[PATCH v12 04/16] arm64: kvm: allows kvm cpu hotplug
Marc Zyngier
marc.zyngier at arm.com
Fri Nov 27 05:54:36 PST 2015
On 24/11/15 22:25, Geoff Levand wrote:
> From: AKASHI Takahiro <takahiro.akashi at linaro.org>
>
> The current kvm implementation on arm64 does cpu-specific initialization
> at system boot, and has no way to gracefully shutdown a core in terms of
> kvm. This prevents, especially, kexec from rebooting the system on a boot
> core in EL2.
>
> This patch adds a cpu tear-down function and also puts an existing cpu-init
> code into a separate function, kvm_arch_hardware_disable() and
> kvm_arch_hardware_enable() respectively.
> We don't need arm64-specific cpu hotplug hook any more.
>
> Since this patch modifies common part of code between arm and arm64, one
> stub definition, __cpu_reset_hyp_mode(), is added on arm side to avoid
> compiling errors.
>
> Signed-off-by: AKASHI Takahiro <takahiro.akashi at linaro.org>
> ---
> arch/arm/include/asm/kvm_host.h | 10 ++++-
> arch/arm/include/asm/kvm_mmu.h | 1 +
> arch/arm/kvm/arm.c | 79 ++++++++++++++++++---------------------
> arch/arm/kvm/mmu.c | 5 +++
> arch/arm64/include/asm/kvm_host.h | 16 +++++++-
> arch/arm64/include/asm/kvm_mmu.h | 1 +
> arch/arm64/include/asm/virt.h | 9 +++++
> arch/arm64/kvm/hyp-init.S | 33 ++++++++++++++++
> arch/arm64/kvm/hyp.S | 32 ++++++++++++++--
> 9 files changed, 138 insertions(+), 48 deletions(-)
>
> diff --git a/arch/arm/include/asm/kvm_host.h b/arch/arm/include/asm/kvm_host.h
> index 6692982..9242765 100644
> --- a/arch/arm/include/asm/kvm_host.h
> +++ b/arch/arm/include/asm/kvm_host.h
> @@ -214,6 +214,15 @@ 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)
> +{
> + /*
> + * TODO
> + * kvm_call_reset(boot_pgd_ptr, phys_idmap_start);
> + */
> +}
> +
> static inline int kvm_arch_dev_ioctl_check_extension(long ext)
> {
> return 0;
> @@ -226,7 +235,6 @@ 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/include/asm/kvm_mmu.h b/arch/arm/include/asm/kvm_mmu.h
> index 405aa18..dc6fadf 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);
>
> diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c
> index eab83b2..a5d9d74 100644
> --- a/arch/arm/kvm/arm.c
> +++ b/arch/arm/kvm/arm.c
> @@ -16,7 +16,6 @@
> * Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
> */
>
> -#include <linux/cpu.h>
> #include <linux/cpu_pm.h>
> #include <linux/errno.h>
> #include <linux/err.h>
> @@ -61,6 +60,8 @@ static atomic64_t kvm_vmid_gen = ATOMIC64_INIT(1);
> static u8 kvm_next_vmid;
> static DEFINE_SPINLOCK(kvm_vmid_lock);
>
> +static DEFINE_PER_CPU(unsigned char, kvm_arm_hardware_enabled);
> +
> static void kvm_arm_set_running_vcpu(struct kvm_vcpu *vcpu)
> {
> BUG_ON(preemptible());
> @@ -85,11 +86,6 @@ 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;
> @@ -959,7 +955,7 @@ long kvm_arch_vm_ioctl(struct file *filp,
> }
> }
>
> -static void cpu_init_hyp_mode(void *dummy)
> +int kvm_arch_hardware_enable(void)
> {
> phys_addr_t boot_pgd_ptr;
> phys_addr_t pgd_ptr;
> @@ -967,6 +963,9 @@ static void cpu_init_hyp_mode(void *dummy)
> unsigned long stack_page;
> unsigned long vector_ptr;
>
> + if (__hyp_get_vectors() != hyp_default_vectors)
> + return 0;
> +
> /* Switch from the HYP stub to our own HYP init vector */
> __hyp_set_vectors(kvm_get_idmap_vector());
>
> @@ -979,38 +978,50 @@ static void cpu_init_hyp_mode(void *dummy)
