linux-kernel - Re: [RFC PATCH 2/8] KVM: Add KVM_MAP_MEMORY vcpu ioctl to pre-populate guest memory

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Message-ID: <20240307025252.GH368614@ls.amr.corp.intel.com>
Date: Wed, 6 Mar 2024 18:52:52 -0800
From: Isaku Yamahata <isaku.yamahata@...ux.intel.com>
To: David Matlack <dmatlack@...gle.com>
Cc: isaku.yamahata@...el.com, kvm@...r.kernel.org, isaku.yamahata@...il.com,
	linux-kernel@...r.kernel.org,
	Sean Christopherson <seanjc@...gle.com>,
	Paolo Bonzini <pbonzini@...hat.com>,
	Michael Roth <michael.roth@....com>,
	Federico Parola <federico.parola@...ito.it>,
	isaku.yamahata@...ux.intel.com
Subject: Re: [RFC PATCH 2/8] KVM: Add KVM_MAP_MEMORY vcpu ioctl to
 pre-populate guest memory

On Wed, Mar 06, 2024 at 04:49:19PM -0800,
David Matlack <dmatlack@...gle.com> wrote:

> > +			cond_resched();
> > +
> > +		r = kvm_arch_vcpu_map_memory(vcpu, mapping);
> > +		if (r)
> > +			break;
> > +
> > +		added = true;
> > +	}
> > +
> > +	srcu_read_unlock(&vcpu->kvm->srcu, idx);
> > +	vcpu_put(vcpu);
> > +
> > +	if (added && mapping->nr_pages > 0)
> > +		r = -EAGAIN;
> 
> This can overwrite the return value from kvm_arch_vcpu_map_memory().

This is to convert ERESTART into EAGAIN.  I'll drop this check
and document EINTR so that caller should be aware of partial population.
-- 
Isaku Yamahata <isaku.yamahata@...ux.intel.com>