[PATCH v2] ARM/KVM: save and restore generic timer registers
Christoffer Dall
christoffer.dall at linaro.org
Wed Jun 19 17:16:35 EDT 2013
On Tue, Jun 11, 2013 at 05:16:59PM +0200, Andre Przywara wrote:
> For migration to work we need to save (and later restore) the state of
> each core's virtual generic timer.
> Since this is per VCPU, we can use the [gs]et_one_reg ioctl and export
> the three needed registers (control, counter, compare value).
> Though they live in cp15 space, we don't use the existing list, since
> they need special accessor functions and also the arch timer is
> optional.
>
> Changes from v1:
> - move code out of coproc.c and into guest.c and arch_timer.c
> - present the registers with their native CP15 addresses, but without
> using space in the VCPU's cp15 array
> - do the user space copying in the accessor functions
>
> Signed-off-by: Andre Przywara <andre.przywara at linaro.org>
> ---
> arch/arm/include/asm/kvm_host.h | 5 ++++
> arch/arm/include/uapi/asm/kvm.h | 16 ++++++++++
> arch/arm/kvm/arch_timer.c | 65 +++++++++++++++++++++++++++++++++++++++++
> arch/arm/kvm/guest.c | 26 ++++++++++++++++-
> 4 files changed, 111 insertions(+), 1 deletion(-)
>
> diff --git a/arch/arm/include/asm/kvm_host.h b/arch/arm/include/asm/kvm_host.h
> index 57cb786..1096e33 100644
> --- a/arch/arm/include/asm/kvm_host.h
> +++ b/arch/arm/include/asm/kvm_host.h
> @@ -224,4 +224,9 @@ static inline int kvm_arch_dev_ioctl_check_extension(long ext)
> int kvm_perf_init(void);
> int kvm_perf_teardown(void);
>
> +int kvm_arm_num_timer_regs(void);
> +int kvm_arm_copy_timer_indices(struct kvm_vcpu *, u64 __user *);
> +int kvm_arm_timer_get_reg(struct kvm_vcpu *, const struct kvm_one_reg *);
> +int kvm_arm_timer_set_reg(struct kvm_vcpu *, const struct kvm_one_reg *);
> +
> #endif /* __ARM_KVM_HOST_H__ */
> diff --git a/arch/arm/include/uapi/asm/kvm.h b/arch/arm/include/uapi/asm/kvm.h
> index c1ee007..e3b0115 100644
> --- a/arch/arm/include/uapi/asm/kvm.h
> +++ b/arch/arm/include/uapi/asm/kvm.h
> @@ -118,6 +118,22 @@ struct kvm_arch_memory_slot {
> #define KVM_REG_ARM_32_CRN_MASK 0x0000000000007800
> #define KVM_REG_ARM_32_CRN_SHIFT 11
>
> +#define KVM_REG_ARM_32_CP15 (KVM_REG_ARM | KVM_REG_SIZE_U32 | \
> + (15ULL << KVM_REG_ARM_COPROC_SHIFT))
> +#define KVM_REG_ARM_64_CP15 (KVM_REG_ARM | KVM_REG_SIZE_U64 | \
> + (15ULL << KVM_REG_ARM_COPROC_SHIFT))
> +#define KVM_REG_ARM_TIMER_CTL (KVM_REG_ARM_32_CP15 | \
> + ( 3ULL << KVM_REG_ARM_CRM_SHIFT) | \
> + (14ULL << KVM_REG_ARM_32_CRN_SHIFT) | \
> + ( 0ULL << KVM_REG_ARM_OPC1_SHIFT) | \
> + ( 1ULL << KVM_REG_ARM_32_OPC2_SHIFT))
> +#define KVM_REG_ARM_TIMER_CNT (KVM_REG_ARM_64_CP15 | \
> + (14ULL << KVM_REG_ARM_CRM_SHIFT) | \
> + ( 1ULL << KVM_REG_ARM_OPC1_SHIFT))
> +#define KVM_REG_ARM_TIMER_CVAL (KVM_REG_ARM_64_CP15 | \
> + (14ULL << KVM_REG_ARM_CRM_SHIFT) | \
> + ( 3ULL << KVM_REG_ARM_OPC1_SHIFT))
> +
> /* Normal registers are mapped as coprocessor 16. */
> #define KVM_REG_ARM_CORE (0x0010 << KVM_REG_ARM_COPROC_SHIFT)
> #define KVM_REG_ARM_CORE_REG(name) (offsetof(struct kvm_regs, name) / 4)
> diff --git a/arch/arm/kvm/arch_timer.c b/arch/arm/kvm/arch_timer.c
> index c55b608..8d709eb 100644
> --- a/arch/arm/kvm/arch_timer.c
> +++ b/arch/arm/kvm/arch_timer.c
> @@ -18,6 +18,7 @@
>
> #include <linux/cpu.h>
> #include <linux/of_irq.h>
> +#include <linux/uaccess.h>
> #include <linux/kvm.h>
> #include <linux/kvm_host.h>
> #include <linux/interrupt.h>
> @@ -171,6 +172,70 @@ static void kvm_timer_init_interrupt(void *info)
> enable_percpu_irq(timer_irq.irq, 0);
> }
>
> +int kvm_arm_num_timer_regs(void)
> +{
> + return 3;
> +}
> +
> +int kvm_arm_copy_timer_indices(struct kvm_vcpu *vcpu, u64 __user *uindices)
> +{
