KVM/ARM updates for 4.10-rc4

- Fix for timer setup on VHE machines
 - Drop spurious warning when the timer races against
   the vcpu running again
 - Prevent a vgic deadlock when the initialization fails
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Merge tag 'kvm-arm-for-4.10-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm

KVM/ARM updates for 4.10-rc4

- Fix for timer setup on VHE machines
- Drop spurious warning when the timer races against
  the vcpu running again
- Prevent a vgic deadlock when the initialization fails

arch/arm/include/asm/virt.h

@@ -80,6 +80,11 @@ static inline bool is_kernel_in_hyp_mode(void)
 	return false;
 }
 
+static inline bool has_vhe(void)
+{
+	return false;
+}
+
 /* The section containing the hypervisor idmap text */
 extern char __hyp_idmap_text_start[];
 extern char __hyp_idmap_text_end[];

arch/arm/kvm/arm.c

@@ -1099,6 +1099,9 @@ static void cpu_init_hyp_mode(void *dummy)
 	__cpu_init_hyp_mode(pgd_ptr, hyp_stack_ptr, vector_ptr);
 	__cpu_init_stage2();
 
+	if (is_kernel_in_hyp_mode())
+		kvm_timer_init_vhe();
+
 	kvm_arm_init_debug();
 }
 

arch/arm64/include/asm/virt.h

@@ -47,6 +47,7 @@
 #include <asm/ptrace.h>
 #include <asm/sections.h>
 #include <asm/sysreg.h>
+#include <asm/cpufeature.h>
 
 /*
  * __boot_cpu_mode records what mode CPUs were booted in.
@@ -80,6 +81,14 @@ static inline bool is_kernel_in_hyp_mode(void)
 	return read_sysreg(CurrentEL) == CurrentEL_EL2;
 }
 
+static inline bool has_vhe(void)
+{
+	if (cpus_have_const_cap(ARM64_HAS_VIRT_HOST_EXTN))
+		return true;
+
+	return false;
+}
+
 #ifdef CONFIG_ARM64_VHE
 extern void verify_cpu_run_el(void);
 #else

include/kvm/arm_arch_timer.h

@@ -76,4 +76,5 @@ void kvm_timer_unschedule(struct kvm_vcpu *vcpu);
 
 void kvm_timer_vcpu_put(struct kvm_vcpu *vcpu);
 
+void kvm_timer_init_vhe(void);
 #endif

virt/kvm/arm/arch_timer.c

@@ -24,6 +24,7 @@
 
 #include <clocksource/arm_arch_timer.h>
 #include <asm/arch_timer.h>
+#include <asm/kvm_hyp.h>
 
 #include <kvm/arm_vgic.h>
 #include <kvm/arm_arch_timer.h>
@@ -89,9 +90,6 @@ static void kvm_timer_inject_irq_work(struct work_struct *work)
 	struct kvm_vcpu *vcpu;
 
 	vcpu = container_of(work, struct kvm_vcpu, arch.timer_cpu.expired);
-	vcpu->arch.timer_cpu.armed = false;
-
-	WARN_ON(!kvm_timer_should_fire(vcpu));
 
 	/*
 	 * If the vcpu is blocked we want to wake it up so that it will see
@@ -512,3 +510,25 @@ void kvm_timer_init(struct kvm *kvm)
 {
 	kvm->arch.timer.cntvoff = kvm_phys_timer_read();
 }
+
+/*
+ * On VHE system, we only need to configure trap on physical timer and counter
+ * accesses in EL0 and EL1 once, not for every world switch.
+ * The host kernel runs at EL2 with HCR_EL2.TGE == 1,
+ * and this makes those bits have no effect for the host kernel execution.
+ */
+void kvm_timer_init_vhe(void)
+{
+	/* When HCR_EL2.E2H ==1, EL1PCEN and EL1PCTEN are shifted by 10 */
+	u32 cnthctl_shift = 10;
+	u64 val;
+
+	/*
+	 * Disallow physical timer access for the guest.
+	 * Physical counter access is allowed.
+	 */
+	val = read_sysreg(cnthctl_el2);
+	val &= ~(CNTHCTL_EL1PCEN << cnthctl_shift);
+	val |= (CNTHCTL_EL1PCTEN << cnthctl_shift);
+	write_sysreg(val, cnthctl_el2);
+}

virt/kvm/arm/hyp/timer-sr.c

@@ -35,10 +35,16 @@ void __hyp_text __timer_save_state(struct kvm_vcpu *vcpu)
 	/* Disable the virtual timer */
 	write_sysreg_el0(0, cntv_ctl);
 
