Patch "KVM: arm: Restore banked registers and physical timer access on hyp_panic()" has been added to the 4.9-stable tree

[<gregkh@linuxfoundation.org>]

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

    KVM: arm: Restore banked registers and physical timer access on hyp_panic()

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:
     kvm-arm-restore-banked-registers-and-physical-timer-access-on-hyp_panic.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@vger.kernel.org> know about it.


>From foo@baz Mon Apr  9 17:09:24 CEST 2018
From: James Morse <james.morse@arm.com>
Date: Tue, 25 Apr 2017 18:02:44 +0100
Subject: KVM: arm: Restore banked registers and physical timer access on hyp_panic()

From: James Morse <james.morse@arm.com>


[ Upstream commit d2e19368848ce6065daa785efca26faed54732b6 ]

When KVM panics, it hurridly restores the host context and parachutes
into the host's panic() code. This looks like it was copied from arm64,
the 32bit KVM panic code needs to restore the host's banked registers
too.

At some point panic() touches the physical timer/counter, this will
trap back to HYP. If we're lucky, we panic again.

Add a __timer_save_state() call to KVMs hyp_panic() path, this saves the
guest registers and disables the traps for the host.

Fixes: c36b6db5f3e4 ("ARM: KVM: Add panic handling code")
Signed-off-by: James Morse <james.morse@arm.com>
Reviewed-by: Marc Zyngier <marc.zyngier@arm.com>
Reviewed-by: Christoffer Dall <cdall@linaro.org>
Signed-off-by: Christoffer Dall <cdall@linaro.org>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 arch/arm/kvm/hyp/switch.c |    2 ++
 1 file changed, 2 insertions(+)

--- a/arch/arm/kvm/hyp/switch.c
+++ b/arch/arm/kvm/hyp/switch.c
@@ -237,8 +237,10 @@ void __hyp_text __noreturn __hyp_panic(i
 
 		vcpu = (struct kvm_vcpu *)read_sysreg(HTPIDR);
 		host_ctxt = kern_hyp_va(vcpu->arch.host_cpu_context);
+		__timer_save_state(vcpu);
 		__deactivate_traps(vcpu);
 		__deactivate_vm(vcpu);
+		__banked_restore_state(host_ctxt);
 		__sysreg_restore_state(host_ctxt);
 	}
 


Patches currently in stable-queue which might be from james.morse@arm.com are

queue-4.9/kvm-arm-restore-banked-registers-and-physical-timer-access-on-hyp_panic.patch
queue-4.9/kvm-arm64-restore-host-physical-timer-access-on-hyp_panic.patch