linux-kernel - Re: [RFC PATCH v2 01/11] KVM: arm64: Factor out firmware register handling from psci.c

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Message-ID: <20211127131628.iihianybqbeyjdbg@gator.home>
Date:   Sat, 27 Nov 2021 14:16:28 +0100
From:   Andrew Jones <drjones@...hat.com>
To:     Raghavendra Rao Ananta <rananta@...gle.com>
Cc:     Marc Zyngier <maz@...nel.org>, James Morse <james.morse@....com>,
        Alexandru Elisei <alexandru.elisei@....com>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>, Peter Shier <pshier@...gle.com>,
        Ricardo Koller <ricarkol@...gle.com>,
        Oliver Upton <oupton@...gle.com>,
        Reiji Watanabe <reijiw@...gle.com>,
        Jing Zhang <jingzhangos@...gle.com>,
        linux-arm-kernel@...ts.infradead.org, kvmarm@...ts.cs.columbia.edu,
        linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Subject: Re: [RFC PATCH v2 01/11] KVM: arm64: Factor out firmware register
 handling from psci.c

On Sat, Nov 13, 2021 at 01:22:24AM +0000, Raghavendra Rao Ananta 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.
> 
> No functional change intended.
> 
> Signed-off-by: Raghavendra Rao Ananta <rananta@...gle.com>
> ---
>  arch/arm64/kvm/guest.c       |   2 +-
>  arch/arm64/kvm/hypercalls.c  | 170 +++++++++++++++++++++++++++++++++++
>  arch/arm64/kvm/psci.c        | 166 ----------------------------------
>  include/kvm/arm_hypercalls.h |   7 ++
>  include/kvm/arm_psci.h       |   7 --
>  5 files changed, 178 insertions(+), 174 deletions(-)
> 
> diff --git a/arch/arm64/kvm/guest.c b/arch/arm64/kvm/guest.c
> index 5ce26bedf23c..625f97f7b304 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 30da78f72b3b..9e136d91b470 100644
> --- a/arch/arm64/kvm/hypercalls.c
> +++ b/arch/arm64/kvm/hypercalls.c
> @@ -146,3 +146,173 @@ 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 fw_reg_ids[] = {
> +	KVM_REG_ARM_PSCI_VERSION,
> +	KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_1,
> +	KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2,
> +};
> +
> +int kvm_arm_get_fw_num_regs(struct kvm_vcpu *vcpu)
> +{
> +	return ARRAY_SIZE(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(fw_reg_ids); i++) {
> +		if (put_user(fw_reg_ids[i], uindices))

This is missing the ++ on uindices, so it just writes the same offset
three times.

> +			return -EFAULT;
> +	}
> +
> +	return 0;
> +}

I assume the rest of the patch is just a cut+paste move of code.

Thanks,
drew