmr_list);
>  	else
> diff --git a/arch/x86/virt/vmx/tdx/tdx.h b/arch/x86/virt/vmx/tdx/tdx.h
> index 9b5a65f37e8b..c386aa3afe2a 100644
> --- a/arch/x86/virt/vmx/tdx/tdx.h
> +++ b/arch/x86/virt/vmx/tdx/tdx.h
> @@ -24,6 +24,7 @@
>  #define TDH_SYS_INFO		32
>  #define TDH_SYS_INIT		33
>  #define TDH_SYS_LP_INIT		35
> +#define TDH_SYS_CONFIG		45
>
>  struct cmr_info {
>  	u64	base;
> @@ -88,6 +89,7 @@ struct tdmr_reserved_area {
>  } __packed;
>
>  #define TDMR_INFO_ALIGNMENT	512
> +#define TDMR_INFO_PA_ARRAY_ALIGNMENT	512
>
>  struct tdmr_info {
>  	u64 base;
> --
> 2.40.1
>