[3.16.y-ckt stable] Patch "arm64: KVM: Fix HCR setting for 32bit guests" has been added to staging queue

[Luis Henriques]

This is a note to let you know that I have just added a patch titled

    arm64: KVM: Fix HCR setting for 32bit guests

to the linux-3.16.y-queue branch of the 3.16.y-ckt extended stable tree 
which can be found at:

    http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-3.16.y-queue

This patch is scheduled to be released in version 3.16.7-ckt12.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.16.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

>From 026f44213ac033202e0118193108c82cd3571ab9 Mon Sep 17 00:00:00 2001
From: Marc Zyngier <marc.zyngier at arm.com>
Date: Sun, 11 Jan 2015 14:10:11 +0100
Subject: arm64: KVM: Fix HCR setting for 32bit guests

commit 801f6772cecea6cfc7da61aa197716ab64db5f9e upstream.

Commit b856a59141b1 (arm/arm64: KVM: Reset the HCR on each vcpu
when resetting the vcpu) moved the init of the HCR register to
happen later in the init of a vcpu, but left out the fixup
done in kvm_reset_vcpu when preparing for a 32bit guest.

As a result, the 32bit guest is run as a 64bit guest, but the
rest of the kernel still manages it as a 32bit. Fun follows.

Moving the fixup to vcpu_reset_hcr solves the problem for good.

Signed-off-by: Marc Zyngier <marc.zyngier at arm.com>
Signed-off-by: Christoffer Dall <christoffer.dall at linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini at redhat.com>
Signed-off-by: Shannon Zhao <shannon.zhao at linaro.org>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 arch/arm64/include/asm/kvm_emulate.h | 2 ++
 arch/arm64/kvm/reset.c               | 1 -
 2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/include/asm/kvm_emulate.h b/arch/arm64/include/asm/kvm_emulate.h
index 681cb9080100..91f33c2051f2 100644
--- a/arch/arm64/include/asm/kvm_emulate.h
+++ b/arch/arm64/include/asm/kvm_emulate.h
@@ -41,6 +41,8 @@ void kvm_inject_pabt(struct kvm_vcpu *vcpu, unsigned long addr);
 static inline void vcpu_reset_hcr(struct kvm_vcpu *vcpu)
 {
 	vcpu->arch.hcr_el2 = HCR_GUEST_FLAGS;
+	if (test_bit(KVM_ARM_VCPU_EL1_32BIT, vcpu->arch.features))
+		vcpu->arch.hcr_el2 &= ~HCR_RW;
 }

 static inline unsigned long *vcpu_pc(const struct kvm_vcpu *vcpu)
diff --git a/arch/arm64/kvm/reset.c b/arch/arm64/kvm/reset.c
index 70a7816535cd..0b4326578985 100644
--- a/arch/arm64/kvm/reset.c
+++ b/arch/arm64/kvm/reset.c
@@ -90,7 +90,6 @@ int kvm_reset_vcpu(struct kvm_vcpu *vcpu)
 			if (!cpu_has_32bit_el1())
 				return -EINVAL;
 			cpu_reset = &default_regs_reset32;
-			vcpu->arch.hcr_el2 &= ~HCR_RW;
 		} else {
 			cpu_reset = &default_regs_reset;
 		}