From d02fa40d759ff9a53c93b10d8a4b591688982b26 Mon Sep 17 00:00:00 2001
From: Nicholas Piggin <npiggin@gmail.com>
Date: Mon, 3 May 2021 23:02:43 +1000
Subject: [PATCH] powerpc/powernv: Remove POWER9 PVR version check for entry
and uaccess flushes
References: bsc#1188885 ltc#193722 git-fixes
Patch-mainline: v5.17-rc1
Git-commit: d02fa40d759ff9a53c93b10d8a4b591688982b26
These aren't necessarily POWER9 only, and it's not to say some new
vulnerability may not get discovered on other processors for which
we would like the flexibility of having the workaround enabled by
firmware.
Remove the restriction that the workarounds only apply to POWER9.
However POWER7 and POWER8 are not affected, and they may not have
older firmware that does not advertise this, so clear these workarounds
manually.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: Joel Stanley <joel@jms.id.au>
[mpe: Incorporate changes from Nick, reword comment slightly.]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210503130243.891868-5-npiggin@gmail.com
Acked-by: Michal Suchanek <msuchanek@suse.de>
---
arch/powerpc/platforms/powernv/setup.c | 10 +++++++---
1 file changed, 7 insertions(+), 3 deletions(-)
diff --git a/arch/powerpc/platforms/powernv/setup.c b/arch/powerpc/platforms/powernv/setup.c
index ad56a54ac9c5..5ef6b8afb3d0 100644
--- a/arch/powerpc/platforms/powernv/setup.c
+++ b/arch/powerpc/platforms/powernv/setup.c
@@ -123,10 +123,14 @@ static void pnv_setup_security_mitigations(void)
}
/*
- * If we are non-Power9 bare metal, we don't need to flush on kernel
- * entry or after user access: they fix a P9 specific vulnerability.
+ * The issues addressed by the entry and uaccess flush don't affect P7
+ * or P8, so on bare metal disable them explicitly in case firmware does
+ * not include the features to disable them. POWER9 and newer processors
+ * should have the appropriate firmware flags.
*/
- if (!pvr_version_is(PVR_POWER9)) {
+ if (pvr_version_is(PVR_POWER7) || pvr_version_is(PVR_POWER7p) ||
+ pvr_version_is(PVR_POWER8E) || pvr_version_is(PVR_POWER8NVL) ||
+ pvr_version_is(PVR_POWER8)) {
security_ftr_clear(SEC_FTR_L1D_FLUSH_ENTRY);
security_ftr_clear(SEC_FTR_L1D_FLUSH_UACCESS);
}
--
2.35.3