linux-kernel - Re: [PATCH 08/13] x86/virt/tdx: Add SEAMCALL wrappers to add TD private pages

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Message-ID: <c11d9dce9eb334e34ba46e2f17ec3993e3935a31.camel@intel.com>
Date: Thu, 2 Jan 2025 23:32:46 +0000
From: "Edgecombe, Rick P" <rick.p.edgecombe@...el.com>
To: "kvm@...r.kernel.org" <kvm@...r.kernel.org>, "pbonzini@...hat.com"
	<pbonzini@...hat.com>, "linux-kernel@...r.kernel.org"
	<linux-kernel@...r.kernel.org>
CC: "Zhao, Yan Y" <yan.y.zhao@...el.com>, "Huang, Kai" <kai.huang@...el.com>,
	"dave.hansen@...ux.intel.com" <dave.hansen@...ux.intel.com>, "Yamahata,
 Isaku" <isaku.yamahata@...el.com>
Subject: Re: [PATCH 08/13] x86/virt/tdx: Add SEAMCALL wrappers to add TD
 private pages

On Wed, 2025-01-01 at 02:49 -0500, Paolo Bonzini wrote:
> diff --git a/arch/x86/virt/vmx/tdx/tdx.c b/arch/x86/virt/vmx/tdx/tdx.c
> index a97a470dda23..f39197d4eafc 100644
> --- a/arch/x86/virt/vmx/tdx/tdx.c
> +++ b/arch/x86/virt/vmx/tdx/tdx.c
> @@ -1491,6 +1491,26 @@ u64 tdh_mng_addcx(struct tdx_td *td, struct page *tdcs_page)
>  }
>  EXPORT_SYMBOL_GPL(tdh_mng_addcx);
>  
> +u64 tdh_mem_page_add(struct tdx_td *td, u64 gpa, u64 hpa, u64 source, u64 *rcx, u64 *rdx)
> +{

u64 gpa could be gfn_t.

hpa and source should be struct pages, per:
https://lore.kernel.org/kvm/d92e5301-9ca4-469a-8ae5-b36426e67356@intel.com/

> +	struct tdx_module_args args = {
> +		.rcx = gpa,

This could potentially also use union tdx_sept_gpa_mapping_info.

> +		.rdx = tdx_tdr_pa(td),
> +		.r8 = hpa,
> +		.r9 = source,
> +	};
> +	u64 ret;
> +
> +	clflush_cache_range(__va(hpa), PAGE_SIZE);
> +	ret = seamcall_ret(TDH_MEM_PAGE_ADD, &args);
> +
> +	*rcx = args.rcx;
> +	*rdx = args.rdx;

Similar to the last patch, these could be extended_err1, extended_err2.

> +
> +	return ret;
> +}
> +EXPORT_SYMBOL_GPL(tdh_mem_page_add);
> +
>  u64 tdh_mem_sept_add(struct tdx_td *td, u64 gpa, u64 level, u64 hpa, u64 *rcx, u64 *rdx)
>  {
>  	struct tdx_module_args args = {
> @@ -1522,6 +1542,25 @@ u64 tdh_vp_addcx(struct tdx_vp *vp, struct page *tdcx_page)
>  }
>  EXPORT_SYMBOL_GPL(tdh_vp_addcx);
>  
> +u64 tdh_mem_page_aug(struct tdx_td *td, u64 gpa, u64 hpa, u64 *rcx, u64 *rdx)
> +{

hpa should be struct page, or as Yan had been ready to propose a folio and idx.
I would have thought a struct page would be sufficient for now. She also planned
to add a level arg, which today should always be 4k, but would be needed for
future huge page support.

I think we should try to keep it as simple as possible for now.

> +	struct tdx_module_args args = {
> +		.rcx = gpa,
> +		.rdx = tdx_tdr_pa(td),
> +		.r8 = hpa,
> +	};
> +	u64 ret;
> +
> +	clflush_cache_range(__va(hpa), PAGE_SIZE);
> +	ret = seamcall_ret(TDH_MEM_PAGE_AUG, &args);
> +
> +	*rcx = args.rcx;
> +	*rdx = args.rdx;

Similar to the others, these could be extended_err1, extended_err2.

> +
> +	return ret;
> +}
> +EXPORT_SYMBOL_GPL(tdh_mem_page_aug);
> +
>  u64 tdh_mng_key_config(struct tdx_td *td)
>  {
>  	struct tdx_module_args args = {
> diff --git a/arch/x86/virt/vmx/tdx/tdx.h b/arch/x86/virt/vmx/tdx/tdx.h
> index 308d3aa565d7..80e6ef006085 100644
> --- a/arch/x86/virt/vmx/tdx/tdx.h
> +++ b/arch/x86/virt/vmx/tdx/tdx.h
> @@ -16,8 +16,10 @@
>   * TDX module SEAMCALL leaf functions
>   */
>  #define TDH_MNG_ADDCX			1
> +#define TDH_MEM_PAGE_ADD		2
>  #define TDH_MEM_SEPT_ADD		3
>  #define TDH_VP_ADDCX			4
> +#define TDH_MEM_PAGE_AUG		6
>  #define TDH_MNG_KEY_CONFIG		8
>  #define TDH_MNG_CREATE			9
>  #define TDH_MNG_RD			11