+	/*
+	 * We don't need to do this for VHE since the host kernel runs in EL2
+	 * with HCR_EL2.TGE ==1, which makes those bits have no impact.
+	 */
+	if (!has_vhe()) {
 		/* Allow physical timer/counter access for the host */
 		val = read_sysreg(cnthctl_el2);
 		val |= CNTHCTL_EL1PCTEN | CNTHCTL_EL1PCEN;
 		write_sysreg(val, cnthctl_el2);
+	}
 
 	/* Clear cntvoff for the host */
 	write_sysreg(0, cntvoff_el2);
@@ -50,6 +56,8 @@ void __hyp_text __timer_restore_state(struct kvm_vcpu *vcpu)
 	struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
 	u64 val;
 
+	/* Those bits are already configured at boot on VHE-system */
+	if (!has_vhe()) {
 		/*
 		 * Disallow physical timer access for the guest
 		 * Physical counter access is allowed
@@ -58,6 +66,7 @@ void __hyp_text __timer_restore_state(struct kvm_vcpu *vcpu)
 		val &= ~CNTHCTL_EL1PCEN;
 		val |= CNTHCTL_EL1PCTEN;
 		write_sysreg(val, cnthctl_el2);
+	}
 
 	if (timer->enabled) {
 		write_sysreg(kvm->arch.timer.cntvoff, cntvoff_el2);

virt/kvm/arm/vgic/vgic-init.c

@@ -268,15 +268,11 @@ static void kvm_vgic_dist_destroy(struct kvm *kvm)
 {
 	struct vgic_dist *dist = &kvm->arch.vgic;
 
-	mutex_lock(&kvm->lock);
-
 	dist->ready = false;
 	dist->initialized = false;
 
 	kfree(dist->spis);
 	dist->nr_spis = 0;
-
-	mutex_unlock(&kvm->lock);
 }
 
 void kvm_vgic_vcpu_destroy(struct kvm_vcpu *vcpu)
@@ -286,7 +282,8 @@ void kvm_vgic_vcpu_destroy(struct kvm_vcpu *vcpu)
 	INIT_LIST_HEAD(&vgic_cpu->ap_list_head);
 }
 
-void kvm_vgic_destroy(struct kvm *kvm)
+/* To be called with kvm->lock held */
+static void __kvm_vgic_destroy(struct kvm *kvm)
 {
 	struct kvm_vcpu *vcpu;
 	int i;
@@ -297,6 +294,13 @@ void kvm_vgic_destroy(struct kvm *kvm)
 		kvm_vgic_vcpu_destroy(vcpu);
 }
 
+void kvm_vgic_destroy(struct kvm *kvm)
+{
+	mutex_lock(&kvm->lock);
+	__kvm_vgic_destroy(kvm);
+	mutex_unlock(&kvm->lock);
+}
+
 /**
  * vgic_lazy_init: Lazy init is only allowed if the GIC exposed to the guest
  * is a GICv2. A GICv3 must be explicitly initialized by the guest using the
@@ -348,6 +352,10 @@ int kvm_vgic_map_resources(struct kvm *kvm)
 		ret = vgic_v2_map_resources(kvm);
 	else
 		ret = vgic_v3_map_resources(kvm);
+
+	if (ret)
+		__kvm_vgic_destroy(kvm);
+
 out:
 	mutex_unlock(&kvm->lock);
 	return ret;

virt/kvm/arm/vgic/vgic-v2.c

@@ -293,8 +293,6 @@ int vgic_v2_map_resources(struct kvm *kvm)
 	dist->ready = true;
 
 out:
-	if (ret)
-		kvm_vgic_destroy(kvm);
 	return ret;
 }
 

virt/kvm/arm/vgic/vgic-v3.c

@@ -302,8 +302,6 @@ int vgic_v3_map_resources(struct kvm *kvm)
 	dist->ready = true;
 
 out:
-	if (ret)
-		kvm_vgic_destroy(kvm);
 	return ret;
 }