linux-kernel - [PATCH] SYSFS reporting of L1TF on PowerPC.

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Date:   Wed, 23 Oct 2019 16:04:26 -0700
From:   Anthony Steinhauser <asteinhauser@...gle.com>
To:     linux-kernel@...r.kernel.org
Cc:     Michael Ellerman <mpe@...erman.id.au>,
        Anthony Steinhauser <asteinhauser@...gle.com>
Subject: [PATCH] SYSFS reporting of L1TF on PowerPC.

L1TF affects PowerPC of the same range as Meltdown-US.
I tested it personally:
https://github.com/google/safeside/pull/52
and it is also admitted in the IBM report:
https://www.ibm.com/blogs/psirt/potential-impact-processors-power-family/
Similarly to Meltdown it is effectively mitigated by the rfi_flush.

Signed-off-by: Anthony Steinhauser <asteinhauser@...gle.com>
---
 arch/powerpc/kernel/security.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/arch/powerpc/kernel/security.c b/arch/powerpc/kernel/security.c
index 7cfcb294b11c..410232e79371 100644
--- a/arch/powerpc/kernel/security.c
+++ b/arch/powerpc/kernel/security.c
@@ -167,6 +167,18 @@ ssize_t cpu_show_meltdown(struct device *dev, struct device_attribute *attr, cha
 
 	return sprintf(buf, "Vulnerable\n");
 }
+
+ssize_t cpu_show_l1tf(struct device *dev, struct device_attribute *attr, char *buf)
+{
+	if (rfi_flush)
+		return sprintf(buf, "Mitigation: RFI Flush");
+
+	if (!security_ftr_enabled(SEC_FTR_L1D_FLUSH_HV) &&
+	    !security_ftr_enabled(SEC_FTR_L1D_FLUSH_PR))
+		return sprintf(buf, "Not affected\n");
+
+	return sprintf(buf, "Vulnerable\n");
+}
 #endif
 
 ssize_t cpu_show_spectre_v1(struct device *dev, struct device_attribute *attr, char *buf)
-- 
2.23.0.866.gb869b98d4c-goog