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

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Message-ID: <Z3zLq3BT3vIsB73o@yzhao56-desk.sh.intel.com>
Date: Tue, 7 Jan 2025 14:37:31 +0800
From: Yan Zhao <yan.y.zhao@...el.com>
To: "Edgecombe, Rick P" <rick.p.edgecombe@...el.com>
CC: "kvm@...r.kernel.org" <kvm@...r.kernel.org>, "pbonzini@...hat.com"
	<pbonzini@...hat.com>, "linux-kernel@...r.kernel.org"
	<linux-kernel@...r.kernel.org>, "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 Tue, Jan 07, 2025 at 03:21:40AM +0800, Edgecombe, Rick P wrote:
> On Mon, 2025-01-06 at 13:50 +0800, Yan Zhao wrote:
> > > I think we should try to keep it as simple as possible for now.
> > Yeah.
> > So, do you think we need to have tdh_mem_page_aug() to support 4K level page
> > only and ask for Dave's review again for huge page?
> > 
> > Do we need to add param "level" ?
> > - if yes, "struct page" looks not fit.
> > - if not, hardcode it as 0 in the wrapper and convert "pfn" to "struct page"?
> 
> My thoughts would be we should export just what is needed for today to keep
> things simple and speedy (skip level arg, support order 0 only), especially if
> we can drop all folio checks. The SEAMCALL wrappers will not be set in stone and
> it will be easier to review huge page required stuff in the context of already
> settled 4k support.
Ok. Attached the new diff for tdh_mem_page_aug() to support 4K only.
Have compiled and tested in my local env.
(I kept the tdx_level in tdh_mem_range_block() and tdh_mem_page_remove() in
later patches).

diff --git a/arch/x86/include/asm/tdx.h b/arch/x86/include/asm/tdx.h
index 787c359a5fc9..1db93e4886df 100644
--- a/arch/x86/include/asm/tdx.h
+++ b/arch/x86/include/asm/tdx.h
@@ -144,9 +144,14 @@ struct tdx_vp {
 };

 u64 tdh_mng_addcx(struct tdx_td *td, struct page *tdcs_page);
+u64 tdh_mem_page_add(struct tdx_td *td, gfn_t gfn, struct page *private_page,
+                    struct page *source_page, u64 *extended_err1, u64 *extended_err2);
 u64 tdh_mem_sept_add(struct tdx_td *td, gfn_t gfn, int tdx_level, struct page *sept_page,
                     u64 *extended_err1, u64 *extended_err2);
 u64 tdh_vp_addcx(struct tdx_vp *vp, struct page *tdcx_page);
+struct folio;
+u64 tdh_mem_page_aug(struct tdx_td *td, gfn_t gfn, struct page *private_page,
+                    u64 *extended_err1, u64 *extended_err2);
 u64 tdh_mng_key_config(struct tdx_td *td);
 u64 tdh_mng_create(struct tdx_td *td, u64 hkid);
 u64 tdh_vp_create(struct tdx_td *td, struct tdx_vp *vp);
diff --git a/arch/x86/virt/vmx/tdx/tdx.c b/arch/x86/virt/vmx/tdx/tdx.c
index adb2059b6b5f..cfedff43e1e0 100644
--- a/arch/x86/virt/vmx/tdx/tdx.c
+++ b/arch/x86/virt/vmx/tdx/tdx.c
@@ -1583,6 +1583,28 @@ 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, gfn_t gfn, struct page *private_page,
+                    struct page *source_page, u64 *extended_err1, u64 *extended_err2)
+{
+       union tdx_sept_gpa_mapping_info gpa_info = { .level = 0, .gfn = gfn, };
+       struct tdx_module_args args = {
+               .rcx = gpa_info.full,
+               .rdx = tdx_tdr_pa(td),
+               .r8 = page_to_phys(private_page),
+               .r9 = page_to_phys(source_page),
+       };
+       u64 ret;
+
+       tdx_clflush_page(private_page);
+       ret = seamcall_ret(TDH_MEM_PAGE_ADD, &args);
+
+       *extended_err1 = args.rcx;
+       *extended_err2 = args.rdx;
+
+       return ret;
+}
+EXPORT_SYMBOL_GPL(tdh_mem_page_add);
+
 u64 tdh_mem_sept_add(struct tdx_td *td, gfn_t gfn, int tdx_level, struct page *sept_page,
                     u64 *extended_err1, u64 *extended_err2)
 {
@@ -1616,6 +1638,28 @@ 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, gfn_t gfn, struct page *private_page,
+                    u64 *extended_err1, u64 *extended_err2)
+{
+       union tdx_sept_gpa_mapping_info gpa_info = { .level = 0, .gfn = gfn, };
+       struct tdx_module_args args = {
+               .rcx = gpa_info.full,
+               .rdx = tdx_tdr_pa(td),
+               .r8 = page_to_phys(private_page),
+       };
+       u64 ret;
+
+       tdx_clflush_page(private_page);
+
+       ret = seamcall_ret(TDH_MEM_PAGE_AUG, &args);
+
+       *extended_err1 = args.rcx;
+       *extended_err2 = args.rdx;
+
+       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 0d1ba0d0ac82..8a56e790f64d 100644
--- a/arch/x86/virt/vmx/tdx/tdx.h
+++ b/arch/x86/virt/vmx/tdx/tdx.h
@@ -18,8 +18,10 @@
  * 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