[v4 0/4] arm64: kvm: reset hyp context for kexec

[v4 0/4] arm64: kvm: reset hyp context for kexec

[AKASHI Takahiro]

This patch set addresses KVM issue described in Geoff's kexec patch set[1].
See "Changes" below.
Initially, I used reboot notifier hook to shut down cpu cores, but in this
version, kvm cpu hotplug is implemented after Mark's comment.

I confirmed that it works with kexec under the following scenarios:
  - boot 1st kernel
  - run a guest OS
  - (stop a guest OS)
  - reboot 2nd kernel by kexec
  - run a guest OS

test target: MediaTek MT8173-EVB
version:     kernel v4.0-rc1 + Geoff's kexec v8 + Arn's patch[2]

But I didn't test other complicated scenarios with cpu hotplug.

On arm, Frediano[3] is no longer working on this issue as he left his
company. patch#4 is just a stub for arm.

Changes from v3:
* modified to use kvm cpu hotplug framework directly instead of reboot
  notifier hook

Changes from v2:
* modified kvm_virt_to_trampoline() macro to fix a page-alignment issue[4]

Changes from v1:
* modified kvm_cpu_reset() implementation:
    - define a macro to translate va to addr in trampoline
    - use __hyp_default_vectors instead of kvm_get_hyp_stub_vectors()
    - shuffle the arguments in __cpu_reset_hyp_mode()
    - optimize TLB flush operations
* changed a patch#2's name
* added a patch#5 to add stub code for arm

[1] http://lists.infradead.org/pipermail/kexec/2015-April/335533.html
[2] http://lists.infradead.org/pipermail/linux-arm-kernel/2015-March/334002.html
[3] http://lists.infradead.org/pipermail/linux-arm-kernel/2015-February/322231.html
[4] http://lists.infradead.org/pipermail/linux-arm-kernel/2015-March/334910.html


AKASHI Takahiro (4):
  arm64: kvm: add a cpu tear-down function
  arm64: kvm: add kvm cpu hotplug
  arm64: kvm: remove !KEXEC dependency
  arm: kvm: add stub implementation for kvm_cpu_reset()

 arch/arm/include/asm/kvm_asm.h    |    1 +
 arch/arm/include/asm/kvm_host.h   |   13 ++++++++++-
 arch/arm/include/asm/kvm_mmu.h    |    5 +++++
 arch/arm/kvm/arm.c                |   44 ++++++++++++++++++++++++++++---------
 arch/arm/kvm/init.S               |    6 +++++
 arch/arm/kvm/mmu.c                |    5 +++++
 arch/arm64/include/asm/kvm_asm.h  |    1 +
 arch/arm64/include/asm/kvm_host.h |   12 +++++++++-
 arch/arm64/include/asm/kvm_mmu.h  |    7 ++++++
 arch/arm64/include/asm/virt.h     |   11 ++++++++++
 arch/arm64/kvm/Kconfig            |    1 -
 arch/arm64/kvm/hyp-init.S         |   32 +++++++++++++++++++++++++++
 arch/arm64/kvm/hyp.S              |   16 +++++++++++---
 13 files changed, 138 insertions(+), 16 deletions(-)

-- 
1.7.9.5

[v4 1/4] arm64: kvm: add a cpu tear-down function

[AKASHI Takahiro]

Cpu must be put back into its initial state, at least, in the
following cases in order to shutdown the system and/or re-initialize cpus
later on:
1) kexec/kdump
2) cpu hotplug (offline)
3) removing kvm as a module

To address those issues in later patches, this patch adds a tear-down
function, kvm_cpu_reset(), that disables D-cache & MMU and restore a vector
table to the initial stub at EL2.

Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
---
 arch/arm/kvm/arm.c                |   15 +++++++++++++++
 arch/arm/kvm/mmu.c                |    5 +++++
 arch/arm64/include/asm/kvm_asm.h  |    1 +
 arch/arm64/include/asm/kvm_host.h |   11 +++++++++++
 arch/arm64/include/asm/kvm_mmu.h  |    7 +++++++
 arch/arm64/include/asm/virt.h     |   11 +++++++++++
 arch/arm64/kvm/hyp-init.S         |   32 ++++++++++++++++++++++++++++++++
 arch/arm64/kvm/hyp.S              |   16 +++++++++++++---
 8 files changed, 95 insertions(+), 3 deletions(-)

diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c
index 07e7eb1..251ab9e 100644
--- a/arch/arm/kvm/arm.c
+++ b/arch/arm/kvm/arm.c
@@ -897,6 +897,21 @@ static void cpu_init_hyp_mode(void *dummy)
 	__cpu_init_hyp_mode(boot_pgd_ptr, pgd_ptr, hyp_stack_ptr, vector_ptr);
 }
 
+static void kvm_cpu_reset(void *dummy)
+{
+	phys_addr_t boot_pgd_ptr;
+	phys_addr_t phys_idmap_start;
+
+	if (__hyp_get_vectors() == hyp_default_vectors)
+		return;
+
+	boot_pgd_ptr = kvm_mmu_get_boot_httbr();
+	phys_idmap_start = kvm_get_idmap_start();
+	__cpu_reset_hyp_mode(boot_pgd_ptr, phys_idmap_start,
+			     hyp_default_vectors,
+			     kvm_virt_to_trampoline(__kvm_hyp_reset));
+}
+
 static int hyp_init_cpu_notify(struct notifier_block *self,
 			       unsigned long action, void *cpu)
 {
diff --git a/arch/arm/kvm/mmu.c b/arch/arm/kvm/mmu.c
index 3e6859b..3631a37 100644
--- a/arch/arm/kvm/mmu.c
+++ b/arch/arm/kvm/mmu.c
@@ -1490,6 +1490,11 @@ phys_addr_t kvm_get_idmap_vector(void)
 	return hyp_idmap_vector;
 }
 
+phys_addr_t kvm_get_idmap_start(void)
+{
+	return hyp_idmap_start;
+}
+
 int kvm_mmu_init(void)
 {
 	int err;
diff --git a/arch/arm64/include/asm/kvm_asm.h b/arch/arm64/include/asm/kvm_asm.h
index 4f7310f..f1c16e2 100644
--- a/arch/arm64/include/asm/kvm_asm.h
+++ b/arch/arm64/include/asm/kvm_asm.h
@@ -118,6 +118,7 @@ struct kvm_vcpu;
 
 extern char __kvm_hyp_init[];
 extern char __kvm_hyp_init_end[];
+extern char __kvm_hyp_reset[];
 
 extern char __kvm_hyp_vector[];
 
diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index 8ac3c70..6a8da9c 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -199,6 +199,8 @@ struct kvm_vcpu *kvm_arm_get_running_vcpu(void);
 struct kvm_vcpu * __percpu *kvm_get_running_vcpus(void);
 
 u64 kvm_call_hyp(void *hypfn, ...);
+void kvm_call_reset(phys_addr_t boot_pgd_ptr, phys_addr_t phys_idmap_start,
+		    unsigned long stub_vector_ptr, unsigned long reset_func);
 void force_vm_exit(const cpumask_t *mask);
 void kvm_mmu_wp_memory_region(struct kvm *kvm, int slot);
 
@@ -223,6 +225,15 @@ static inline void __cpu_init_hyp_mode(phys_addr_t boot_pgd_ptr,
 		     hyp_stack_ptr, vector_ptr);
 }
 
+static inline void __cpu_reset_hyp_mode(phys_addr_t boot_pgd_ptr,
+					phys_addr_t phys_idmap_start,
+					unsigned long stub_vector_ptr,
+					unsigned long reset_func)
+{
+	kvm_call_reset(boot_pgd_ptr, phys_idmap_start, stub_vector_ptr,
+		       reset_func);
+}
+
 struct vgic_sr_vectors {
 	void	*save_vgic;
 	void	*restore_vgic;
diff --git a/arch/arm64/include/asm/kvm_mmu.h b/arch/arm64/include/asm/kvm_mmu.h
index 6458b53..facfd6d 100644
--- a/arch/arm64/include/asm/kvm_mmu.h
+++ b/arch/arm64/include/asm/kvm_mmu.h
@@ -96,6 +96,7 @@ void kvm_mmu_free_memory_caches(struct kvm_vcpu *vcpu);
 phys_addr_t kvm_mmu_get_httbr(void);
 phys_addr_t kvm_mmu_get_boot_httbr(void);
 phys_addr_t kvm_get_idmap_vector(void);
+phys_addr_t kvm_get_idmap_start(void);
 int kvm_mmu_init(void);
 void kvm_clear_hyp_idmap(void);
 