> __cpu_init_hyp_mode(boot_pgd_ptr, pgd_ptr, hyp_stack_ptr, vector_ptr);
>
> kvm_arm_init_debug();
> +
> + return 0;
> }
>
> -static int hyp_init_cpu_notify(struct notifier_block *self,
> - unsigned long action, void *cpu)
> +void kvm_arch_hardware_disable(void)
> {
> - switch (action) {
> - case CPU_STARTING:
> - case CPU_STARTING_FROZEN:
> - if (__hyp_get_vectors() == hyp_default_vectors)
> - cpu_init_hyp_mode(NULL);
> - break;
> - }
> + phys_addr_t boot_pgd_ptr;
> + phys_addr_t phys_idmap_start;
>
> - return NOTIFY_OK;
> -}
> + if (__hyp_get_vectors() == hyp_default_vectors)
> + return;
>
> -static struct notifier_block hyp_init_cpu_nb = {
> - .notifier_call = hyp_init_cpu_notify,
> -};
> + 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);
> +}
>
> #ifdef CONFIG_CPU_PM
> static int hyp_init_cpu_pm_notifier(struct notifier_block *self,
> unsigned long cmd,
> void *v)
> {
> - if (cmd == CPU_PM_EXIT &&
> - __hyp_get_vectors() == hyp_default_vectors) {
> - cpu_init_hyp_mode(NULL);
> + switch (cmd) {
> + case CPU_PM_ENTER:
> + if (__hyp_get_vectors() != hyp_default_vectors)
> + __this_cpu_write(kvm_arm_hardware_enabled, 1);
> + else
> + __this_cpu_write(kvm_arm_hardware_enabled, 0);
> + /*
> + * don't call kvm_arch_hardware_disable() in case of
> + * CPU_PM_ENTER because it does't actually save any state.
> + */
> +
> + return NOTIFY_OK;
> + case CPU_PM_EXIT:
> + if (__this_cpu_read(kvm_arm_hardware_enabled))
> + kvm_arch_hardware_enable();
> +
> return NOTIFY_OK;
> - }
>
> - return NOTIFY_DONE;
> + default:
> + return NOTIFY_DONE;
> + }
> }
>
> static struct notifier_block hyp_init_cpu_pm_nb = {
> @@ -1108,11 +1119,6 @@ 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();
> @@ -1186,26 +1192,15 @@ int kvm_arch_init(void *opaque)
> }
> }
>
> - cpu_notifier_register_begin();
> -
> err = init_hyp_mode();
> if (err)
> goto out_err;
>
> - err = __register_cpu_notifier(&hyp_init_cpu_nb);
> - if (err) {
> - kvm_err("Cannot register HYP init CPU notifier (%d)\n", err);
> - goto out_err;
> - }
> -
> - cpu_notifier_register_done();
> -
> hyp_cpu_pm_init();
>
> kvm_coproc_table_init();
> return 0;
> out_err:
> - cpu_notifier_register_done();
> return err;
> }
>
> diff --git a/arch/arm/kvm/mmu.c b/arch/arm/kvm/mmu.c
> index 6984342..69b4a33 100644
> --- a/arch/arm/kvm/mmu.c
> +++ b/arch/arm/kvm/mmu.c
> @@ -1644,6 +1644,11 @@ 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_host.h b/arch/arm64/include/asm/kvm_host.h
> index a35ce72..0b540f8 100644
> --- a/arch/arm64/include/asm/kvm_host.h
> +++ b/arch/arm64/include/asm/kvm_host.h
> @@ -223,6 +223,7 @@ 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);
> void force_vm_exit(const cpumask_t *mask);
> void kvm_mmu_wp_memory_region(struct kvm *kvm, int slot);
>
> @@ -247,7 +248,20 @@ static inline void __cpu_init_hyp_mode(phys_addr_t boot_pgd_ptr,
> hyp_stack_ptr, vector_ptr);
> }
>
> -static inline void kvm_arch_hardware_disable(void) {}
> +static inline void __cpu_reset_hyp_mode(phys_addr_t boot_pgd_ptr,
> + phys_addr_t phys_idmap_start)
> +{
> + /*
> + * Call reset code, and switch back to stub hyp vectors.
> + */
> + kvm_call_reset(boot_pgd_ptr, phys_idmap_start);
> +}
> +
> +struct vgic_sr_vectors {
> + void *save_vgic;
> + void *restore_vgic;
> +};
> +
Why is this structure being re-introduced? It has been removed in 48f8bd5.
