linux-kernel - [PATCH v1 1/6] x86/tdx: Add TDREPORT TDX Module call support

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Message-Id: <96a89d74009b3a66a48eae26849c4bfe3dfdf6bc.1624719668.git.sathyanarayanan.kuppuswamy@linux.intel.com>
Date:   Sat, 26 Jun 2021 08:11:41 -0700
From:   Kuppuswamy Sathyanarayanan 
        <sathyanarayanan.kuppuswamy@...ux.intel.com>
To:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Peter Zijlstra <peterz@...radead.org>,
        Andy Lutomirski <luto@...nel.org>
Cc:     Peter H Anvin <hpa@...or.com>, Dave Hansen <dave.hansen@...el.com>,
        Tony Luck <tony.luck@...el.com>,
        Dan Williams <dan.j.williams@...el.com>,
        Andi Kleen <ak@...ux.intel.com>,
        Kirill Shutemov <kirill.shutemov@...ux.intel.com>,
        Sean Christopherson <seanjc@...gle.com>,
        Kuppuswamy Sathyanarayanan <knsathya@...nel.org>,
        x86@...nel.org, linux-kernel@...r.kernel.org
Subject: [PATCH v1 1/6] x86/tdx: Add TDREPORT TDX Module call support

The TDX Guest-Host Communication Interface (GHCI) includes a module
call (TDREPORT TDCALL) that a guest can make to acquire a copy of the
attestation data that it needs to verify its trustworthiness.

Add a wrapper function tdx_mcall_tdreport() that makes the module
call to get this data.

See GHCI section 2.4.5 "TDCALL [TDG.MR.REPORT] leaf" for additional
details.

[Xiaoyao: Proposed error code fix]
Reviewed-by: Tony Luck <tony.luck@...el.com>
Reviewed-by: Andi Kleen <ak@...ux.intel.com>
Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@...ux.intel.com>
---
 arch/x86/include/asm/tdx.h |  2 ++
 arch/x86/kernel/tdx.c      | 33 +++++++++++++++++++++++++++++++++
 2 files changed, 35 insertions(+)

diff --git a/arch/x86/include/asm/tdx.h b/arch/x86/include/asm/tdx.h
index 48927fac9e12..4f1b5c14a09b 100644
--- a/arch/x86/include/asm/tdx.h
+++ b/arch/x86/include/asm/tdx.h
@@ -96,6 +96,8 @@ extern int tdx_hcall_gpa_intent(phys_addr_t gpa, int numpages,
 
 bool tdg_filter_enabled(void);
 
+int tdx_mcall_tdreport(u64 data, u64 reportdata);
+
 /*
  * To support I/O port access in decompressor or early kernel init
  * code, since #VE exception handler cannot be used, use paravirt
diff --git a/arch/x86/kernel/tdx.c b/arch/x86/kernel/tdx.c
index f76af7661046..0f797803f4c8 100644
--- a/arch/x86/kernel/tdx.c
+++ b/arch/x86/kernel/tdx.c
@@ -23,6 +23,7 @@
 /* TDX Module call Leaf IDs */
 #define TDINFO				1
 #define TDGETVEINFO			3
+#define TDREPORT			4
 #define TDACCEPTPAGE			6
 
 /* TDX hypercall Leaf IDs */
@@ -30,6 +31,11 @@
 
 /* TDX Module call error codes */
 #define TDX_PAGE_ALREADY_ACCEPTED       0x8000000000000001
+#define TDCALL_RETURN_CODE_MASK		0xFFFFFFFF00000000
+#define TDCALL_OPERAND_BUSY		0x8000020000000000
+#define TDCALL_INVALID_OPERAND		0x8000000000000000
+#define TDCALL_RETURN_CODE(a)		((a) & TDCALL_RETURN_CODE_MASK)
+
 
 #define VE_IS_IO_OUT(exit_qual)		(((exit_qual) & 8) ? 0 : 1)
 #define VE_GET_IO_SIZE(exit_qual)	(((exit_qual) & 7) + 1)
@@ -139,6 +145,33 @@ static bool tdg_perfmon_enabled(void)
 	return td_info.attributes & BIT(63);
 }
 
+/*
+ * tdx_mcall_tdreport() - Generate TDREPORT_STRUCT using TDCALL.
+ *
+ * @data        : Physical address of 1024B aligned data to store
+ *                TDREPORT_STRUCT.
+ * @reportdata  : Physical address of 64B aligned report data
+ *
+ * return 0 on success or failure error number.
+ */
+int tdx_mcall_tdreport(u64 data, u64 reportdata)
+{
+	u64 ret;
+
+	if (!data || !reportdata || !prot_guest_has(PR_GUEST_TDX))
+		return -EINVAL;
+
+	ret = __trace_tdx_module_call(TDREPORT, data, reportdata, 0, 0, NULL);
+
+	if (TDCALL_RETURN_CODE(ret) == TDCALL_INVALID_OPERAND)
+		return -EINVAL;
+	else if (TDCALL_RETURN_CODE(ret) == TDCALL_OPERAND_BUSY)
+		return -EBUSY;
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(tdx_mcall_tdreport);
+
 static void tdg_get_info(void)
 {
 	u64 ret;
-- 
2.25.1