Patch "KVM: arm64: Restore host physical timer access on hyp_panic()" has been added to the 4.9-stable tree

Patch "KVM: arm64: Restore host physical timer access on hyp_panic()" has been added to the 4.9-stable tree

[gregkh]

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

    KVM: arm64: Restore host 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-arm64-restore-host-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 18:02:45 +0100
Subject: KVM: arm64: Restore host physical timer access on hyp_panic()

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


[ Upstream commit e8ec032b182cd4841605de4fc297a8edffe55972 ]

When KVM panics, it hurridly restores the host context and parachutes
into the host's panic() code. At some point panic() touches the physical
timer/counter. Unless we are an arm64 system with VHE, this traps back
to EL2. 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: 53fd5b6487e4 ("arm64: KVM: Add panic handling")
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/arm64/kvm/hyp/switch.c |    1 +
 1 file changed, 1 insertion(+)

--- a/arch/arm64/kvm/hyp/switch.c
+++ b/arch/arm64/kvm/hyp/switch.c
@@ -404,6 +404,7 @@ void __hyp_text __noreturn __hyp_panic(v
 
 		vcpu = (struct kvm_vcpu *)read_sysreg(tpidr_el2);
 		host_ctxt = kern_hyp_va(vcpu->arch.host_cpu_context);
+		__timer_save_state(vcpu);
 		__deactivate_traps(vcpu);
 		__deactivate_vm(vcpu);
 		__sysreg_restore_host_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