@@ -305,5 +306,11 @@ static inline void __kvm_flush_dcache_pud(pud_t pud)
 void kvm_set_way_flush(struct kvm_vcpu *vcpu);
 void kvm_toggle_cache(struct kvm_vcpu *vcpu, bool was_enabled);
 
+extern char __hyp_idmap_text_start[];
+#define kvm_virt_to_trampoline(x)	\
+		(TRAMPOLINE_VA		\
+		+ ((unsigned long)(x)	\
+		  - ((unsigned long)__hyp_idmap_text_start & PAGE_MASK)))
+
 #endif /* __ASSEMBLY__ */
 #endif /* __ARM64_KVM_MMU_H__ */
diff --git a/arch/arm64/include/asm/virt.h b/arch/arm64/include/asm/virt.h
index 3070096..7fcd087 100644
--- a/arch/arm64/include/asm/virt.h
+++ b/arch/arm64/include/asm/virt.h
@@ -61,6 +61,17 @@
 #define BOOT_CPU_MODE_EL1	(0xe11)
 #define BOOT_CPU_MODE_EL2	(0xe12)
 
+/*
+ * HVC_RESET - Reset cpu in EL2 to initial state.
+ *
+ * @x0: entry address in trampoline code in va
+ * @x1: identical mapping page table in pa
+ * @x2: start address of identical mapping in pa
+ * @x3: initial stub vector in pa
+ */
+
+#define HVC_RESET 5
+
 #ifndef __ASSEMBLY__
 
 /*
diff --git a/arch/arm64/kvm/hyp-init.S b/arch/arm64/kvm/hyp-init.S
index c319116..2614cfc 100644
--- a/arch/arm64/kvm/hyp-init.S
+++ b/arch/arm64/kvm/hyp-init.S
@@ -115,6 +115,38 @@ target: /* We're now in the trampoline code, switch page tables */
 	eret
 ENDPROC(__kvm_hyp_init)
 
+	/*
+	 * x0: HYP boot pgd
+	 * x1: HYP phys_idmap_start
+	 * x2: HYP stub vectors
+	 */
+ENTRY(__kvm_hyp_reset)
+	/* We're in trampoline code in VA, switch back to boot page tables */
+	msr	ttbr0_el2, x0
+	isb
+
+	/* Invalidate the old TLBs */
+	tlbi	alle2
+	dsb	sy
+
+	/* Branch into PA space */
+	adr	x0, 1f
+	bfi	x1, x0, #0, #PAGE_SHIFT
+	br	x1
+
+	/* We're now in idmap, disable MMU */
+1:	mrs	x0, sctlr_el2
+	ldr	x1, =SCTLR_EL2_FLAGS
+	bic	x0, x0, x1		// Clear SCTL_M and etc
+	msr	sctlr_el2, x0
+	isb
+
+	/* Install stub vectors */
+	msr	vbar_el2, x2
+
+	eret
+ENDPROC(__kvm_hyp_reset)
+
 	.ltorg
 
 	.popsection
diff --git a/arch/arm64/kvm/hyp.S b/arch/arm64/kvm/hyp.S
index fd085ec..7c3bdee 100644
--- a/arch/arm64/kvm/hyp.S
+++ b/arch/arm64/kvm/hyp.S
@@ -1136,6 +1136,11 @@ ENTRY(kvm_call_hyp)
 	ret
 ENDPROC(kvm_call_hyp)
 
+ENTRY(kvm_call_reset)
+	hvc	#HVC_RESET
+	ret
+ENDPROC(kvm_call_reset)
+
 .macro invalid_vector	label, target
 	.align	2
 \label:
@@ -1179,10 +1184,14 @@ el1_sync:					// Guest trapped into EL2
 	cmp	x18, #HVC_GET_VECTORS
 	b.ne	1f
 	mrs	x0, vbar_el2
-	b	2f
+	b	3f
 
-1:	/* Default to HVC_CALL_HYP. */
+	/* jump into trampoline code */
+1:	cmp	x18, #HVC_RESET
+	b.ne	2f
+	br	x3				// no return
 
+2:	/* Default to HVC_CALL_HYP. */
 	push	lr, xzr
 
 	/*
@@ -1196,7 +1205,8 @@ el1_sync:					// Guest trapped into EL2
 	blr	lr
 
 	pop	lr, xzr
-2:	eret
+
+3:	eret
 
 el1_trap:
 	/*
-- 
1.7.9.5

[v4 2/4] arm64: kvm: add kvm cpu hotplug

[AKASHI Takahiro]

This patch allows cpu cores to be up and down by adding
kvm_arch_hardware_enable/isable(). This way, especially in kexec case,
cores are reset to initial states and kexec can gracefully shutdown the
system and reboot a new kernel from EL2.

Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
---
 arch/arm/include/asm/kvm_host.h   |    1 -
 arch/arm/kvm/arm.c                |   29 +++++++++++++++++++----------
 arch/arm64/include/asm/kvm_host.h |    1 -
 3 files changed, 19 insertions(+), 12 deletions(-)

diff --git a/arch/arm/include/asm/kvm_host.h b/arch/arm/include/asm/kvm_host.h
index 41008cd..ca97764 100644
--- a/arch/arm/include/asm/kvm_host.h
+++ b/arch/arm/include/asm/kvm_host.h
@@ -237,7 +237,6 @@ void kvm_mmu_wp_memory_region(struct kvm *kvm, int slot);
 
 struct kvm_vcpu *kvm_mpidr_to_vcpu(struct kvm *kvm, unsigned long mpidr);
 
-static inline void kvm_arch_hardware_disable(void) {}
 static inline void kvm_arch_hardware_unsetup(void) {}
 static inline void kvm_arch_sync_events(struct kvm *kvm) {}
 static inline void kvm_arch_vcpu_uninit(struct kvm_vcpu *vcpu) {}
diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c
index 251ab9e..e989925 100644
--- a/arch/arm/kvm/arm.c
+++ b/arch/arm/kvm/arm.c
@@ -87,11 +87,6 @@ struct kvm_vcpu * __percpu *kvm_get_running_vcpus(void)
 	return &kvm_arm_running_vcpu;
 }
 
-int kvm_arch_hardware_enable(void)
-{
-	return 0;
-}
-
 int kvm_arch_vcpu_should_kick(struct kvm_vcpu *vcpu)
 {
 	return kvm_vcpu_exiting_guest_mode(vcpu) == IN_GUEST_MODE;
@@ -885,6 +880,9 @@ static void cpu_init_hyp_mode(void *dummy)
 	unsigned long stack_page;
 	unsigned long vector_ptr;
 
+	if (__hyp_get_vectors() != hyp_default_vectors)
+		return;
+
 	/* Switch from the HYP stub to our own HYP init vector */
 	__hyp_set_vectors(kvm_get_idmap_vector());
 
@@ -921,6 +919,10 @@ static int hyp_init_cpu_notify(struct notifier_block *self,
 		if (__hyp_get_vectors() == hyp_default_vectors)
 			cpu_init_hyp_mode(NULL);
 		break;
+	case CPU_DYING:
+	case CPU_DYING_FROZEN:
+		kvm_cpu_reset(NULL);
+		break;
 	}
 
 	return NOTIFY_OK;
@@ -936,6 +938,7 @@ static int hyp_init_cpu_pm_notifier(struct notifier_block *self,
 				    void *v)
 {
 	if (cmd == CPU_PM_EXIT &&
+	    kvm_arm_get_running_vcpu() &&
 	    __hyp_get_vectors() == hyp_default_vectors) {
 		cpu_init_hyp_mode(NULL);
 		return NOTIFY_OK;
@@ -1039,11 +1042,6 @@ static int init_hyp_mode(void)
 	}
 
 	/*
-	 * Execute the init code on each CPU.
-	 */
-	on_each_cpu(cpu_init_hyp_mode, NULL, 1);
-
-	/*
 	 * Init HYP view of VGIC
 	 */
 	err = kvm_vgic_hyp_init();
@@ -1144,6 +1142,17 @@ out_err:
 	return err;
 }
 
+int kvm_arch_hardware_enable(void)
+{
+	cpu_init_hyp_mode(NULL);
+	return 0;
+}
+
+void kvm_arch_hardware_disable(void)
+{
+	kvm_cpu_reset(NULL);
+}
+
 /* NOP: Compiling as a module not supported */
 void kvm_arch_exit(void)
 {
diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index 6a8da9c..831e6a4 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -262,7 +262,6 @@ static inline void vgic_arch_setup(const struct vgic_params *vgic)
 	}
 }
 
-static inline void kvm_arch_hardware_disable(void) {}
 static inline void kvm_arch_hardware_unsetup(void) {}
 static inline void kvm_arch_sync_events(struct kvm *kvm) {}
 static inline void kvm_arch_vcpu_uninit(struct kvm_vcpu *vcpu) {}
-- 
1.7.9.5

[v4 3/4] arm64: kvm: remove !KEXEC dependency

[AKASHI Takahiro]

By indroducing cpu kvm hotplug, this dependency is not needed any more.

Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
---
 arch/arm64/kvm/Kconfig |    1 -
 1 file changed, 1 deletion(-)

diff --git a/arch/arm64/kvm/Kconfig b/arch/arm64/kvm/Kconfig
index 30ae7a7..f5590c8 100644
--- a/arch/arm64/kvm/Kconfig
+++ b/arch/arm64/kvm/Kconfig
@@ -18,7 +18,6 @@ if VIRTUALIZATION
 
 config KVM
 	bool "Kernel-based Virtual Machine (KVM) support"
-	depends on !KEXEC
 	select MMU_NOTIFIER
 	select PREEMPT_NOTIFIERS
 	select ANON_INODES
-- 
1.7.9.5

[v4 4/4] arm: kvm: add stub implementation for kvm_cpu_reset()

[AKASHI Takahiro]

Just to avoid compiling errors on arm.

Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
---
 arch/arm/include/asm/kvm_asm.h  |    1 +
 arch/arm/include/asm/kvm_host.h |   12 ++++++++++++
 arch/arm/include/asm/kvm_mmu.h  |    5 +++++
 arch/arm/kvm/init.S             |    6 ++++++
 4 files changed, 24 insertions(+)

diff --git a/arch/arm/include/asm/kvm_asm.h b/arch/arm/include/asm/kvm_asm.h
index 25410b2..462babf 100644
--- a/arch/arm/include/asm/kvm_asm.h
+++ b/arch/arm/include/asm/kvm_asm.h
@@ -85,6 +85,7 @@ struct kvm_vcpu;
 
 extern char __kvm_hyp_init[];
 extern char __kvm_hyp_init_end[];
+extern char __kvm_hyp_reset[];
 
 extern char __kvm_hyp_exit[];
 extern char __kvm_hyp_exit_end[];
diff --git a/arch/arm/include/asm/kvm_host.h b/arch/arm/include/asm/kvm_host.h
index ca97764..6d38134 100644
--- a/arch/arm/include/asm/kvm_host.h
+++ b/arch/arm/include/asm/kvm_host.h
@@ -220,6 +220,18 @@ static inline void __cpu_init_hyp_mode(phys_addr_t boot_pgd_ptr,
 	kvm_call_hyp((void*)hyp_stack_ptr, vector_ptr, pgd_ptr);
 }
 
+static inline void __cpu_reset_hyp_mode(phys_addr_t boot_pgd_ptr,
+					phys_addr_t phys_idmap_start,
+					unsigned long stub_vector_ptr,
+					unsigned long reset_func)
+{
+	/*
+	 * TODO
+	 * kvm_call_reset(boot_pgd_ptr, phys_idmap_start, stub_vector_ptr,
+	 *		  reset_func);
+	 */
+}
+
 static inline int kvm_arch_dev_ioctl_check_extension(long ext)
 {
 	return 0;
diff --git a/arch/arm/include/asm/kvm_mmu.h b/arch/arm/include/asm/kvm_mmu.h
index 37ca2a4..d85bcd1 100644
--- a/arch/arm/include/asm/kvm_mmu.h
+++ b/arch/arm/include/asm/kvm_mmu.h
@@ -66,6 +66,7 @@ void kvm_mmu_free_memory_caches(struct kvm_vcpu *vcpu);
 phys_addr_t kvm_mmu_get_httbr(void);
 phys_addr_t kvm_mmu_get_boot_httbr(void);
 phys_addr_t kvm_get_idmap_vector(void);
+phys_addr_t kvm_get_idmap_start(void);
 int kvm_mmu_init(void);
 void kvm_clear_hyp_idmap(void);
 
@@ -270,6 +271,10 @@ static inline void __kvm_flush_dcache_pud(pud_t pud)
 void kvm_set_way_flush(struct kvm_vcpu *vcpu);
 void kvm_toggle_cache(struct kvm_vcpu *vcpu, bool was_enabled);
 
+extern char __hyp_idmap_text_start[];
+#define kvm_virt_to_trampoline(x)       \
+			(TRAMPOLINE_VA + ((x) - __hyp_idmap_text_start))
+
 #endif	/* !__ASSEMBLY__ */
 
 #endif /* __ARM_KVM_MMU_H__ */
diff --git a/arch/arm/kvm/init.S b/arch/arm/kvm/init.S
index 3988e72..9178c9a 100644
--- a/arch/arm/kvm/init.S
+++ b/arch/arm/kvm/init.S
@@ -156,4 +156,10 @@ target:	@ We're now in the trampoline code, switch page tables
 	.globl __kvm_hyp_init_end
 __kvm_hyp_init_end:
 
+	.globl __kvm_hyp_reset
+__kvm_hyp_reset:
+	@ TODO
+
+	eret
+
 	.popsection
-- 
1.7.9.5

[v4 1/4] arm64: kvm: add a cpu tear-down function

[Marc Zyngier]

Hi Takahiro,

On 08/05/15 02:18, AKASHI Takahiro wrote:
> Cpu must be put back into its initial state, at least, in the
> following cases in order to shutdown the system and/or re-initialize cpus
> later on:
> 1) kexec/kdump
> 2) cpu hotplug (offline)
> 3) removing kvm as a module
> 
> To address those issues in later patches, this patch adds a tear-down
> function, kvm_cpu_reset(), that disables D-cache & MMU and restore a vector
> table to the initial stub at EL2.
> 
> Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
> ---
>  arch/arm/kvm/arm.c                |   15 +++++++++++++++
>  arch/arm/kvm/mmu.c                |    5 +++++
>  arch/arm64/include/asm/kvm_asm.h  |    1 +
>  arch/arm64/include/asm/kvm_host.h |   11 +++++++++++
>  arch/arm64/include/asm/kvm_mmu.h  |    7 +++++++
>  arch/arm64/include/asm/virt.h     |   11 +++++++++++
>  arch/arm64/kvm/hyp-init.S         |   32 ++++++++++++++++++++++++++++++++
>  arch/arm64/kvm/hyp.S              |   16 +++++++++++++---
>  8 files changed, 95 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c
> index 07e7eb1..251ab9e 100644
> --- a/arch/arm/kvm/arm.c
> +++ b/arch/arm/kvm/arm.c
> @@ -897,6 +897,21 @@ static void cpu_init_hyp_mode(void *dummy)
>  	__cpu_init_hyp_mode(boot_pgd_ptr, pgd_ptr, hyp_stack_ptr, vector_ptr);
>  }
>  
> +static void kvm_cpu_reset(void *dummy)

It looks like you can entirely loose the "dummy" parameter. The only
reason some function have this is when they are used from an IPI call.

