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Subject: Re: [PATCH V4 12/15] x86/hyper-v: Add HvFlushGuestAddressList
 hypercall support
To:     lantianyu1986@gmail.com
Cc:     Lan Tianyu <Tianyu.Lan@microsoft.com>, kys@microsoft.com,
        haiyangz@microsoft.com, sthemmin@microsoft.com, tglx@linutronix.de,
        mingo@redhat.com, hpa@zytor.com, x86@kernel.org,
        rkrcmar@redhat.com, devel@linuxdriverproject.org,
        linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
        michael.h.kelley@microsoft.com, vkuznets@redhat.com
References: <20181013145406.4911-1-Tianyu.Lan@microsoft.com>
 <20181013145406.4911-13-Tianyu.Lan@microsoft.com>
From:   Paolo Bonzini <pbonzini@redhat.com>
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Message-ID: <1fece0bb-ca24-5f4d-2215-93e9705144fd@redhat.com>
Date:   Mon, 15 Oct 2018 12:30:08 +0200
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In-Reply-To: <20181013145406.4911-13-Tianyu.Lan@microsoft.com>
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Sender: linux-kernel-owner@vger.kernel.org
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On 13/10/2018 16:54, lantianyu1986@gmail.com wrote:
> 
> +static int fill_flush_list(union hv_gpa_page_range gpa_list[],
> +		int offset, u64 start_gfn, u64 pages)

Pass the entire struct hv_guest_mapping_flush_list to this function,
it's simpler and it hides the gpa_list argument from
range->parse_flush_list_func.

> +	if (!range->flush_list)
> +		gpa_n = fill_flush_list(flush->gpa_list, gpa_n,
> +				range->start_gfn, range->pages);
> +	else if (range->parse_flush_list_func)
> +		gpa_n = range->parse_flush_list_func(flush->gpa_list, gpa_n,
> +				range->flush_list, fill_flush_list);
> +	else

You are making the code more complicated in order to avoid making
fill_flush_list public.  Just make it public and always go through the
parse_flush_list_func case.  In fact:

- make parse_flush_list_func an argument of hyperv_flush_guest_mapping_range

- drop struct hyperv_tlb_range completely, instead just pass a void* to
hyperv_flush_guest_mapping_range and pass it back to the callback.  The
void * can point to the start_gfn/pages pair, it can be the flush_list,
or anything else.

Paolo