Re: [PATCH v6 14/15] KVM: ARM: Power State Coordination Interface implementation

Marc Zyngier
2013-01-17T15:55:36Z

On 16/01/13 17:59, Christoffer Dall wrote:
> From: Marc Zyngier <marc.zyngier@arm.com>
>
> Implement the PSCI specification (ARM DEN 0022A) to control
> virtual CPUs being "powered" on or off.
>
> PSCI/KVM is detected using the KVM_CAP_ARM_PSCI capability.
>
> A virtual CPU can now be initialized in a "powered off" state,
> using the KVM_ARM_VCPU_POWER_OFF feature flag.
>
> The guest can use either SMC or HVC to execute a PSCI function.
>
> Reviewed-by: Will Deacon <will.deacon@arm.com>
> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
> Signed-off-by: Christoffer Dall <c.dall@virtualopensystems.com>

A few bits went wrong when you reworked this patch. See below.

> ---
> Documentation/virtual/kvm/api.txt | 4 +
> arch/arm/include/asm/kvm_emulate.h | 5 ++
> arch/arm/include/asm/kvm_host.h | 5 +-
> arch/arm/include/asm/kvm_psci.h | 23 ++++++++
> arch/arm/include/uapi/asm/kvm.h | 16 +++++
> arch/arm/kvm/Makefile | 2 -
> arch/arm/kvm/arm.c | 28 +++++++++-
> arch/arm/kvm/psci.c | 105 ++++++++++++++++++++++++++++++++++++
> include/uapi/linux/kvm.h | 1
> 9 files changed, 184 insertions(+), 5 deletions(-)
> create mode 100644 arch/arm/include/asm/kvm_psci.h
> create mode 100644 arch/arm/kvm/psci.c
>
> diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt
> index 38066a7a..c25439a 100644
> --- a/Documentation/virtual/kvm/api.txt
> +++ b/Documentation/virtual/kvm/api.txt
> @@ -2185,6 +2185,10 @@ return ENOEXEC for that vcpu.
> Note that because some registers reflect machine topology, all vcpus
> should be created before this ioctl is invoked.
>
> +Possible features:
> + - KVM_ARM_VCPU_POWER_OFF: Starts the CPU in a power-off state.
> + Depends on KVM_CAP_ARM_PSCI.
> +
>
> 4.78 KVM_GET_REG_LIST
>
> diff --git a/arch/arm/include/asm/kvm_emulate.h b/arch/arm/include/asm/kvm_emulate.h
> index 4c1a073..ba07de9 100644
> --- a/arch/arm/include/asm/kvm_emulate.h
> +++ b/arch/arm/include/asm/kvm_emulate.h
> @@ -32,6 +32,11 @@ 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 bool vcpu_mode_is_32bit(struct kvm_vcpu *vcpu)
> +{
> + return 1;
> +}
> +
> static inline u32 *vcpu_pc(struct kvm_vcpu *vcpu)
> {
> return (u32 *)&vcpu->arch.regs.usr_regs.ARM_pc;
> diff --git a/arch/arm/include/asm/kvm_host.h b/arch/arm/include/asm/kvm_host.h
> index e65fc96..c9ba918 100644
> --- a/arch/arm/include/asm/kvm_host.h
> +++ b/arch/arm/include/asm/kvm_host.h
> @@ -30,7 +30,7 @@
> #define KVM_COALESCED_MMIO_PAGE_OFFSET 1
> #define KVM_HAVE_ONE_REG
>
> -#define KVM_VCPU_MAX_FEATURES 0
> +#define KVM_VCPU_MAX_FEATURES 1
>
> /* We don't currently support large pages. */
> #define KVM_HPAGE_GFN_SHIFT(x) 0
> @@ -100,6 +100,9 @@ struct kvm_vcpu_arch {
> int last_pcpu;
> cpumask_t require_dcache_flush;
>
> + /* Don't run the guest: see copy_current_insn() */

Now that you made this field PSCI-specific, how about rewording the comment?