> +{
> +	phys_addr_t boot_pgd_ptr;
> +	phys_addr_t phys_idmap_start;
> +
> +	if (__hyp_get_vectors() == hyp_default_vectors)
> +		return;
> +
> +	boot_pgd_ptr = kvm_mmu_get_boot_httbr();
> +	phys_idmap_start = kvm_get_idmap_start();
> +	__cpu_reset_hyp_mode(boot_pgd_ptr, phys_idmap_start,
> +			     hyp_default_vectors,
> +			     kvm_virt_to_trampoline(__kvm_hyp_reset));
> +}
> +
>  static int hyp_init_cpu_notify(struct notifier_block *self,
>  			       unsigned long action, void *cpu)
>  {
> diff --git a/arch/arm/kvm/mmu.c b/arch/arm/kvm/mmu.c
> index 3e6859b..3631a37 100644
> --- a/arch/arm/kvm/mmu.c
> +++ b/arch/arm/kvm/mmu.c
> @@ -1490,6 +1490,11 @@ phys_addr_t kvm_get_idmap_vector(void)
>  	return hyp_idmap_vector;
>  }
>  
> +phys_addr_t kvm_get_idmap_start(void)
> +{
> +	return hyp_idmap_start;
> +}
> +
>  int kvm_mmu_init(void)
>  {
>  	int err;
> diff --git a/arch/arm64/include/asm/kvm_asm.h b/arch/arm64/include/asm/kvm_asm.h
> index 4f7310f..f1c16e2 100644
> --- a/arch/arm64/include/asm/kvm_asm.h
> +++ b/arch/arm64/include/asm/kvm_asm.h
> @@ -118,6 +118,7 @@ struct kvm_vcpu;
>  
>  extern char __kvm_hyp_init[];
>  extern char __kvm_hyp_init_end[];
> +extern char __kvm_hyp_reset[];
>  
>  extern char __kvm_hyp_vector[];
>  
> diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
> index 8ac3c70..6a8da9c 100644
> --- a/arch/arm64/include/asm/kvm_host.h
> +++ b/arch/arm64/include/asm/kvm_host.h
> @@ -199,6 +199,8 @@ struct kvm_vcpu *kvm_arm_get_running_vcpu(void);
>  struct kvm_vcpu * __percpu *kvm_get_running_vcpus(void);
>  
>  u64 kvm_call_hyp(void *hypfn, ...);
> +void kvm_call_reset(phys_addr_t boot_pgd_ptr, phys_addr_t phys_idmap_start,
> +		    unsigned long stub_vector_ptr, unsigned long reset_func);
>  void force_vm_exit(const cpumask_t *mask);
>  void kvm_mmu_wp_memory_region(struct kvm *kvm, int slot);
>  
> @@ -223,6 +225,15 @@ static inline void __cpu_init_hyp_mode(phys_addr_t boot_pgd_ptr,
>  		     hyp_stack_ptr, vector_ptr);
>  }
>  
> +static inline void __cpu_reset_hyp_mode(phys_addr_t boot_pgd_ptr,
> +					phys_addr_t phys_idmap_start,
> +					unsigned long stub_vector_ptr,
> +					unsigned long reset_func)
> +{
> +	kvm_call_reset(boot_pgd_ptr, phys_idmap_start, stub_vector_ptr,
> +		       reset_func);
> +}
> +
>  struct vgic_sr_vectors {
>  	void	*save_vgic;
>  	void	*restore_vgic;
> diff --git a/arch/arm64/include/asm/kvm_mmu.h b/arch/arm64/include/asm/kvm_mmu.h
> index 6458b53..facfd6d 100644
> --- a/arch/arm64/include/asm/kvm_mmu.h
> +++ b/arch/arm64/include/asm/kvm_mmu.h
> @@ -96,6 +96,7 @@ void kvm_mmu_free_memory_caches(struct kvm_vcpu *vcpu);
>  phys_addr_t kvm_mmu_get_httbr(void);
>  phys_addr_t kvm_mmu_get_boot_httbr(void);
>  phys_addr_t kvm_get_idmap_vector(void);
> +phys_addr_t kvm_get_idmap_start(void);
>  int kvm_mmu_init(void);
>  void kvm_clear_hyp_idmap(void);
>  
> @@ -305,5 +306,11 @@ static inline void __kvm_flush_dcache_pud(pud_t pud)
>  void kvm_set_way_flush(struct kvm_vcpu *vcpu);
>  void kvm_toggle_cache(struct kvm_vcpu *vcpu, bool was_enabled);
>  
> +extern char __hyp_idmap_text_start[];

If you're defining it here, then it worth considering removing the
similar declaration from mmu.c.

> +#define kvm_virt_to_trampoline(x)	\
> +		(TRAMPOLINE_VA		\
> +		+ ((unsigned long)(x)	\
> +		  - ((unsigned long)__hyp_idmap_text_start & PAGE_MASK)))
> +
>  #endif /* __ASSEMBLY__ */
>  #endif /* __ARM64_KVM_MMU_H__ */
> diff --git a/arch/arm64/include/asm/virt.h b/arch/arm64/include/asm/virt.h
> index 3070096..7fcd087 100644
> --- a/arch/arm64/include/asm/virt.h
> +++ b/arch/arm64/include/asm/virt.h
> @@ -61,6 +61,17 @@
>  #define BOOT_CPU_MODE_EL1	(0xe11)
>  #define BOOT_CPU_MODE_EL2	(0xe12)
>  
> +/*
> + * HVC_RESET - Reset cpu in EL2 to initial state.
> + *
> + * @x0: entry address in trampoline code in va
> + * @x1: identical mapping page table in pa
> + * @x2: start address of identical mapping in pa
> + * @x3: initial stub vector in pa
> + */
> +
> +#define HVC_RESET 5
> +
>  #ifndef __ASSEMBLY__
>  
>  /*
> diff --git a/arch/arm64/kvm/hyp-init.S b/arch/arm64/kvm/hyp-init.S
> index c319116..2614cfc 100644
> --- a/arch/arm64/kvm/hyp-init.S
> +++ b/arch/arm64/kvm/hyp-init.S
> @@ -115,6 +115,38 @@ target: /* We're now in the trampoline code, switch page tables */
>  	eret
>  ENDPROC(__kvm_hyp_init)
>  
> +	/*
> +	 * x0: HYP boot pgd
> +	 * x1: HYP phys_idmap_start
> +	 * x2: HYP stub vectors
> +	 */
> +ENTRY(__kvm_hyp_reset)
> +	/* We're in trampoline code in VA, switch back to boot page tables */
> +	msr	ttbr0_el2, x0
> +	isb
> +
> +	/* Invalidate the old TLBs */
> +	tlbi	alle2
> +	dsb	sy
> +
> +	/* Branch into PA space */
> +	adr	x0, 1f
> +	bfi	x1, x0, #0, #PAGE_SHIFT
> +	br	x1
> +
> +	/* We're now in idmap, disable MMU */
> +1:	mrs	x0, sctlr_el2
> +	ldr	x1, =SCTLR_EL2_FLAGS
> +	bic	x0, x0, x1		// Clear SCTL_M and etc
> +	msr	sctlr_el2, x0
> +	isb
> +
> +	/* Install stub vectors */
> +	msr	vbar_el2, x2

Instead of using a parameter, can't you just do

	adr	x2, __hyp_stub_vectors
	msr	vbar_el2, x2

? I can't imagine a case where we don't want this behaviour, and this
would slightly simplify the calling convention.

> +
> +	eret
> +ENDPROC(__kvm_hyp_reset)
> +
>  	.ltorg
>  
>  	.popsection
> diff --git a/arch/arm64/kvm/hyp.S b/arch/arm64/kvm/hyp.S
> index fd085ec..7c3bdee 100644
> --- a/arch/arm64/kvm/hyp.S
> +++ b/arch/arm64/kvm/hyp.S
> @@ -1136,6 +1136,11 @@ ENTRY(kvm_call_hyp)
>  	ret
>  ENDPROC(kvm_call_hyp)
>  
> +ENTRY(kvm_call_reset)
> +	hvc	#HVC_RESET
> +	ret
> +ENDPROC(kvm_call_reset)
> +
>  .macro invalid_vector	label, target
>  	.align	2
>  \label:
> @@ -1179,10 +1184,14 @@ el1_sync:					// Guest trapped into EL2
>  	cmp	x18, #HVC_GET_VECTORS
>  	b.ne	1f
>  	mrs	x0, vbar_el2
> -	b	2f
> +	b	3f

How about renaming this to something like "do_eret" once and for all so
that we stop this dance each time someone adds a new entry point?
>  
> -1:	/* Default to HVC_CALL_HYP. */
> +	/* jump into trampoline code */
> +1:	cmp	x18, #HVC_RESET
> +	b.ne	2f
> +	br	x3				// no return

Same here. If we're always jumping to the trampoline code, why do we
have to pass it as a parameter?

