This is a note to let you know that I've just added the patch titled
arm64: KVM: Preserve RES1 bits in SCTLR_EL2
to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
arm64-kvm-preserve-res1-bits-in-sctlr_el2.patch
and it can be found in the queue-4.9 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From d68c1f7fd1b7148dab5fe658321d511998969f2d Mon Sep 17 00:00:00 2001
From: Marc Zyngier <marc.zyngier@xxxxxxx>
Date: Tue, 6 Jun 2017 19:08:33 +0100
Subject: arm64: KVM: Preserve RES1 bits in SCTLR_EL2
From: Marc Zyngier <marc.zyngier@xxxxxxx>
commit d68c1f7fd1b7148dab5fe658321d511998969f2d upstream.
__do_hyp_init has the rather bad habit of ignoring RES1 bits and
writing them back as zero. On a v8.0-8.2 CPU, this doesn't do anything
bad, but may end-up being pretty nasty on future revisions of the
architecture.
Let's preserve those bits so that we don't have to fix this later on.
Signed-off-by: Marc Zyngier <marc.zyngier@xxxxxxx>
Signed-off-by: Christoffer Dall <cdall@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/arm64/include/asm/sysreg.h | 4 ++++
arch/arm64/kvm/hyp-init.S | 10 ++++++----
2 files changed, 10 insertions(+), 4 deletions(-)
--- a/arch/arm64/include/asm/sysreg.h
+++ b/arch/arm64/include/asm/sysreg.h
@@ -94,6 +94,10 @@
#define SCTLR_ELx_A (1 << 1)
#define SCTLR_ELx_M 1
+#define SCTLR_EL2_RES1 ((1 << 4) | (1 << 5) | (1 << 11) | (1 << 16) | \
+ (1 << 16) | (1 << 18) | (1 << 22) | (1 << 23) | \
+ (1 << 28) | (1 << 29))
+
#define SCTLR_ELx_FLAGS (SCTLR_ELx_M | SCTLR_ELx_A | SCTLR_ELx_C | \
SCTLR_ELx_SA | SCTLR_ELx_I)
--- a/arch/arm64/kvm/hyp-init.S
+++ b/arch/arm64/kvm/hyp-init.S
@@ -102,10 +102,12 @@ __do_hyp_init:
tlbi alle2
dsb sy
- mrs x4, sctlr_el2
- and x4, x4, #SCTLR_ELx_EE // preserve endianness of EL2
- ldr x5, =SCTLR_ELx_FLAGS
- orr x4, x4, x5
+ /*
+ * Preserve all the RES1 bits while setting the default flags,
+ * as well as the EE bit on BE.
+ */
+ ldr x4, =(SCTLR_EL2_RES1 | SCTLR_ELx_FLAGS)
+CPU_BE( orr x4, x4, #SCTLR_ELx_EE)
msr sctlr_el2, x4
isb
Patches currently in stable-queue which might be from marc.zyngier@xxxxxxx are
queue-4.9/arm64-kvm-allow-unaligned-accesses-at-el2.patch
queue-4.9/arm-kvm-allow-unaligned-accesses-at-hyp.patch
queue-4.9/arm64-kvm-preserve-res1-bits-in-sctlr_el2.patch