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From:   Smita Koralahalli <Smita.KoralahalliChannabasappa@amd.com>
To:     x86@kernel.org, linux-edac@vger.kernel.org,
        linux-kernel@vger.kernel.org
Cc:     Tony Luck <tony.luck@intel.com>, "H . Peter Anvin" <hpa@zytor.com>,
        yazen.ghannam@amd.com, Smita.KoralahalliChannabasappa@amd.com
Subject: [PATCH 1/5] x86/mce/inject: Check if a bank is unpopulated before error simulation
Date:   Wed, 15 Sep 2021 18:27:35 -0500
Message-Id: <20210915232739.6367-2-Smita.KoralahalliChannabasappa@amd.com>
In-Reply-To: <20210915232739.6367-1-Smita.KoralahalliChannabasappa@amd.com>
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The MCA_IPID register uniquely identifies a bank's type on Scalable MCA
(SMCA) systems. When an MCA bank is not populated, the MCA_IPID register
will read as zero and writes to it will be ignored. Check the value of
this register before trying to simulate the error.

Signed-off-by: Smita Koralahalli <Smita.KoralahalliChannabasappa@amd.com>
---
 arch/x86/kernel/cpu/mce/inject.c | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/arch/x86/kernel/cpu/mce/inject.c b/arch/x86/kernel/cpu/mce/inject.c
index 0bfc14041bbb..51ac575c4605 100644
--- a/arch/x86/kernel/cpu/mce/inject.c
+++ b/arch/x86/kernel/cpu/mce/inject.c
@@ -577,6 +577,24 @@ static int inj_bank_set(void *data, u64 val)
 	}
 
 	m->bank = val;
+
+	/* Read IPID value to determine if a bank is unpopulated on the target
+	 * CPU.
+	 */
+	if (boot_cpu_has(X86_FEATURE_SMCA)) {
+
+		/* Check for user provided IPID value. */
+		if (!m->ipid) {
+			rdmsrl_on_cpu(m->extcpu, MSR_AMD64_SMCA_MCx_IPID(val),
+				      &m->ipid);
+			if (!m->ipid) {
+				pr_err("Error simulation not possible: Bank %llu unpopulated\n",
+					val);
+				return -ENODEV;
+			}
+		}
+	}
+
 	do_inject();
 
 	/* Reset injection struct */
-- 
2.17.1