Re: [PATCH v7 1/9] KVM: arm64: Factor out firmware register handling from psci.c

From: Marc Zyngier <maz@kernel.org>
To: Raghavendra Rao Ananta <rananta@google.com>
Cc: Andrew Jones <drjones@redhat.com>,
	James Morse <james.morse@arm.com>,
	Alexandru Elisei <alexandru.elisei@arm.com>,
	Suzuki K Poulose <suzuki.poulose@arm.com>,
	Paolo Bonzini <pbonzini@redhat.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will@kernel.org>, Peter Shier <pshier@google.com>,
	Ricardo Koller <ricarkol@google.com>,
	Oliver Upton <oupton@google.com>,
	Reiji Watanabe <reijiw@google.com>,
	Jing Zhang <jingzhangos@google.com>,
	linux-arm-kernel@lists.infradead.org,
	kvmarm@lists.cs.columbia.edu, linux-kernel@vger.kernel.org,
	kvm@vger.kernel.org, Gavin Shan <gshan@redhat.com>
Subject: Re: [PATCH v7 1/9] KVM: arm64: Factor out firmware register handling from psci.c
Date: Tue, 03 May 2022 11:35:19 +0100	[thread overview]
Message-ID: <87ee1a9a54.wl-maz@kernel.org> (raw)
In-Reply-To: <20220502233853.1233742-2-rananta@google.com>

On Tue, 03 May 2022 00:38:45 +0100,
Raghavendra Rao Ananta <rananta@google.com> wrote:
> 
> Common hypercall firmware register handing is currently employed
> by psci.c. Since the upcoming patches add more of these registers,
> it's better to move the generic handling to hypercall.c for a
> cleaner presentation.
> 
> While we are at it, collect all the firmware registers under
> fw_reg_ids[] to help implement kvm_arm_get_fw_num_regs() and
> kvm_arm_copy_fw_reg_indices() in a generic way. Also, define
> KVM_REG_FEATURE_LEVEL_MASK using a GENMASK instead.

Yup. See below though.

> 
> No functional change intended.
> 
> Signed-off-by: Raghavendra Rao Ananta <rananta@google.com>
> Reviewed-by: Oliver Upton <oupton@google.com>
> Reviewed-by: Gavin Shan <gshan@redhat.com>
> ---
>  arch/arm64/kvm/guest.c       |   2 +-
>  arch/arm64/kvm/hypercalls.c  | 185 +++++++++++++++++++++++++++++++++++
>  arch/arm64/kvm/psci.c        | 183 ----------------------------------
>  include/kvm/arm_hypercalls.h |   7 ++
>  include/kvm/arm_psci.h       |   7 --
>  5 files changed, 193 insertions(+), 191 deletions(-)
> 
> diff --git a/arch/arm64/kvm/guest.c b/arch/arm64/kvm/guest.c
> index 7e15b03fbdf8..0d5cca56cbda 100644
> --- a/arch/arm64/kvm/guest.c
> +++ b/arch/arm64/kvm/guest.c
> @@ -18,7 +18,7 @@
>  #include <linux/string.h>
>  #include <linux/vmalloc.h>
>  #include <linux/fs.h>
> -#include <kvm/arm_psci.h>
> +#include <kvm/arm_hypercalls.h>
>  #include <asm/cputype.h>
>  #include <linux/uaccess.h>
>  #include <asm/fpsimd.h>
> diff --git a/arch/arm64/kvm/hypercalls.c b/arch/arm64/kvm/hypercalls.c
> index 202b8c455724..fa6d9378d8e7 100644
> --- a/arch/arm64/kvm/hypercalls.c
> +++ b/arch/arm64/kvm/hypercalls.c
> @@ -158,3 +158,188 @@ int kvm_hvc_call_handler(struct kvm_vcpu *vcpu)
>  	smccc_set_retval(vcpu, val[0], val[1], val[2], val[3]);
>  	return 1;
>  }
> +
> +static const u64 kvm_arm_fw_reg_ids[] = {
> +	KVM_REG_ARM_PSCI_VERSION,
> +	KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_1,
> +	KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2,
> +	KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_3,
> +};
> +
> +int kvm_arm_get_fw_num_regs(struct kvm_vcpu *vcpu)
> +{
> +	return ARRAY_SIZE(kvm_arm_fw_reg_ids);
> +}
> +
> +int kvm_arm_copy_fw_reg_indices(struct kvm_vcpu *vcpu, u64 __user *uindices)
> +{
> +	int i;
> +
> +	for (i = 0; i < ARRAY_SIZE(kvm_arm_fw_reg_ids); i++) {
> +		if (put_user(kvm_arm_fw_reg_ids[i], uindices++))
> +			return -EFAULT;
> +	}
> +
> +	return 0;
> +}
> +
> +#define KVM_REG_FEATURE_LEVEL_WIDTH	4
> +#define KVM_REG_FEATURE_LEVEL_MASK	GENMASK(KVM_REG_FEATURE_LEVEL_WIDTH, 0)

which translates in GENMASK(4, 0), which is 5 bit wide. Not what you
want.

Thanks,

	M.

-- 
Without deviation from the norm, progress is not possible.

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