linux-kernel - Re: [PATCH 07/13] x86/virt/tdx: Add SEAMCALL wrapper tdh_mem_sept

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Message-ID: <Z3y7RQCT5/chcdHs@yzhao56-desk.sh.intel.com>
Date: Tue, 7 Jan 2025 13:27:33 +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>, "sean.j.christopherson@...el.com"
	<sean.j.christopherson@...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 07/13] x86/virt/tdx: Add SEAMCALL wrapper
 tdh_mem_sept_add() to add SEPT pages

Here's the proposed new version with changelog:
SEAMCALL RFC:
    - Use struct tdx_td instead of raw TDR u64.
    - Use "struct page *" for sept_page instead of raw hpa.
    - Change "u64 level" to "int level".
    - Rename "level" to "tdx_level" as it's tdx specfic. (Rick)
    - Change "u64 gpa" to "gfn_t gfn". (Reinette)
    - Introduce a union tdx_sept_gpa_mapping_info to initialize args.rcx.
      (Reinette)
    - Call tdx_clflush_page() instead of clflush_cache_range().
    - Use extended_err1/2 instead of rcx/rdx for output.


diff --git a/arch/x86/include/asm/shared/tdx.h b/arch/x86/include/asm/shared/tdx.h
index c6d0668de167..ea5a98fd1dd5 100644
--- a/arch/x86/include/asm/shared/tdx.h
+++ b/arch/x86/include/asm/shared/tdx.h
@@ -105,6 +105,20 @@ struct tdx_module_args {
        u64 rsi;
 };
 
+/*
+ * Used to specify SEPT GPA mapping information for SEPT related SEAMCALLs and
+ * TDCALLs.
+ */
+union tdx_sept_gpa_mapping_info {
+       struct {
+               u64 level       : 3;
+               u64 reserved1   : 9;
+               u64 gfn         : 40;
+               u64 reserved2   : 12;
+       };
+       u64 full;
+};
+
 /* Used to communicate with the TDX module */
 u64 __tdcall(u64 fn, struct tdx_module_args *args);
 u64 __tdcall_ret(u64 fn, struct tdx_module_args *args);
diff --git a/arch/x86/include/asm/tdx.h b/arch/x86/include/asm/tdx.h
index bbb8f0bae9ba..787c359a5fc9 100644
--- a/arch/x86/include/asm/tdx.h
+++ b/arch/x86/include/asm/tdx.h
@@ -33,6 +33,7 @@
 #ifndef __ASSEMBLY__
 
 #include <uapi/asm/mce.h>
+#include <linux/kvm_types.h>
 #include "tdx_global_metadata.h"
 
 /*
@@ -143,6 +144,8 @@ struct tdx_vp {
 };
 
 u64 tdh_mng_addcx(struct tdx_td *td, struct page *tdcs_page);
+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);
 u64 tdh_mng_key_config(struct tdx_td *td);
 u64 tdh_mng_create(struct tdx_td *td, u64 hkid);
diff --git a/arch/x86/virt/vmx/tdx/tdx.c b/arch/x86/virt/vmx/tdx/tdx.c
index a16c507296df..adb2059b6b5f 100644
--- a/arch/x86/virt/vmx/tdx/tdx.c
+++ b/arch/x86/virt/vmx/tdx/tdx.c
@@ -1583,6 +1583,27 @@ u64 tdh_mng_addcx(struct tdx_td *td, struct page *tdcs_page)
 }
 EXPORT_SYMBOL_GPL(tdh_mng_addcx);
 
+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)
+{
+       union tdx_sept_gpa_mapping_info gpa_info = { .level = tdx_level, .gfn = gfn, };
+       struct tdx_module_args args = {
+               .rcx = gpa_info.full,
+               .rdx = tdx_tdr_pa(td),
+               .r8 = page_to_phys(sept_page),
+       };
+       u64 ret;
+
+       tdx_clflush_page(sept_page);
+       ret = seamcall_ret(TDH_MEM_SEPT_ADD, &args);
+
+       *extended_err1 = args.rcx;
+       *extended_err2 = args.rdx;
+
+       return ret;
+}
+EXPORT_SYMBOL_GPL(tdh_mem_sept_add);
+
 u64 tdh_vp_addcx(struct tdx_vp *vp, struct page *tdcx_page)
 {
        struct tdx_module_args args = {
diff --git a/arch/x86/virt/vmx/tdx/tdx.h b/arch/x86/virt/vmx/tdx/tdx.h
index 08b01b7fe7c2..0d1ba0d0ac82 100644
--- a/arch/x86/virt/vmx/tdx/tdx.h
+++ b/arch/x86/virt/vmx/tdx/tdx.h
@@ -18,6 +18,7 @@
  * TDX module SEAMCALL leaf functions
  */
 #define TDH_MNG_ADDCX                  1
+#define TDH_MEM_SEPT_ADD               3
 #define TDH_VP_ADDCX                   4
 #define TDH_MNG_KEY_CONFIG             8
 #define TDH_MNG_CREATE                 9