Received-SPF: Pass (protection.outlook.com: domain of amd.com designates
 165.204.84.17 as permitted sender) receiver=protection.outlook.com;
 client-ip=165.204.84.17; helo=SATLEXMB04.amd.com; pr=C
From:   Michael Roth <michael.roth@amd.com>
To:     <kvm@vger.kernel.org>
CC:     <linux-coco@lists.linux.dev>, <linux-mm@kvack.org>,
        <linux-crypto@vger.kernel.org>, <x86@kernel.org>,
        <linux-kernel@vger.kernel.org>, <tglx@linutronix.de>,
        <mingo@redhat.com>, <jroedel@suse.de>, <thomas.lendacky@amd.com>,
        <hpa@zytor.com>, <ardb@kernel.org>, <pbonzini@redhat.com>,
        <seanjc@google.com>, <vkuznets@redhat.com>, <jmattson@google.com>,
        <luto@kernel.org>, <dave.hansen@linux.intel.com>, <slp@redhat.com>,
        <pgonda@google.com>, <peterz@infradead.org>,
        <srinivas.pandruvada@linux.intel.com>, <rientjes@google.com>,
        <dovmurik@linux.ibm.com>, <tobin@ibm.com>, <bp@alien8.de>,
        <vbabka@suse.cz>, <kirill@shutemov.name>, <ak@linux.intel.com>,
        <tony.luck@intel.com>, <marcorr@google.com>,
        <sathyanarayanan.kuppuswamy@linux.intel.com>,
        <alpergun@google.com>, <dgilbert@redhat.com>, <jarkko@kernel.org>,
        <ashish.kalra@amd.com>, <nikunj.dadhania@amd.com>,
        Brijesh Singh <brijesh.singh@amd.com>
Subject: [PATCH RFC v8 13/56] x86/fault: Add helper for dumping RMP entries
Date:   Mon, 20 Feb 2023 12:38:04 -0600
Message-ID: <20230220183847.59159-14-michael.roth@amd.com>
In-Reply-To: <20230220183847.59159-1-michael.roth@amd.com>
References: <20230220183847.59159-1-michael.roth@amd.com>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Content-Type: text/plain
X-MS-Exchange-CrossTenant-OriginalArrivalTime: 20 Feb 2023 18:44:56.9088
 (UTC)
X-MS-Exchange-CrossTenant-Network-Message-Id: 26894fc4-1c33-4779-bf79-08db1372903a
X-MS-Exchange-CrossTenant-Id: 3dd8961f-e488-4e60-8e11-a82d994e183d
X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=3dd8961f-e488-4e60-8e11-a82d994e183d;Ip=[165.204.84.17];Helo=[SATLEXMB04.amd.com]
X-MS-Exchange-CrossTenant-AuthSource: DM6NAM11FT090.eop-nam11.prod.protection.outlook.com
X-MS-Exchange-CrossTenant-AuthAs: Anonymous
X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem
X-MS-Exchange-Transport-CrossTenantHeadersStamped: CY8PR12MB7754
Precedence: bulk
List-ID: <linux-crypto.vger.kernel.org>
X-Mailing-List: linux-crypto@vger.kernel.org

This information will be useful for debugging things like page faults
due to RMP access violations and RMPUPDATE failures.

Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
Signed-off-by: Ashish Kalra <ashish.kalra@amd.com>
[mdr: move helper to standalone patch]
Signed-off-by: Michael Roth <michael.roth@amd.com>
---
 arch/x86/include/asm/sev.h |  2 ++
 arch/x86/kernel/sev.c      | 48 ++++++++++++++++++++++++++++++++++++++
 2 files changed, 50 insertions(+)

diff --git a/arch/x86/include/asm/sev.h b/arch/x86/include/asm/sev.h
index 8d3ce2ad27da..edbb7fa488af 100644
--- a/arch/x86/include/asm/sev.h
+++ b/arch/x86/include/asm/sev.h
@@ -198,6 +198,7 @@ bool snp_init(struct boot_params *bp);
 void __init __noreturn snp_abort(void);
 int snp_issue_guest_request(u64 exit_code, struct snp_req_data *input, unsigned long *fw_err);
 int snp_lookup_rmpentry(u64 pfn, int *level);
+void sev_dump_rmpentry(u64 pfn);
 #else
 static inline void sev_es_ist_enter(struct pt_regs *regs) { }
 static inline void sev_es_ist_exit(void) { }
@@ -223,6 +224,7 @@ static inline int snp_issue_guest_request(u64 exit_code, struct snp_req_data *in
 	return -ENOTTY;
 }
 static inline int snp_lookup_rmpentry(u64 pfn, int *level) { return 0; }
+static inline void sev_dump_rmpentry(u64 pfn) {}
 #endif
 
 #endif
diff --git a/arch/x86/kernel/sev.c b/arch/x86/kernel/sev.c
index a063c1b98034..a01741c4a1b8 100644
--- a/arch/x86/kernel/sev.c
+++ b/arch/x86/kernel/sev.c
@@ -2504,6 +2504,54 @@ static struct rmpentry *__snp_lookup_rmpentry(u64 pfn, int *level)
 	return entry;
 }
 
+void sev_dump_rmpentry(u64 pfn)
+{
+	unsigned long pfn_end;
+	struct rmpentry *e;
+	int level;
+
+	e = __snp_lookup_rmpentry(pfn, &level);
+	if (IS_ERR(e)) {
+		pr_info("Failed to read RMP entry for PFN 0x%llx\n", pfn);
+		return;
+	}
+
+	if (rmpentry_assigned(e)) {
+		pr_info("RMPEntry paddr 0x%llx [assigned=%d immutable=%d pagesize=%d gpa=0x%lx asid=%d vmsa=%d validated=%d]\n",
+			pfn << PAGE_SHIFT, rmpentry_assigned(e), e->info.immutable,
+			rmpentry_pagesize(e), (unsigned long)e->info.gpa, e->info.asid,
+			e->info.vmsa, e->info.validated);
+
+		/* Dump all the non-zero entries if debug enabled */
+		if (!sev_cfg.debug)
+			return;
+	}
+
+	/*
+	 * If the RMP entry at the faulting pfn was not assigned, then not sure
+	 * what caused the RMP violation. To get some useful debug information,
+	 * iterate through the entire 2MB region, and dump the RMP entries if
+	 * one of the bit in the RMP entry is set.
+	 */
+	pfn = pfn & ~(PTRS_PER_PMD - 1);
+	pfn_end = pfn + PTRS_PER_PMD;
+
+	while (pfn < pfn_end) {
+		e = __snp_lookup_rmpentry(pfn, &level);
+		if (IS_ERR(e)) {
+			pr_info("Failed to read RMP entry for PFN 0x%llx\n", pfn);
+			pfn++;
+			continue;
+		}
+
+		if (e->low || e->high)
+			pr_info("RMPEntry paddr 0x%llx: [high=0x%016llx low=0x%016llx]\n",
+				pfn << PAGE_SHIFT, e->high, e->low);
+		pfn++;
+	}
+}
+EXPORT_SYMBOL_GPL(sev_dump_rmpentry);
+
 /*
  * Return 1 if the RMP entry is assigned, 0 if it exists but is not assigned,
  * and -errno if there is no corresponding RMP entry.
-- 
2.25.1