arm/arm64: KVM: Reset the HCR on each vcpu when resetting the vcpu

When userspace resets the vcpu using KVM_ARM_VCPU_INIT, we should also
reset the HCR, because we now modify the HCR dynamically to
enable/disable trapping of guest accesses to the VM registers.

This is crucial for reboot of VMs working since otherwise we will not be
doing the necessary cache maintenance operations when faulting in pages
with the guest MMU off.

Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>

2 files changed, 5 insertions, 1 deletions

diff --git a/arch/arm64/include/asm/kvm_emulate.h b/arch/arm64/include/asm/kvm_emulate.h
index 5674a55b5518..8127e45e2637 100644
--- a/arch/arm64/include/asm/kvm_emulate.h
+++ b/arch/arm64/include/asm/kvm_emulate.h
@@ -38,6 +38,11 @@ void kvm_inject_undefined(struct kvm_vcpu *vcpu);
 void kvm_inject_dabt(struct kvm_vcpu *vcpu, unsigned long addr);
 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;
+}
+
 static inline unsigned long *vcpu_pc(const struct kvm_vcpu *vcpu)
 {
         return (unsigned long *)&vcpu_gp_regs(vcpu)->regs.pc;
diff --git a/arch/arm64/kvm/guest.c b/arch/arm64/kvm/guest.c
index 76794692c20b..84d5959ff874 100644
--- a/arch/arm64/kvm/guest.c
+++ b/arch/arm64/kvm/guest.c
@@ -38,7 +38,6 @@ struct kvm_stats_debugfs_item debugfs_entries[] = {
 
 int kvm_arch_vcpu_setup(struct kvm_vcpu *vcpu)
 {
-        vcpu->arch.hcr_el2 = HCR_GUEST_FLAGS;
         return 0;
 }