Re: [PATCH kvmtool v4 6/8] KVM: arm/arm64: Back out ptrauth command-line arguments

[Andre Przywara <andre.przywara@arm.com>]

On Fri, 7 Jun 2019 12:26:27 +0100
Dave Martin <Dave.Martin@arm.com> wrote:

> Will says that the command-line arguments for controlling optional
> vcpu features are superfluous: we don't attempt to support
> migration, and this isn't QEMU.
> 
> So, remove the command-line arguments and just default pointer auth
> to on if supported.
> 
> Signed-off-by: Dave Martin <Dave.Martin@arm.com>
> 
> ---
> 
> Changes since v3:
> 
>  * New patch.  This should probably be folded into the previous one.

Yes, absolutely! Those two merged become a so much simpler patch.

For the stashed version:

Reviewed-by: Andre Przywara <andre.przywara@arm.com>

Cheers,
Andre.

> ---
>  arm/aarch64/include/kvm/kvm-config-arch.h |  6 +-----
>  arm/include/arm-common/kvm-config-arch.h  |  2 --
>  arm/kvm-cpu.c                             | 19 ++++---------------
>  3 files changed, 5 insertions(+), 22 deletions(-)
> 
> diff --git a/arm/aarch64/include/kvm/kvm-config-arch.h b/arm/aarch64/include/kvm/kvm-config-arch.h
> index 0279b13..04be43d 100644
> --- a/arm/aarch64/include/kvm/kvm-config-arch.h
> +++ b/arm/aarch64/include/kvm/kvm-config-arch.h
> @@ -8,11 +8,7 @@
>  			"Create PMUv3 device"),				\
>  	OPT_U64('\0', "kaslr-seed", &(cfg)->kaslr_seed,			\
>  			"Specify random seed for Kernel Address Space "	\
> -			"Layout Randomization (KASLR)"),		\
> -	OPT_BOOLEAN('\0', "enable-ptrauth", &(cfg)->enable_ptrauth,	\
> -			"Enables pointer authentication"),		\
> -	OPT_BOOLEAN('\0', "disable-ptrauth", &(cfg)->disable_ptrauth,	\
> -			"Disables pointer authentication"),
> +			"Layout Randomization (KASLR)"),
>  
>  #include "arm-common/kvm-config-arch.h"
>  
> diff --git a/arm/include/arm-common/kvm-config-arch.h b/arm/include/arm-common/kvm-config-arch.h
> index 1b4287d..5734c46 100644
> --- a/arm/include/arm-common/kvm-config-arch.h
> +++ b/arm/include/arm-common/kvm-config-arch.h
> @@ -10,8 +10,6 @@ struct kvm_config_arch {
>  	bool		aarch32_guest;
>  	bool		has_pmuv3;
>  	u64		kaslr_seed;
> -	bool		enable_ptrauth;
> -	bool		disable_ptrauth;
>  	enum irqchip_type irqchip;
>  	u64		fw_addr;
>  };
> diff --git a/arm/kvm-cpu.c b/arm/kvm-cpu.c
> index acd1d5f..fff8494 100644
> --- a/arm/kvm-cpu.c
> +++ b/arm/kvm-cpu.c
> @@ -68,16 +68,9 @@ struct kvm_cpu *kvm_cpu__arch_init(struct kvm *kvm, unsigned long cpu_id)
>  		vcpu_init.features[0] |= (1UL << KVM_ARM_VCPU_PSCI_0_2);
>  	}
>  
> -	/* Check Pointer Authentication command line arguments. */
> -	if (kvm->cfg.arch.enable_ptrauth && kvm->cfg.arch.disable_ptrauth)
> -		die("Both enable-ptrauth and disable-ptrauth option cannot be present");
> -	/*
> -	 * Always enable Pointer Authentication if system supports
> -	 * this extension unless disable-ptrauth option is present.
> -	 */
> +	/* Enable pointer authentication if available */
>  	if (kvm__supports_extension(kvm, KVM_CAP_ARM_PTRAUTH_ADDRESS) &&
> -	    kvm__supports_extension(kvm, KVM_CAP_ARM_PTRAUTH_GENERIC) &&
> -	    !kvm->cfg.arch.disable_ptrauth)
> +	    kvm__supports_extension(kvm, KVM_CAP_ARM_PTRAUTH_GENERIC))
>  			vcpu_init.features[0] |= ARM_VCPU_PTRAUTH_FEATURE;
>  
>  	/*
> @@ -118,12 +111,8 @@ struct kvm_cpu *kvm_cpu__arch_init(struct kvm *kvm, unsigned long cpu_id)
>  			die("Unable to find matching target");
>  	}
>  
> -	if (err || target->init(vcpu)) {
> -		if (kvm->cfg.arch.enable_ptrauth)
> -			die("Unable to initialise vcpu with pointer authentication feature");
> -		else
> -			die("Unable to initialise vcpu");
> -	}
> +	if (err || target->init(vcpu))
> +		die("Unable to initialise vcpu");
>  
>  	coalesced_offset = ioctl(kvm->sys_fd, KVM_CHECK_EXTENSION,
>  				 KVM_CAP_COALESCED_MMIO);

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