> 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/arm64/include/asm/kvm_mmu.h b/arch/arm64/include/asm/kvm_mmu.h
> index 6150567..ff5a087 100644
> --- a/arch/arm64/include/asm/kvm_mmu.h
> +++ b/arch/arm64/include/asm/kvm_mmu.h
> @@ -98,6 +98,7 @@ 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);
>
> diff --git a/arch/arm64/include/asm/virt.h b/arch/arm64/include/asm/virt.h
> index 3070096..bca79f9 100644
> --- a/arch/arm64/include/asm/virt.h
> +++ b/arch/arm64/include/asm/virt.h
> @@ -58,9 +58,18 @@
>
> #define HVC_CALL_FUNC 3
>
> +/*
> + * HVC_RESET_CPU - Reset cpu in EL2 to initial state.
> + *
> + * @x0: entry address in trampoline code in va
> + * @x1: identical mapping page table in pa
> + */
> +
> #define BOOT_CPU_MODE_EL1 (0xe11)
> #define BOOT_CPU_MODE_EL2 (0xe12)
>
> +#define HVC_RESET_CPU 4
> +
Why isn't this next to the comment that document it?
> #ifndef __ASSEMBLY__
>
> /*
> diff --git a/arch/arm64/kvm/hyp-init.S b/arch/arm64/kvm/hyp-init.S
> index 2e67a48..1925163 100644
> --- a/arch/arm64/kvm/hyp-init.S
> +++ b/arch/arm64/kvm/hyp-init.S
> @@ -139,6 +139,39 @@ merged:
> eret
> ENDPROC(__kvm_hyp_init)
>
> + /*
> + * x0: HYP boot pgd
> + * x1: HYP phys_idmap_start
> + */
> +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
I find the location of that TLBI a bit weird. If you want to do
something more useful, move it to after the MMU has been disabled.
> +
> + /* 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 */
> + adrp x0, __hyp_stub_vectors
> + add x0, x0, #:lo12:__hyp_stub_vectors
> + msr vbar_el2, x0
> +
> + eret
> +ENDPROC(__kvm_hyp_reset)
> +
> .ltorg
>
> .popsection
> diff --git a/arch/arm64/kvm/hyp.S b/arch/arm64/kvm/hyp.S
> index 1bef8db..aca11d6 100644
> --- a/arch/arm64/kvm/hyp.S
> +++ b/arch/arm64/kvm/hyp.S
> @@ -939,6 +939,11 @@ ENTRY(kvm_call_hyp)
> ret
> ENDPROC(kvm_call_hyp)
>
> +ENTRY(kvm_call_reset)
> + hvc #HVC_RESET_CPU
> + ret
> +ENDPROC(kvm_call_reset)
> +
> .macro invalid_vector label, target
> .align 2
> \label:
> @@ -982,10 +987,27 @@ el1_sync: // Guest trapped into EL2
> cmp x18, #HVC_GET_VECTORS
> b.ne 1f
> mrs x0, vbar_el2
> - b 2f
> -
> -1: /* Default to HVC_CALL_HYP. */
> + b do_eret
>
> + /* jump into trampoline code */
> +1: cmp x18, #HVC_RESET_CPU
> + b.ne 2f
> + /*
> + * Entry point is:
> + * TRAMPOLINE_VA
> + * + (__kvm_hyp_reset - (__hyp_idmap_text_start & PAGE_MASK))
> + */
> + adrp x2, __kvm_hyp_reset
> + add x2, x2, #:lo12:__kvm_hyp_reset
> + adrp x3, __hyp_idmap_text_start
> + add x3, x3, #:lo12:__hyp_idmap_text_start
> + and x3, x3, PAGE_MASK
> + sub x2, x2, x3
> + ldr x3, =TRAMPOLINE_VA
Nit: You should be able to do a "mov x3, #TRAMPOLINE_VA and avoid the
load from memory.
> + add x2, x2, x3
> + br x2 // no return
> +
> +2: /* Default to HVC_CALL_HYP. */
> push lr, xzr
>
> /*
> @@ -999,7 +1021,9 @@ el1_sync: // Guest trapped into EL2
> blr lr
>
> pop lr, xzr
> -2: eret
> +
> +do_eret:
> + eret
>
> el1_trap:
> /*
>
Thanks,
M.
--
Jazz is not dead. It just smells funny...
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