Subject: [PATCH v3 30/32] arm64: KVM: enable initialization of a 32bit vcpu

From: [email-masked] (Christoffer Dall)
Date: Tue, 23 Apr 2013 16:02:29 -0700

On Mon, Apr 08, 2013 at 05:17:32PM +0100, Marc Zyngier wrote:
> Wire the init of a 32bit vcpu by allowing 32bit modes in pstate,
> and providing sensible defaults out of reset state.
> 
> This feature is of course conditioned by the presence of 32bit
> capability on the physical CPU, and is checked by the KVM_CAP_ARM_EL1_32BIT
> capability.
> 
> Signed-off-by: Marc Zyngier <[email-masked]>
> ---
>  arch/arm64/include/asm/kvm_host.h |  2 +-
>  arch/arm64/include/uapi/asm/kvm.h |  1 +
>  arch/arm64/kvm/guest.c            |  6 ++++++
>  arch/arm64/kvm/reset.c            | 25 ++++++++++++++++++++++++-
>  include/uapi/linux/kvm.h          |  1 +
>  5 files changed, 33 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
> index d44064d..c3ec107 100644
> --- a/arch/arm64/include/asm/kvm_host.h
> +++ b/arch/arm64/include/asm/kvm_host.h
> @@ -34,7 +34,7 @@
>  #include <asm/kvm_vgic.h>
>  #include <asm/kvm_arch_timer.h>
>  
> -#define KVM_VCPU_MAX_FEATURES 1
> +#define KVM_VCPU_MAX_FEATURES 2
>  
>  /* We don't currently support large pages. */
>  #define KVM_HPAGE_GFN_SHIFT(x)	0
> diff --git a/arch/arm64/include/uapi/asm/kvm.h b/arch/arm64/include/uapi/asm/kvm.h
> index 5b1110c..5031f42 100644
> --- a/arch/arm64/include/uapi/asm/kvm.h
> +++ b/arch/arm64/include/uapi/asm/kvm.h
> @@ -75,6 +75,7 @@ struct kvm_regs {
>  #define KVM_VGIC_V2_CPU_SIZE		0x2000
>  
>  #define KVM_ARM_VCPU_POWER_OFF		0 /* CPU is started in OFF state */
> +#define KVM_ARM_VCPU_EL1_32BIT		1 /* CPU running a 32bit VM */
>  
>  struct kvm_vcpu_init {
>  	__u32 target;
> diff --git a/arch/arm64/kvm/guest.c b/arch/arm64/kvm/guest.c
> index 47d3729..74ef7d5 100644
> --- a/arch/arm64/kvm/guest.c
> +++ b/arch/arm64/kvm/guest.c
> @@ -93,6 +93,12 @@ static int set_core_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
>  	if (off == KVM_REG_ARM_CORE_REG(regs.pstate)) {
>  		unsigned long mode = (*(unsigned long *)valp) & COMPAT_PSR_MODE_MASK;
>  		switch (mode) {
> +		case COMPAT_PSR_MODE_USR:
> +		case COMPAT_PSR_MODE_FIQ:
> +		case COMPAT_PSR_MODE_IRQ:
> +		case COMPAT_PSR_MODE_SVC:
> +		case COMPAT_PSR_MODE_ABT:
> +		case COMPAT_PSR_MODE_UND:
>  		case PSR_MODE_EL0t:
>  		case PSR_MODE_EL1t:
>  		case PSR_MODE_EL1h:
> diff --git a/arch/arm64/kvm/reset.c b/arch/arm64/kvm/reset.c
> index bc33e76..a282d35 100644
> --- a/arch/arm64/kvm/reset.c
> +++ b/arch/arm64/kvm/reset.c
> @@ -35,11 +35,27 @@ static struct kvm_regs default_regs_reset = {
>  	.regs.pstate = PSR_MODE_EL1h | PSR_A_BIT | PSR_I_BIT | PSR_F_BIT,
>  };
>  
> +static struct kvm_regs default_regs_reset32 = {
> +	.regs.pstate = (COMPAT_PSR_MODE_SVC | COMPAT_PSR_A_BIT |
> +			COMPAT_PSR_I_BIT | COMPAT_PSR_F_BIT),
> +};
> +
> +static bool cpu_has_32bit_el1(void)
> +{
> +	u64 pfr0;
> +
> +	pfr0 = read_cpuid(ID_AA64PFR0_EL1);
> +	return !!(pfr0 & 0x20);

again we don't need the double negation

> +}
> +
>  int kvm_arch_dev_ioctl_check_extention(long ext)
>  {
>  	int r;
>  
>  	switch (ext) {
> +	case KVM_CAP_ARM_EL1_32BIT:
> +		r = cpu_has_32bit_el1();
> +		break;
>  	default:
>  		r = 0;
>  	}
> @@ -62,7 +78,14 @@ int kvm_reset_vcpu(struct kvm_vcpu *vcpu)
>  
>  	switch (vcpu->arch.target) {
>  	default:
> -		cpu_reset = &default_regs_reset;
> +		if (test_bit(KVM_ARM_VCPU_EL1_32BIT, vcpu->arch.features)) {
> +			if (!cpu_has_32bit_el1())
> +				return -EINVAL;

I'm not sure EINVAL is appropriate here, the value specified was not
incorrect, it's that the hardware doesn't support it. ENXIO, ENODEV, and
add that in Documentation/virtual/kvm/api.txt ?

> +			cpu_reset = &default_regs_reset32;
> +			vcpu->arch.hcr_el2 &= ~HCR_RW;
> +		} else {
> +			cpu_reset = &default_regs_reset;
> +		}
>  		break;
>  	}
>  
> diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
> index 2bf42b0..ce05763 100644
> --- a/include/uapi/linux/kvm.h
> +++ b/include/uapi/linux/kvm.h
> @@ -665,6 +665,7 @@ struct kvm_ppc_smmu_info {
>  #define KVM_CAP_PPC_EPR 86
>  #define KVM_CAP_ARM_PSCI 87
>  #define KVM_CAP_ARM_SET_DEVICE_ADDR 88
> +#define KVM_CAP_ARM_EL1_32BIT 89
>  
>  #ifdef KVM_CAP_IRQ_ROUTING
>  
> -- 
> 1.8.1.4
> 
> 
> 
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