>  
> +2:	/* Default to HVC_CALL_HYP. */
>  	push	lr, xzr
>  
>  	/*
> @@ -1196,7 +1205,8 @@ el1_sync:					// Guest trapped into EL2
>  	blr	lr
>  
>  	pop	lr, xzr
> -2:	eret
> +
> +3:	eret
>  
>  el1_trap:
>  	/*
> 

Thanks,

	M.
-- 
Jazz is not dead. It just smells funny...

[v4 2/4] arm64: kvm: add kvm cpu hotplug

[Marc Zyngier]

On 08/05/15 02:18, AKASHI Takahiro wrote:
> This patch allows cpu cores to be up and down by adding
> kvm_arch_hardware_enable/isable(). This way, especially in kexec case,
> cores are reset to initial states and kexec can gracefully shutdown the
> system and reboot a new kernel from EL2.
> 
> Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
> ---
>  arch/arm/include/asm/kvm_host.h   |    1 -
>  arch/arm/kvm/arm.c                |   29 +++++++++++++++++++----------
>  arch/arm64/include/asm/kvm_host.h |    1 -
>  3 files changed, 19 insertions(+), 12 deletions(-)
> 
> diff --git a/arch/arm/include/asm/kvm_host.h b/arch/arm/include/asm/kvm_host.h
> index 41008cd..ca97764 100644
> --- a/arch/arm/include/asm/kvm_host.h
> +++ b/arch/arm/include/asm/kvm_host.h
> @@ -237,7 +237,6 @@ void kvm_mmu_wp_memory_region(struct kvm *kvm, int slot);
>  
>  struct kvm_vcpu *kvm_mpidr_to_vcpu(struct kvm *kvm, unsigned long mpidr);
>  
> -static inline void kvm_arch_hardware_disable(void) {}
>  static inline void kvm_arch_hardware_unsetup(void) {}
>  static inline void kvm_arch_sync_events(struct kvm *kvm) {}
>  static inline void kvm_arch_vcpu_uninit(struct kvm_vcpu *vcpu) {}
> diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c
> index 251ab9e..e989925 100644
> --- a/arch/arm/kvm/arm.c
> +++ b/arch/arm/kvm/arm.c
> @@ -87,11 +87,6 @@ struct kvm_vcpu * __percpu *kvm_get_running_vcpus(void)
>  	return &kvm_arm_running_vcpu;
>  }
>  
> -int kvm_arch_hardware_enable(void)
> -{
> -	return 0;
> -}
> -
>  int kvm_arch_vcpu_should_kick(struct kvm_vcpu *vcpu)
>  {
>  	return kvm_vcpu_exiting_guest_mode(vcpu) == IN_GUEST_MODE;
> @@ -885,6 +880,9 @@ static void cpu_init_hyp_mode(void *dummy)

Since you removed the IPI, why do you keep the dummy argument?

>  	unsigned long stack_page;
>  	unsigned long vector_ptr;
>  
> +	if (__hyp_get_vectors() != hyp_default_vectors)
> +		return;
> +
>  	/* Switch from the HYP stub to our own HYP init vector */
>  	__hyp_set_vectors(kvm_get_idmap_vector());
>  
> @@ -921,6 +919,10 @@ static int hyp_init_cpu_notify(struct notifier_block *self,
>  		if (__hyp_get_vectors() == hyp_default_vectors)
>  			cpu_init_hyp_mode(NULL);
>  		break;
> +	case CPU_DYING:
> +	case CPU_DYING_FROZEN:
> +		kvm_cpu_reset(NULL);
> +		break;
>  	}
>  
>  	return NOTIFY_OK;
> @@ -936,6 +938,7 @@ static int hyp_init_cpu_pm_notifier(struct notifier_block *self,
>  				    void *v)
>  {
>  	if (cmd == CPU_PM_EXIT &&
> +	    kvm_arm_get_running_vcpu() &&
>  	    __hyp_get_vectors() == hyp_default_vectors) {
>  		cpu_init_hyp_mode(NULL);
>  		return NOTIFY_OK;
> @@ -1039,11 +1042,6 @@ static int init_hyp_mode(void)
>  	}
>  
>  	/*
> -	 * Execute the init code on each CPU.
> -	 */
> -	on_each_cpu(cpu_init_hyp_mode, NULL, 1);
> -
> -	/*
>  	 * Init HYP view of VGIC
>  	 */
>  	err = kvm_vgic_hyp_init();
> @@ -1144,6 +1142,17 @@ out_err:
>  	return err;
>  }
>  
> +int kvm_arch_hardware_enable(void)
> +{
> +	cpu_init_hyp_mode(NULL);
> +	return 0;
> +}
> +
> +void kvm_arch_hardware_disable(void)
> +{
> +	kvm_cpu_reset(NULL);
> +}
> +

Bahhh... Just rename cpu_init_hyp_mode to kvm_arch_hardware_enable, and
kvM_cpu_reset to kvm_arch_hardware_disable. I don't see the point of
keeping this indirection.

>  /* NOP: Compiling as a module not supported */
>  void kvm_arch_exit(void)
>  {
> diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
> index 6a8da9c..831e6a4 100644
> --- a/arch/arm64/include/asm/kvm_host.h
> +++ b/arch/arm64/include/asm/kvm_host.h
> @@ -262,7 +262,6 @@ static inline void vgic_arch_setup(const struct vgic_params *vgic)
>  	}
>  }
>  
> -static inline void kvm_arch_hardware_disable(void) {}
>  static inline void kvm_arch_hardware_unsetup(void) {}
>  static inline void kvm_arch_sync_events(struct kvm *kvm) {}
>  static inline void kvm_arch_vcpu_uninit(struct kvm_vcpu *vcpu) {}
> 


-- 
Jazz is not dead. It just smells funny...

[v4 4/4] arm: kvm: add stub implementation for kvm_cpu_reset()

[Marc Zyngier]

On 08/05/15 02:18, AKASHI Takahiro wrote:
> Just to avoid compiling errors on arm.
> 
> Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
> ---
>  arch/arm/include/asm/kvm_asm.h  |    1 +
>  arch/arm/include/asm/kvm_host.h |   12 ++++++++++++
>  arch/arm/include/asm/kvm_mmu.h  |    5 +++++
>  arch/arm/kvm/init.S             |    6 ++++++
>  4 files changed, 24 insertions(+)
> 
> diff --git a/arch/arm/include/asm/kvm_asm.h b/arch/arm/include/asm/kvm_asm.h
> index 25410b2..462babf 100644
> --- a/arch/arm/include/asm/kvm_asm.h
> +++ b/arch/arm/include/asm/kvm_asm.h
> @@ -85,6 +85,7 @@ struct kvm_vcpu;
>  
>  extern char __kvm_hyp_init[];
>  extern char __kvm_hyp_init_end[];
> +extern char __kvm_hyp_reset[];
>  
>  extern char __kvm_hyp_exit[];
>  extern char __kvm_hyp_exit_end[];
> diff --git a/arch/arm/include/asm/kvm_host.h b/arch/arm/include/asm/kvm_host.h
> index ca97764..6d38134 100644
> --- a/arch/arm/include/asm/kvm_host.h
> +++ b/arch/arm/include/asm/kvm_host.h
> @@ -220,6 +220,18 @@ static inline void __cpu_init_hyp_mode(phys_addr_t boot_pgd_ptr,
>  	kvm_call_hyp((void*)hyp_stack_ptr, vector_ptr, pgd_ptr);
>  }
>  
> +static inline void __cpu_reset_hyp_mode(phys_addr_t boot_pgd_ptr,
> +					phys_addr_t phys_idmap_start,
> +					unsigned long stub_vector_ptr,
> +					unsigned long reset_func)
> +{
> +	/*
> +	 * TODO
> +	 * kvm_call_reset(boot_pgd_ptr, phys_idmap_start, stub_vector_ptr,
> +	 *		  reset_func);
> +	 */
> +}
> +
>  static inline int kvm_arch_dev_ioctl_check_extension(long ext)
>  {
>  	return 0;
> diff --git a/arch/arm/include/asm/kvm_mmu.h b/arch/arm/include/asm/kvm_mmu.h
> index 37ca2a4..d85bcd1 100644
> --- a/arch/arm/include/asm/kvm_mmu.h
> +++ b/arch/arm/include/asm/kvm_mmu.h
> @@ -66,6 +66,7 @@ void kvm_mmu_free_memory_caches(struct kvm_vcpu *vcpu);
>  phys_addr_t kvm_mmu_get_httbr(void);
>  phys_addr_t kvm_mmu_get_boot_httbr(void);
>  phys_addr_t kvm_get_idmap_vector(void);
> +phys_addr_t kvm_get_idmap_start(void);
>  int kvm_mmu_init(void);
>  void kvm_clear_hyp_idmap(void);
>  
> @@ -270,6 +271,10 @@ static inline void __kvm_flush_dcache_pud(pud_t pud)
>  void kvm_set_way_flush(struct kvm_vcpu *vcpu);
>  void kvm_toggle_cache(struct kvm_vcpu *vcpu, bool was_enabled);
>  
> +extern char __hyp_idmap_text_start[];
> +#define kvm_virt_to_trampoline(x)       \
> +			(TRAMPOLINE_VA + ((x) - __hyp_idmap_text_start))
> +
>  #endif	/* !__ASSEMBLY__ */
>  
>  #endif /* __ARM_KVM_MMU_H__ */
> diff --git a/arch/arm/kvm/init.S b/arch/arm/kvm/init.S
> index 3988e72..9178c9a 100644
> --- a/arch/arm/kvm/init.S
> +++ b/arch/arm/kvm/init.S
> @@ -156,4 +156,10 @@ target:	@ We're now in the trampoline code, switch page tables
>  	.globl __kvm_hyp_init_end
>  __kvm_hyp_init_end:
>  
> +	.globl __kvm_hyp_reset
> +__kvm_hyp_reset:
> +	@ TODO
> +
> +	eret
> +
>  	.popsection
> 

