linux-kernel - Re: [PATCH v5 03/10] arm64/hyperv: Add some missing functions to arm64

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Message-ID: <c0df9fd7-6e09-4326-b4f4-2524140dc86b@linux.microsoft.com>
Date: Thu, 27 Feb 2025 10:09:59 -0800
From: Roman Kisel <romank@...ux.microsoft.com>
To: Nuno Das Neves <nunodasneves@...ux.microsoft.com>,
 linux-hyperv@...r.kernel.org, x86@...nel.org,
 linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
 linux-arch@...r.kernel.org, linux-acpi@...r.kernel.org
Cc: kys@...rosoft.com, haiyangz@...rosoft.com, wei.liu@...nel.org,
 mhklinux@...look.com, decui@...rosoft.com, catalin.marinas@....com,
 will@...nel.org, tglx@...utronix.de, mingo@...hat.com, bp@...en8.de,
 dave.hansen@...ux.intel.com, hpa@...or.com, daniel.lezcano@...aro.org,
 joro@...tes.org, robin.murphy@....com, arnd@...db.de,
 jinankjain@...ux.microsoft.com, muminulrussell@...il.com,
 skinsburskii@...ux.microsoft.com, mrathor@...ux.microsoft.com,
 ssengar@...ux.microsoft.com, apais@...ux.microsoft.com,
 Tianyu.Lan@...rosoft.com, stanislav.kinsburskiy@...il.com,
 gregkh@...uxfoundation.org, vkuznets@...hat.com, prapal@...ux.microsoft.com,
 muislam@...rosoft.com, anrayabh@...ux.microsoft.com, rafael@...nel.org,
 lenb@...nel.org, corbet@....net
Subject: Re: [PATCH v5 03/10] arm64/hyperv: Add some missing functions to
 arm64



On 2/26/2025 3:07 PM, Nuno Das Neves wrote:
> These non-nested msr and fast hypercall functions are present in x86,
> but they must be available in both architetures for the root partition
> driver code.
> 
> Signed-off-by: Nuno Das Neves <nunodasneves@...ux.microsoft.com>
> ---
>   arch/arm64/hyperv/hv_core.c       | 17 +++++++++++++++++
>   arch/arm64/include/asm/mshyperv.h | 12 ++++++++++++
>   include/asm-generic/mshyperv.h    |  2 ++
>   3 files changed, 31 insertions(+)
> 
> diff --git a/arch/arm64/hyperv/hv_core.c b/arch/arm64/hyperv/hv_core.c
> index 69004f619c57..e33a9e3c366a 100644
> --- a/arch/arm64/hyperv/hv_core.c
> +++ b/arch/arm64/hyperv/hv_core.c
> @@ -53,6 +53,23 @@ u64 hv_do_fast_hypercall8(u16 code, u64 input)
>   }
>   EXPORT_SYMBOL_GPL(hv_do_fast_hypercall8);
>   
> +/*
> + * hv_do_fast_hypercall16 -- Invoke the specified hypercall
> + * with arguments in registers instead of physical memory.
> + * Avoids the overhead of virt_to_phys for simple hypercalls.
> + */
> +u64 hv_do_fast_hypercall16(u16 code, u64 input1, u64 input2)
> +{
> +	struct arm_smccc_res	res;
> +	u64			control;
> +
> +	control = (u64)code | HV_HYPERCALL_FAST_BIT;
> +
> +	arm_smccc_1_1_hvc(HV_FUNC_ID, control, input1, input2, &res);
> +	return res.a0;
> +}
> +EXPORT_SYMBOL_GPL(hv_do_fast_hypercall16);
> +
>   /*
>    * Set a single VP register to a 64-bit value.
>    */
> diff --git a/arch/arm64/include/asm/mshyperv.h b/arch/arm64/include/asm/mshyperv.h
> index 2e2f83bafcfb..2a900ba00622 100644
> --- a/arch/arm64/include/asm/mshyperv.h
> +++ b/arch/arm64/include/asm/mshyperv.h
> @@ -40,6 +40,18 @@ static inline u64 hv_get_msr(unsigned int reg)
>   	return hv_get_vpreg(reg);
>   }
>   
> +/*
> + * Nested is not supported on arm64
> + */
> +static inline void hv_set_non_nested_msr(unsigned int reg, u64 value)
> +{
> +	hv_set_msr(reg, value);
> +}
> +static inline u64 hv_get_non_nested_msr(unsigned int reg)
> +{
> +	return hv_get_msr(reg);
> +}
> +
>   /* SMCCC hypercall parameters */
>   #define HV_SMCCC_FUNC_NUMBER	1
>   #define HV_FUNC_ID	ARM_SMCCC_CALL_VAL(			\
> diff --git a/include/asm-generic/mshyperv.h b/include/asm-generic/mshyperv.h
> index c020d5d0ec2a..258034dfd829 100644
> --- a/include/asm-generic/mshyperv.h
> +++ b/include/asm-generic/mshyperv.h
> @@ -72,6 +72,8 @@ extern void * __percpu *hyperv_pcpu_output_arg;
>   
>   extern u64 hv_do_hypercall(u64 control, void *inputaddr, void *outputaddr);
>   extern u64 hv_do_fast_hypercall8(u16 control, u64 input8);
> +extern u64 hv_do_fast_hypercall16(u16 control, u64 input1, u64 input2);
> +
>   bool hv_isolation_type_snp(void);
>   bool hv_isolation_type_tdx(void);
>   

Reviewed-by: Roman Kisel <romank@...ux.microsoft.com>

-- 
Thank you,
Roman