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Patch "arm64: KVM: VHE: Context switch MDSCR_EL1" has been added to the 4.7-stable tree

PATCH [email protected] 1 participant 1 message Aug 17, 2016

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This is a note to let you know that I've just added the patch titled

arm64: KVM: VHE: Context switch MDSCR_EL1

to the 4.7-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-vhe-context-switch-mdscr_el1.patch
and it can be found in the queue-4.7 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

Quoted 1 line

From 4c47eb1c18c38b755eb4894a6ca38f834de3ec23 Mon Sep 17 00:00:00 2001

From: Marc Zyngier <[email protected]>
Date: Tue, 19 Jul 2016 13:56:54 +0100
Subject: arm64: KVM: VHE: Context switch MDSCR_EL1
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

From: Marc Zyngier <[email protected]>

commit 4c47eb1c18c38b755eb4894a6ca38f834de3ec23 upstream.

The kprobe enablement work has uncovered that changes made by a guest to MDSCR_EL1 were propagated to the host when VHE was enabled, leading to unexpected exception being delivered.

Moving this register to the list of registers that are always context-switched fixes the issue.

Fixes 9c6c35683286 ("arm64: KVM: VHE: Split save/restore of registers shared between guest and host")
Reported-by Tirumalesh Chalamarla <[email protected]>
Tested-by Tirumalesh Chalamarla <[email protected]>
Signed-off-by Marc Zyngier <[email protected]>
Signed-off-by Radim Krčmář <[email protected]>
Signed-off-by Greg Kroah-Hartman <[email protected]>
---
 arch/arm64/kvm/hyp/sysreg-sr.c |    8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)
arch/arm64/kvm/hyp/sysreg-sr.c +4 -4
@@ -27,8 +27,8 @@ static void __hyp_text __sysreg_do_nothi
 /*
  * Non-VHE: Both host and guest must save everything.
  *
- * VHE: Host must save tpidr*_el[01], actlr_el1, sp0, pc, pstate, and
- * guest must save everything.
+ * VHE: Host must save tpidr*_el[01], actlr_el1, mdscr_el1, sp0, pc,
+ * pstate, and guest must save everything.
  */
 
 static void __hyp_text __sysreg_save_common_state(struct kvm_cpu_context *ctxt)

@@ -37,6 +37,7 @@ static void __hyp_text __sysreg_save_com
 	ctxt->sys_regs[TPIDR_EL0]	= read_sysreg(tpidr_el0);
 	ctxt->sys_regs[TPIDRRO_EL0]	= read_sysreg(tpidrro_el0);
 	ctxt->sys_regs[TPIDR_EL1]	= read_sysreg(tpidr_el1);
+	ctxt->sys_regs[MDSCR_EL1]	= read_sysreg(mdscr_el1);
 	ctxt->gp_regs.regs.sp		= read_sysreg(sp_el0);
 	ctxt->gp_regs.regs.pc		= read_sysreg_el2(elr);
 	ctxt->gp_regs.regs.pstate	= read_sysreg_el2(spsr);

@@ -61,7 +62,6 @@ static void __hyp_text __sysreg_save_sta
 	ctxt->sys_regs[AMAIR_EL1]	= read_sysreg_el1(amair);
 	ctxt->sys_regs[CNTKCTL_EL1]	= read_sysreg_el1(cntkctl);
 	ctxt->sys_regs[PAR_EL1]		= read_sysreg(par_el1);
-	ctxt->sys_regs[MDSCR_EL1]	= read_sysreg(mdscr_el1);
 
 	ctxt->gp_regs.sp_el1		= read_sysreg(sp_el1);
 	ctxt->gp_regs.elr_el1		= read_sysreg_el1(elr);

@@ -90,6 +90,7 @@ static void __hyp_text __sysreg_restore_
 	write_sysreg(ctxt->sys_regs[TPIDR_EL0],	  tpidr_el0);
 	write_sysreg(ctxt->sys_regs[TPIDRRO_EL0], tpidrro_el0);
 	write_sysreg(ctxt->sys_regs[TPIDR_EL1],	  tpidr_el1);
+	write_sysreg(ctxt->sys_regs[MDSCR_EL1],	  mdscr_el1);
 	write_sysreg(ctxt->gp_regs.regs.sp,	  sp_el0);
 	write_sysreg_el2(ctxt->gp_regs.regs.pc,	  elr);
 	write_sysreg_el2(ctxt->gp_regs.regs.pstate, spsr);

@@ -114,7 +115,6 @@ static void __hyp_text __sysreg_restore_
 	write_sysreg_el1(ctxt->sys_regs[AMAIR_EL1],	amair);
 	write_sysreg_el1(ctxt->sys_regs[CNTKCTL_EL1], 	cntkctl);
 	write_sysreg(ctxt->sys_regs[PAR_EL1],		par_el1);
-	write_sysreg(ctxt->sys_regs[MDSCR_EL1],		mdscr_el1);
 
 	write_sysreg(ctxt->gp_regs.sp_el1,		sp_el1);
 	write_sysreg_el1(ctxt->gp_regs.elr_el1,		elr);

Patches currently in stable-queue which might be from [email protected] are

queue-4.7/arm64-debug-unmask-pstate.d-earlier.patch queue-4.7/arm64-kvm-vhe-context-switch-mdscr_el1.patch