So before this patch, KVM is broken on ARM. This is not acceptable.
Please merge it with patch #1.

Thanks,

	M.

-- 
Jazz is not dead. It just smells funny...

[v4 1/4] arm64: kvm: add a cpu tear-down function

[AKASHI Takahiro]

Marc,

Thank you for your reviews:

On 05/26/2015 06:26 PM, Marc Zyngier wrote:
> Hi Takahiro,
>
> On 08/05/15 02:18, AKASHI Takahiro wrote:
>> Cpu must be put back into its initial state, at least, in the
>> following cases in order to shutdown the system and/or re-initialize cpus
>> later on:
>> 1) kexec/kdump
>> 2) cpu hotplug (offline)
>> 3) removing kvm as a module
>>
>> To address those issues in later patches, this patch adds a tear-down
>> function, kvm_cpu_reset(), that disables D-cache & MMU and restore a vector
>> table to the initial stub at EL2.
>>
>> Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
>> ---
>>   arch/arm/kvm/arm.c                |   15 +++++++++++++++
>>   arch/arm/kvm/mmu.c                |    5 +++++
>>   arch/arm64/include/asm/kvm_asm.h  |    1 +
>>   arch/arm64/include/asm/kvm_host.h |   11 +++++++++++
>>   arch/arm64/include/asm/kvm_mmu.h  |    7 +++++++
>>   arch/arm64/include/asm/virt.h     |   11 +++++++++++
>>   arch/arm64/kvm/hyp-init.S         |   32 ++++++++++++++++++++++++++++++++
>>   arch/arm64/kvm/hyp.S              |   16 +++++++++++++---
>>   8 files changed, 95 insertions(+), 3 deletions(-)
>>
>> diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c
>> index 07e7eb1..251ab9e 100644
>> --- a/arch/arm/kvm/arm.c
>> +++ b/arch/arm/kvm/arm.c
>> @@ -897,6 +897,21 @@ static void cpu_init_hyp_mode(void *dummy)
>>   	__cpu_init_hyp_mode(boot_pgd_ptr, pgd_ptr, hyp_stack_ptr, vector_ptr);
>>   }
>>
>> +static void kvm_cpu_reset(void *dummy)
>
> It looks like you can entirely loose the "dummy" parameter. The only
> reason some function have this is when they are used from an IPI call.

OK. I will remove all of them.

>> +{
>> +	phys_addr_t boot_pgd_ptr;
>> +	phys_addr_t phys_idmap_start;
>> +
>> +	if (__hyp_get_vectors() == hyp_default_vectors)
>> +		return;
>> +
>> +	boot_pgd_ptr = kvm_mmu_get_boot_httbr();
>> +	phys_idmap_start = kvm_get_idmap_start();
>> +	__cpu_reset_hyp_mode(boot_pgd_ptr, phys_idmap_start,
>> +			     hyp_default_vectors,
>> +			     kvm_virt_to_trampoline(__kvm_hyp_reset));
>> +}
>> +
>>   static int hyp_init_cpu_notify(struct notifier_block *self,
>>   			       unsigned long action, void *cpu)
>>   {
>> diff --git a/arch/arm/kvm/mmu.c b/arch/arm/kvm/mmu.c
>> index 3e6859b..3631a37 100644
>> --- a/arch/arm/kvm/mmu.c
>> +++ b/arch/arm/kvm/mmu.c
>> @@ -1490,6 +1490,11 @@ phys_addr_t kvm_get_idmap_vector(void)
>>   	return hyp_idmap_vector;
>>   }
>>
>> +phys_addr_t kvm_get_idmap_start(void)
>> +{
>> +	return hyp_idmap_start;
>> +}
>> +
>>   int kvm_mmu_init(void)
>>   {
>>   	int err;
>> diff --git a/arch/arm64/include/asm/kvm_asm.h b/arch/arm64/include/asm/kvm_asm.h
>> index 4f7310f..f1c16e2 100644
>> --- a/arch/arm64/include/asm/kvm_asm.h
>> +++ b/arch/arm64/include/asm/kvm_asm.h
>> @@ -118,6 +118,7 @@ struct kvm_vcpu;
>>
>>   extern char __kvm_hyp_init[];
>>   extern char __kvm_hyp_init_end[];
>> +extern char __kvm_hyp_reset[];
>>
>>   extern char __kvm_hyp_vector[];
>>
>> diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
>> index 8ac3c70..6a8da9c 100644
>> --- a/arch/arm64/include/asm/kvm_host.h
>> +++ b/arch/arm64/include/asm/kvm_host.h
>> @@ -199,6 +199,8 @@ struct kvm_vcpu *kvm_arm_get_running_vcpu(void);
>>   struct kvm_vcpu * __percpu *kvm_get_running_vcpus(void);
>>
>>   u64 kvm_call_hyp(void *hypfn, ...);
>> +void kvm_call_reset(phys_addr_t boot_pgd_ptr, phys_addr_t phys_idmap_start,
>> +		    unsigned long stub_vector_ptr, unsigned long reset_func);
>>   void force_vm_exit(const cpumask_t *mask);
>>   void kvm_mmu_wp_memory_region(struct kvm *kvm, int slot);
>>
>> @@ -223,6 +225,15 @@ static inline void __cpu_init_hyp_mode(phys_addr_t boot_pgd_ptr,
>>   		     hyp_stack_ptr, vector_ptr);
>>   }
>>
>> +static inline void __cpu_reset_hyp_mode(phys_addr_t boot_pgd_ptr,
>> +					phys_addr_t phys_idmap_start,
>> +					unsigned long stub_vector_ptr,
>> +					unsigned long reset_func)
>> +{
>> +	kvm_call_reset(boot_pgd_ptr, phys_idmap_start, stub_vector_ptr,
>> +		       reset_func);
>> +}
>> +
>>   struct vgic_sr_vectors {
>>   	void	*save_vgic;
>>   	void	*restore_vgic;
>> diff --git a/arch/arm64/include/asm/kvm_mmu.h b/arch/arm64/include/asm/kvm_mmu.h
>> index 6458b53..facfd6d 100644
>> --- a/arch/arm64/include/asm/kvm_mmu.h
>> +++ b/arch/arm64/include/asm/kvm_mmu.h
>> @@ -96,6 +96,7 @@ void kvm_mmu_free_memory_caches(struct kvm_vcpu *vcpu);
>>   phys_addr_t kvm_mmu_get_httbr(void);
>>   phys_addr_t kvm_mmu_get_boot_httbr(void);
>>   phys_addr_t kvm_get_idmap_vector(void);
>> +phys_addr_t kvm_get_idmap_start(void);
>>   int kvm_mmu_init(void);
>>   void kvm_clear_hyp_idmap(void);
>>
>> @@ -305,5 +306,11 @@ static inline void __kvm_flush_dcache_pud(pud_t pud)
>>   void kvm_set_way_flush(struct kvm_vcpu *vcpu);
>>   void kvm_toggle_cache(struct kvm_vcpu *vcpu, bool was_enabled);
>>
>> +extern char __hyp_idmap_text_start[];
>
> If you're defining it here, then it worth considering removing the
> similar declaration from mmu.c.