> + if (put_user(KVM_REG_ARM_TIMER_CTL, uindices))
> + return -EFAULT;
> + uindices++;
> + if (put_user(KVM_REG_ARM_TIMER_CNT, uindices))
> + return -EFAULT;
> + uindices++;
> + if (put_user(KVM_REG_ARM_TIMER_CVAL, uindices))
> + return -EFAULT;
> +
> + return 0;
> +}
> +
> +int kvm_arm_timer_set_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
> +{
> + struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
> + void __user *uaddr = (void __user *)(long)reg->addr;
> + u64 val;
> + int ret;
> +
> + ret = copy_from_user(&val, uaddr, KVM_REG_SIZE(reg->id));
> + if (ret != 0)
> + return ret;
> +
> + switch (reg->id) {
> + case KVM_REG_ARM_TIMER_CTL:
> + timer->cntv_ctl = val;
> + break;
> + case KVM_REG_ARM_TIMER_CNT:
> + vcpu->kvm->arch.timer.cntvoff = kvm_phys_timer_read() - val;
> + break;
> + case KVM_REG_ARM_TIMER_CVAL:
> + timer->cntv_cval = val;
> + break;
> + }
> +
> + return 0;
> +}
> +
> +int kvm_arm_timer_get_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
> +{
> + struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
> + void __user *uaddr = (void __user *)(long)reg->addr;
> + u64 val;
> +
> + switch (reg->id) {
> + case KVM_REG_ARM_TIMER_CTL:
> + val = timer->cntv_ctl;
> + break;
> + case KVM_REG_ARM_TIMER_CNT:
> + val = kvm_phys_timer_read() - vcpu->kvm->arch.timer.cntvoff;
> + break;
> + case KVM_REG_ARM_TIMER_CVAL:
> + val = timer->cntv_cval;
> + break;
> + }
> + return copy_to_user(uaddr, &val, KVM_REG_SIZE(reg->id));
> +}
>
> static int kvm_timer_cpu_notify(struct notifier_block *self,
> unsigned long action, void *cpu)
> diff --git a/arch/arm/kvm/guest.c b/arch/arm/kvm/guest.c
> index 152d036..a50ffb6 100644
> --- a/arch/arm/kvm/guest.c
> +++ b/arch/arm/kvm/guest.c
> @@ -121,7 +121,8 @@ static unsigned long num_core_regs(void)
> */
> unsigned long kvm_arm_num_regs(struct kvm_vcpu *vcpu)
> {
> - return num_core_regs() + kvm_arm_num_coproc_regs(vcpu);
> + return num_core_regs() + kvm_arm_num_coproc_regs(vcpu)
> + + kvm_arm_num_timer_regs();
> }
>
> /**
> @@ -133,6 +134,7 @@ int kvm_arm_copy_reg_indices(struct kvm_vcpu *vcpu, u64 __user *uindices)
> {
> unsigned int i;
> const u64 core_reg = KVM_REG_ARM | KVM_REG_SIZE_U32 | KVM_REG_ARM_CORE;
> + int ret;
>
> for (i = 0; i < sizeof(struct kvm_regs)/sizeof(u32); i++) {
> if (put_user(core_reg | i, uindices))
> @@ -140,9 +142,25 @@ int kvm_arm_copy_reg_indices(struct kvm_vcpu *vcpu, u64 __user *uindices)
> uindices++;
> }
>
> + ret = kvm_arm_copy_timer_indices(vcpu, uindices);
> + if (ret)
> + return ret;
> + uindices += kvm_arm_num_timer_regs();
> +
> return kvm_arm_copy_coproc_indices(vcpu, uindices);
> }
>
> +static bool is_timer_reg(u64 index)
> +{
> + switch (index) {
> + case KVM_REG_ARM_TIMER_CTL:
> + case KVM_REG_ARM_TIMER_CNT:
> + case KVM_REG_ARM_TIMER_CVAL:
> + return true;
> + }
> + return false;
> +}
> +
> int kvm_arm_get_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
> {
> /* We currently use nothing arch-specific in upper 32 bits */
> @@ -153,6 +171,9 @@ int kvm_arm_get_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
> if ((reg->id & KVM_REG_ARM_COPROC_MASK) == KVM_REG_ARM_CORE)
> return get_core_reg(vcpu, reg);
>
> + if (is_timer_reg(reg->id))
> + return kvm_arm_timer_get_reg(vcpu, reg);
> +
> return kvm_arm_coproc_get_reg(vcpu, reg);
> }
>
> @@ -166,6 +187,9 @@ int kvm_arm_set_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
> if ((reg->id & KVM_REG_ARM_COPROC_MASK) == KVM_REG_ARM_CORE)
> return set_core_reg(vcpu, reg);
>
> + if (is_timer_reg(reg->id))
> + return kvm_arm_timer_set_reg(vcpu, reg);
> +
> return kvm_arm_coproc_set_reg(vcpu, reg);
> }
>
> --
This looks good to me!
Thanks,
-Christoffer
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