> + bool pause;
> +
> /* IO related fields */
> struct kvm_decode mmio_decode;
>
> diff --git a/arch/arm/include/asm/kvm_psci.h b/arch/arm/include/asm/kvm_psci.h
> new file mode 100644
> index 0000000..9a83d98
> --- /dev/null
> +++ b/arch/arm/include/asm/kvm_psci.h
> @@ -0,0 +1,23 @@
> +/*
> + * Copyright (C) 2012 - ARM Ltd
> + * Author: Marc Zyngier <marc.zyngier@arm.com>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> + * GNU General Public License for more details.
> + *
> + * You should have received a copy of the GNU General Public License
> + * along with this program. If not, see <http://www.gnu.org/licenses/>.
> + */
> +
> +#ifndef __ARM_KVM_PSCI_H__
> +#define __ARM_KVM_PSCI_H__
> +
> +bool kvm_psci_call(struct kvm_vcpu *vcpu);
> +
> +#endif /* __ARM_KVM_PSCI_H__ */
> diff --git a/arch/arm/include/uapi/asm/kvm.h b/arch/arm/include/uapi/asm/kvm.h
> index bbb6b23..3303ff5 100644
> --- a/arch/arm/include/uapi/asm/kvm.h
> +++ b/arch/arm/include/uapi/asm/kvm.h
> @@ -65,6 +65,8 @@ struct kvm_regs {
> #define KVM_ARM_TARGET_CORTEX_A15 0
> #define KVM_ARM_NUM_TARGETS 1
>
> +#define KVM_ARM_VCPU_POWER_OFF 0 /* CPU is started in OFF state */
> +
> struct kvm_vcpu_init {
> __u32 target;
> __u32 features[7];
> @@ -145,4 +147,18 @@ struct kvm_arch_memory_slot {
> /* Highest supported SPI, from VGIC_NR_IRQS */
> #define KVM_ARM_IRQ_GIC_MAX 127
>
> +/* PSCI interface */
> +#define KVM_PSCI_FN_BASE 0x95c1ba5e
> +#define KVM_PSCI_FN(n) (KVM_PSCI_FN_BASE + (n))
> +
> +#define KVM_PSCI_FN_CPU_SUSPEND KVM_PSCI_FN(0)
> +#define KVM_PSCI_FN_CPU_OFF KVM_PSCI_FN(1)
> +#define KVM_PSCI_FN_CPU_ON KVM_PSCI_FN(2)
> +#define KVM_PSCI_FN_MIGRATE KVM_PSCI_FN(3)
> +
> +#define KVM_PSCI_RET_SUCCESS 0
> +#define KVM_PSCI_RET_NI ((unsigned long)-1)
> +#define KVM_PSCI_RET_INVAL ((unsigned long)-2)
> +#define KVM_PSCI_RET_DENIED ((unsigned long)-3)
> +
> #endif /* __ARM_KVM_H__ */
> diff --git a/arch/arm/kvm/Makefile b/arch/arm/kvm/Makefile
> index 1e45cd9..ea27987 100644
> --- a/arch/arm/kvm/Makefile
> +++ b/arch/arm/kvm/Makefile
> @@ -18,4 +18,4 @@ kvm-arm-y = $(addprefix ../../../virt/kvm/, kvm_main.o coalesced_mmio.o)
>
> obj-y += kvm-arm.o init.o interrupts.o
> obj-y += arm.o guest.o mmu.o emulate.o reset.o
> -obj-y += coproc.o coproc_a15.o mmio.o
> +obj-y += coproc.o coproc_a15.o mmio.o psci.o
> diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c
> index 3168b9d..6ff5337 100644
> --- a/arch/arm/kvm/arm.c
> +++ b/arch/arm/kvm/arm.c
> @@ -43,6 +43,7 @@
> #include <asm/kvm_mmu.h>
> #include <asm/kvm_emulate.h>
> #include <asm/kvm_coproc.h>
> +#include <asm/kvm_psci.h>
> #include <asm/opcodes.h>
>
> #ifdef REQUIRES_VIRT
> @@ -160,6 +161,7 @@ int kvm_dev_ioctl_check_extension(long ext)
> case KVM_CAP_SYNC_MMU:
> case KVM_CAP_DESTROY_MEMORY_REGION_WORKS:
> case KVM_CAP_ONE_REG:
> + case KVM_CAP_ARM_PSCI:
> r = 1;
> break;
> case KVM_CAP_COALESCED_MMIO:
> @@ -443,13 +445,17 @@ static int handle_hvc(struct kvm_vcpu *vcpu, struct kvm_run *run)
> trace_kvm_hvc(*vcpu_pc(vcpu), *vcpu_reg(vcpu, 0),
> vcpu->arch.hsr & HSR_HVC_IMM_MASK);
>
> + if (kvm_psci_call(vcpu))
> + return 1;
> +
> return 1;

No undef injection if there is no PSCI match?

> }
>
> static int handle_smc(struct kvm_vcpu *vcpu, struct kvm_run *run)
> {
> - /* We don't support SMC; don't do that. */
> - kvm_debug("smc: at %08x", *vcpu_pc(vcpu));
> + if (!kvm_psci_call(vcpu))

Looks like you got the return value backward here.

> + return 1;
> +
> kvm_inject_undefined(vcpu);
> return 1;
> }

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