Yes. I will remove them from mmu.c.

>> +#define kvm_virt_to_trampoline(x)	\
>> +		(TRAMPOLINE_VA		\
>> +		+ ((unsigned long)(x)	\
>> +		  - ((unsigned long)__hyp_idmap_text_start & PAGE_MASK)))
>> +
>>   #endif /* __ASSEMBLY__ */
>>   #endif /* __ARM64_KVM_MMU_H__ */
>> diff --git a/arch/arm64/include/asm/virt.h b/arch/arm64/include/asm/virt.h
>> index 3070096..7fcd087 100644
>> --- a/arch/arm64/include/asm/virt.h
>> +++ b/arch/arm64/include/asm/virt.h
>> @@ -61,6 +61,17 @@
>>   #define BOOT_CPU_MODE_EL1	(0xe11)
>>   #define BOOT_CPU_MODE_EL2	(0xe12)
>>
>> +/*
>> + * HVC_RESET - Reset cpu in EL2 to initial state.
>> + *
>> + * @x0: entry address in trampoline code in va
>> + * @x1: identical mapping page table in pa
>> + * @x2: start address of identical mapping in pa
>> + * @x3: initial stub vector in pa
>> + */
>> +
>> +#define HVC_RESET 5
>> +
>>   #ifndef __ASSEMBLY__
>>
>>   /*
>> diff --git a/arch/arm64/kvm/hyp-init.S b/arch/arm64/kvm/hyp-init.S
>> index c319116..2614cfc 100644
>> --- a/arch/arm64/kvm/hyp-init.S
>> +++ b/arch/arm64/kvm/hyp-init.S
>> @@ -115,6 +115,38 @@ target: /* We're now in the trampoline code, switch page tables */
>>   	eret
>>   ENDPROC(__kvm_hyp_init)
>>
>> +	/*
>> +	 * x0: HYP boot pgd
>> +	 * x1: HYP phys_idmap_start
>> +	 * x2: HYP stub vectors
>> +	 */
>> +ENTRY(__kvm_hyp_reset)
>> +	/* We're in trampoline code in VA, switch back to boot page tables */
>> +	msr	ttbr0_el2, x0
>> +	isb
>> +
>> +	/* Invalidate the old TLBs */
>> +	tlbi	alle2
>> +	dsb	sy
>> +
>> +	/* Branch into PA space */
>> +	adr	x0, 1f
>> +	bfi	x1, x0, #0, #PAGE_SHIFT
>> +	br	x1
>> +
>> +	/* We're now in idmap, disable MMU */
>> +1:	mrs	x0, sctlr_el2
>> +	ldr	x1, =SCTLR_EL2_FLAGS
>> +	bic	x0, x0, x1		// Clear SCTL_M and etc
>> +	msr	sctlr_el2, x0
>> +	isb
>> +
>> +	/* Install stub vectors */
>> +	msr	vbar_el2, x2
>
> Instead of using a parameter, can't you just do
>
> 	adr	x2, __hyp_stub_vectors
> 	msr	vbar_el2, x2
>
> ? I can't imagine a case where we don't want this behaviour, and this
> would slightly simplify the calling convention.

Yeah, but it will also enforces kvm to be statically linked to the kernel.
(not module-capable) Is that OK?

>> +
>> +	eret
>> +ENDPROC(__kvm_hyp_reset)
>> +
>>   	.ltorg
>>
>>   	.popsection
>> diff --git a/arch/arm64/kvm/hyp.S b/arch/arm64/kvm/hyp.S
>> index fd085ec..7c3bdee 100644
>> --- a/arch/arm64/kvm/hyp.S
>> +++ b/arch/arm64/kvm/hyp.S
>> @@ -1136,6 +1136,11 @@ ENTRY(kvm_call_hyp)
>>   	ret
>>   ENDPROC(kvm_call_hyp)
>>
>> +ENTRY(kvm_call_reset)
>> +	hvc	#HVC_RESET
>> +	ret
>> +ENDPROC(kvm_call_reset)
>> +
>>   .macro invalid_vector	label, target
>>   	.align	2
>>   \label:
>> @@ -1179,10 +1184,14 @@ el1_sync:					// Guest trapped into EL2
>>   	cmp	x18, #HVC_GET_VECTORS
>>   	b.ne	1f
>>   	mrs	x0, vbar_el2
>> -	b	2f
>> +	b	3f
>
> How about renaming this to something like "do_eret" once and for all so
> that we stop this dance each time someone adds a new entry point?

Good point. I will take it.

>> -1:	/* Default to HVC_CALL_HYP. */
>> +	/* jump into trampoline code */
>> +1:	cmp	x18, #HVC_RESET
>> +	b.ne	2f
>> +	br	x3				// no return
>
> Same here. If we're always jumping to the trampoline code, why do we
> have to pass it as a parameter?

We need here a physical address of reset function. It seems easy to call
kvm_virt_to_trampoline() in C code. But, yes, we can also do it in asm.

Thanks,
-Takahiro AKASHI

>>
>> +2:	/* Default to HVC_CALL_HYP. */
>>   	push	lr, xzr
>>
>>   	/*
>> @@ -1196,7 +1205,8 @@ el1_sync:					// Guest trapped into EL2
>>   	blr	lr
>>
>>   	pop	lr, xzr
>> -2:	eret
>> +
>> +3:	eret
>>
>>   el1_trap:
>>   	/*
>>
>
> Thanks,
>
> 	M.
>

[v4 2/4] arm64: kvm: add kvm cpu hotplug

[AKASHI Takahiro]

On 05/26/2015 06:35 PM, Marc Zyngier wrote:
> On 08/05/15 02:18, AKASHI Takahiro wrote:
>> This patch allows cpu cores to be up and down by adding
>> kvm_arch_hardware_enable/isable(). This way, especially in kexec case,
>> cores are reset to initial states and kexec can gracefully shutdown the
>> system and reboot a new kernel from EL2.
>>
>> Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
>> ---
>>   arch/arm/include/asm/kvm_host.h   |    1 -
>>   arch/arm/kvm/arm.c                |   29 +++++++++++++++++++----------
>>   arch/arm64/include/asm/kvm_host.h |    1 -
>>   3 files changed, 19 insertions(+), 12 deletions(-)
>>
>> diff --git a/arch/arm/include/asm/kvm_host.h b/arch/arm/include/asm/kvm_host.h
>> index 41008cd..ca97764 100644
>> --- a/arch/arm/include/asm/kvm_host.h
>> +++ b/arch/arm/include/asm/kvm_host.h
>> @@ -237,7 +237,6 @@ void kvm_mmu_wp_memory_region(struct kvm *kvm, int slot);
>>
>>   struct kvm_vcpu *kvm_mpidr_to_vcpu(struct kvm *kvm, unsigned long mpidr);
>>
>> -static inline void kvm_arch_hardware_disable(void) {}
>>   static inline void kvm_arch_hardware_unsetup(void) {}
>>   static inline void kvm_arch_sync_events(struct kvm *kvm) {}
>>   static inline void kvm_arch_vcpu_uninit(struct kvm_vcpu *vcpu) {}
>> diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c
>> index 251ab9e..e989925 100644
>> --- a/arch/arm/kvm/arm.c
>> +++ b/arch/arm/kvm/arm.c
>> @@ -87,11 +87,6 @@ struct kvm_vcpu * __percpu *kvm_get_running_vcpus(void)
>>   	return &kvm_arm_running_vcpu;
>>   }
>>
>> -int kvm_arch_hardware_enable(void)
>> -{
>> -	return 0;
>> -}
>> -
>>   int kvm_arch_vcpu_should_kick(struct kvm_vcpu *vcpu)
>>   {
>>   	return kvm_vcpu_exiting_guest_mode(vcpu) == IN_GUEST_MODE;
>> @@ -885,6 +880,9 @@ static void cpu_init_hyp_mode(void *dummy)
>
> Since you removed the IPI, why do you keep the dummy argument?

Yeah, will remove it.

