linux-kernel - Re: [PATCH v2 07/13] KVM: add vcpu-specific functions to read/write/translate GFNs

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Date:	Fri, 05 Jun 2015 12:26:35 +0200
From:	Paolo Bonzini <pbonzini@...hat.com>
To:	Radim Krčmář <rkrcmar@...hat.com>
CC:	linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
	guangrong.xiao@...ux.intel.com, bdas@...hat.com
Subject: Re: [PATCH v2 07/13] KVM: add vcpu-specific functions to read/write/translate
 GFNs



On 29/05/2015 21:23, Radim Krčmář wrote:
>> > +int kvm_vcpu_write_guest(struct kvm_vcpu *vcpu, gpa_t gpa, const void *data,
>> > +		         unsigned long len)
>> > +{
>> > +	gfn_t gfn = gpa >> PAGE_SHIFT;
>> > +	int seg;
>> > +	int offset = offset_in_page(gpa);
>> > +	int ret;
>> > +
>> > +	while ((seg = next_segment(len, offset)) != 0) {
>> > +		ret = kvm_vcpu_write_guest_page(vcpu, gfn, data, offset, seg);
>> > +		if (ret < 0)
>> > +			return ret;
>> > +		offset = 0;
>> > +		len -= seg;
>> > +		data += seg;
>> > +		++gfn;
>> > +	}
>> > +	return 0;
>> > +}
> (There is no need to pass vcpu, and kvm, in this API.

How so?  A single kvm_vcpu_write_guest can cross multiple slots.

Paolo

>  Extracting memslots early will help to keep more code common.
> 
>  I have patches that did a superset of this for the old API, so posting
>  them after this series is finalized will be simple.)
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