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Message-ID: <20150618142455-mutt-send-email-mst@redhat.com> Date: Thu, 18 Jun 2015 15:19:06 +0200 From: "Michael S. Tsirkin" <mst@...hat.com> To: Paolo Bonzini <pbonzini@...hat.com> Cc: Igor Mammedov <imammedo@...hat.com>, linux-kernel@...r.kernel.org, kvm@...r.kernel.org, andrey@...l.ru Subject: Re: [PATCH 3/5] vhost: support upto 509 memory regions On Thu, Jun 18, 2015 at 01:50:32PM +0200, Paolo Bonzini wrote: > > > On 18/06/2015 13:41, Michael S. Tsirkin wrote: > > On Thu, Jun 18, 2015 at 01:39:12PM +0200, Igor Mammedov wrote: > >> Lets leave decision upto users instead of making them live with > >> crashing guests. > > > > Come on, let's fix it in userspace. > > It's not trivial to fix it in userspace. Since QEMU uses RCU there > isn't a single memory map to use for a linear gpa->hva map. Could you elaborate? I'm confused by this mention of RCU. You use RCU for accesses to the memory map, correct? So memory map itself is a write side operation, as such all you need to do is take some kind of lock to prevent conflicting with other memory maps, do rcu sync under this lock. > I find it absurd that we're fighting over 12K of memory. > > Paolo I wouldn't worry so much if it didn't affect kernel/userspace API. Need to be careful there. -- MST -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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