>>   	unsigned long stack_page;
>>   	unsigned long vector_ptr;
>>
>> +	if (__hyp_get_vectors() != hyp_default_vectors)
>> +		return;
>> +
>>   	/* Switch from the HYP stub to our own HYP init vector */
>>   	__hyp_set_vectors(kvm_get_idmap_vector());
>>
>> @@ -921,6 +919,10 @@ static int hyp_init_cpu_notify(struct notifier_block *self,
>>   		if (__hyp_get_vectors() == hyp_default_vectors)
>>   			cpu_init_hyp_mode(NULL);
>>   		break;
>> +	case CPU_DYING:
>> +	case CPU_DYING_FROZEN:
>> +		kvm_cpu_reset(NULL);
>> +		break;
>>   	}
>>
>>   	return NOTIFY_OK;
>> @@ -936,6 +938,7 @@ static int hyp_init_cpu_pm_notifier(struct notifier_block *self,
>>   				    void *v)
>>   {
>>   	if (cmd == CPU_PM_EXIT &&
>> +	    kvm_arm_get_running_vcpu() &&
>>   	    __hyp_get_vectors() == hyp_default_vectors) {
>>   		cpu_init_hyp_mode(NULL);
>>   		return NOTIFY_OK;
>> @@ -1039,11 +1042,6 @@ static int init_hyp_mode(void)
>>   	}
>>
>>   	/*
>> -	 * Execute the init code on each CPU.
>> -	 */
>> -	on_each_cpu(cpu_init_hyp_mode, NULL, 1);
>> -
>> -	/*
>>   	 * Init HYP view of VGIC
>>   	 */
>>   	err = kvm_vgic_hyp_init();
>> @@ -1144,6 +1142,17 @@ out_err:
>>   	return err;
>>   }
>>
>> +int kvm_arch_hardware_enable(void)
>> +{
>> +	cpu_init_hyp_mode(NULL);
>> +	return 0;
>> +}
>> +
>> +void kvm_arch_hardware_disable(void)
>> +{
>> +	kvm_cpu_reset(NULL);
>> +}
>> +
>
> Bahhh... Just rename cpu_init_hyp_mode to kvm_arch_hardware_enable, and
> kvM_cpu_reset to kvm_arch_hardware_disable. I don't see the point of
> keeping this indirection.

Historical reason ...
Anyway, if we don't have to add anything else here, yes, I will rename them.

-Takahiro AKASHI

>>   /* NOP: Compiling as a module not supported */
>>   void kvm_arch_exit(void)
>>   {
>> diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
>> index 6a8da9c..831e6a4 100644
>> --- a/arch/arm64/include/asm/kvm_host.h
>> +++ b/arch/arm64/include/asm/kvm_host.h
>> @@ -262,7 +262,6 @@ static inline void vgic_arch_setup(const struct vgic_params *vgic)
>>   	}
>>   }
>>
>> -static inline void kvm_arch_hardware_disable(void) {}
>>   static inline void kvm_arch_hardware_unsetup(void) {}
>>   static inline void kvm_arch_sync_events(struct kvm *kvm) {}
>>   static inline void kvm_arch_vcpu_uninit(struct kvm_vcpu *vcpu) {}
>>
>
>

[v4 4/4] arm: kvm: add stub implementation for kvm_cpu_reset()

[AKASHI Takahiro]

On 05/26/2015 06:36 PM, Marc Zyngier wrote:
> On 08/05/15 02:18, AKASHI Takahiro wrote:
>> Just to avoid compiling errors on arm.
>>
>> Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
>> ---
>>   arch/arm/include/asm/kvm_asm.h  |    1 +
>>   arch/arm/include/asm/kvm_host.h |   12 ++++++++++++
>>   arch/arm/include/asm/kvm_mmu.h  |    5 +++++
>>   arch/arm/kvm/init.S             |    6 ++++++
>>   4 files changed, 24 insertions(+)
>>
(snip)
>
> So before this patch, KVM is broken on ARM. This is not acceptable.
> Please merge it with patch #1.

OK.

-Takahiro AKASHI


> Thanks,
>
> 	M.
>

[v4 1/4] arm64: kvm: add a cpu tear-down function

[Marc Zyngier]

Hi Takahiro,

On 27/05/15 06:21, AKASHI Takahiro wrote:
> Marc,
> 
> Thank you for your reviews:
> 
> On 05/26/2015 06:26 PM, Marc Zyngier wrote:
>> Hi Takahiro,
>>
>> On 08/05/15 02:18, AKASHI Takahiro wrote:
>>> Cpu must be put back into its initial state, at least, in the
>>> following cases in order to shutdown the system and/or re-initialize cpus
>>> later on:
>>> 1) kexec/kdump
>>> 2) cpu hotplug (offline)
>>> 3) removing kvm as a module
>>>
>>> To address those issues in later patches, this patch adds a tear-down
>>> function, kvm_cpu_reset(), that disables D-cache & MMU and restore a vector
>>> table to the initial stub at EL2.
>>>
>>> Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
>>> ---
>>>   arch/arm/kvm/arm.c                |   15 +++++++++++++++
>>>   arch/arm/kvm/mmu.c                |    5 +++++
>>>   arch/arm64/include/asm/kvm_asm.h  |    1 +
>>>   arch/arm64/include/asm/kvm_host.h |   11 +++++++++++
>>>   arch/arm64/include/asm/kvm_mmu.h  |    7 +++++++
>>>   arch/arm64/include/asm/virt.h     |   11 +++++++++++
>>>   arch/arm64/kvm/hyp-init.S         |   32 ++++++++++++++++++++++++++++++++
>>>   arch/arm64/kvm/hyp.S              |   16 +++++++++++++---
>>>   8 files changed, 95 insertions(+), 3 deletions(-)
>>>

[...]

>>> diff --git a/arch/arm64/kvm/hyp-init.S b/arch/arm64/kvm/hyp-init.S
>>> index c319116..2614cfc 100644
>>> --- a/arch/arm64/kvm/hyp-init.S
>>> +++ b/arch/arm64/kvm/hyp-init.S
>>> @@ -115,6 +115,38 @@ target: /* We're now in the trampoline code, switch page tables */
>>>   	eret
>>>   ENDPROC(__kvm_hyp_init)
>>>
>>> +	/*
>>> +	 * x0: HYP boot pgd
>>> +	 * x1: HYP phys_idmap_start
>>> +	 * x2: HYP stub vectors
>>> +	 */
>>> +ENTRY(__kvm_hyp_reset)
>>> +	/* We're in trampoline code in VA, switch back to boot page tables */
>>> +	msr	ttbr0_el2, x0
>>> +	isb
>>> +
>>> +	/* Invalidate the old TLBs */
>>> +	tlbi	alle2
>>> +	dsb	sy
>>> +
>>> +	/* Branch into PA space */
>>> +	adr	x0, 1f
>>> +	bfi	x1, x0, #0, #PAGE_SHIFT
>>> +	br	x1
>>> +
>>> +	/* We're now in idmap, disable MMU */
>>> +1:	mrs	x0, sctlr_el2
>>> +	ldr	x1, =SCTLR_EL2_FLAGS
>>> +	bic	x0, x0, x1		// Clear SCTL_M and etc
>>> +	msr	sctlr_el2, x0
>>> +	isb
>>> +
>>> +	/* Install stub vectors */
>>> +	msr	vbar_el2, x2
>>
>> Instead of using a parameter, can't you just do
>>
>> 	adr	x2, __hyp_stub_vectors
>> 	msr	vbar_el2, x2
>>
>> ? I can't imagine a case where we don't want this behaviour, and this
>> would slightly simplify the calling convention.
> 
> Yeah, but it will also enforces kvm to be statically linked to the kernel.
> (not module-capable) Is that OK?

I don't think this enforces anything to be statically linked. You don't
have to refer to the symbol from C code for module linking to work. You
may have to use a combination of ADRP + ADD :lo12: to make sure you can
reach the symbol (ADR is limited to +/- 1MB).

[...]

>>> -1:	/* Default to HVC_CALL_HYP. */
>>> +	/* jump into trampoline code */
>>> +1:	cmp	x18, #HVC_RESET
>>> +	b.ne	2f
>>> +	br	x3				// no return
>>
>> Same here. If we're always jumping to the trampoline code, why do we
>> have to pass it as a parameter?
> 
> We need here a physical address of reset function. It seems easy to call
> kvm_virt_to_trampoline() in C code. But, yes, we can also do it in asm.

I think that would be a lot clearer as it will be self-contained.

Thanks,

	M.
-- 
Jazz is not dead. It just smells funny...