linux-kernel - Re: [PATCH 1/2] x86/hyperv: Move hv_do_rep

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Date:   Sun, 18 Apr 2021 13:09:03 +0000
From:   Wei Liu <wei.liu@...nel.org>
To:     joseph.salisbury@...rosoft.com
Cc:     kys@...rosoft.com, haiyangz@...rosoft.com, sthemmin@...rosoft.com,
        wei.liu@...nel.org, tglx@...utronix.de, mingo@...hat.com,
        bp@...en8.de, hpa@...or.com, mikelley@...rosoft.com,
        x86@...nel.org, linux-hyperv@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] x86/hyperv: Move hv_do_rep_hypercall to asm-generic

On Fri, Apr 16, 2021 at 05:43:02PM -0700, Joseph Salisbury wrote:
> From: Joseph Salisbury <joseph.salisbury@...rosoft.com>
> 
> This patch makes no functional changes.  It simply moves hv_do_rep_hypercall()
> out of arch/x86/include/asm/mshyperv.h and into asm-generic/mshyperv.h
> 
> hv_do_rep_hypercall() is architecture independent, so it makes sense that it
> should be in the architecture independent mshyperv.h, not in the x86-specific
> mshyperv.h.
> 
> This is done in preperation for a follow up patch which creates a consistent
> pattern for checking Hyper-V hypercall status.
> 
> Signed-off-by: Joseph Salisbury <joseph.salisbury@...rosoft.com>
> ---
[...]
> +static inline u64 hv_do_rep_hypercall(u16 code, u16 rep_count, u16 varhead_size,
> +				      void *input, void *output)
> +{
> +	u64 control = code;
> +	u64 status;
> +	u16 rep_comp;
> +
> +	control |= (u64)varhead_size << HV_HYPERCALL_VARHEAD_OFFSET;
> +	control |= (u64)rep_count << HV_HYPERCALL_REP_COMP_OFFSET;
> +
> +	do {
> +		status = hv_do_hypercall(control, input, output);
> +		if ((status & HV_HYPERCALL_RESULT_MASK) != HV_STATUS_SUCCESS)
> +			return status;
> +
> +		/* Bits 32-43 of status have 'Reps completed' data. */
> +		rep_comp = (status & HV_HYPERCALL_REP_COMP_MASK) >>
> +			HV_HYPERCALL_REP_COMP_OFFSET;
> +
> +		control &= ~HV_HYPERCALL_REP_START_MASK;
> +		control |= (u64)rep_comp << HV_HYPERCALL_REP_START_OFFSET;
> +
> +		touch_nmi_watchdog();

This seems to be missing in Arm. Does it compile?

Wei.

> +	} while (rep_comp < rep_count);
> +
> +	return status;
> +}
>  
>  /* Generate the guest OS identifier as described in the Hyper-V TLFS */
>  static inline  __u64 generate_guest_id(__u64 d_info1, __u64 kernel_version,
> -- 
> 2.17.1
>