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Date: Wed, 2 Oct 2013 17:37:20 +0300 From: Gleb Natapov <gleb@...hat.com> To: Paolo Bonzini <pbonzini@...hat.com> Cc: Alexander Graf <agraf@...e.de>, Michael Ellerman <michael@...erman.id.au>, Benjamin Herrenschmidt <benh@...nel.crashing.org>, Paul Mackerras <paulus@...ba.org>, linux-kernel@...r.kernel.org, mpm@...enic.com, herbert@...dor.hengli.com.au, linuxppc-dev@...abs.org, kvm@...r.kernel.org, kvm-ppc@...r.kernel.org, tytso@....edu Subject: Re: [PATCH 3/3] KVM: PPC: Book3S: Add support for hwrng found on some powernv systems On Wed, Oct 02, 2013 at 04:33:18PM +0200, Paolo Bonzini wrote: > Il 02/10/2013 16:08, Alexander Graf ha scritto: > > > The hwrng is accessible by host userspace via /dev/mem. > > > > A guest should live on the same permission level as a user space > > application. If you run QEMU as UID 1000 without access to /dev/mem, why > > should the guest suddenly be able to directly access a memory location > > (MMIO) it couldn't access directly through a normal user space interface. > > > > It's basically a layering violation. > > With Michael's earlier patch in this series, the hwrng is accessible by > host userspace via /dev/hwrng, no? > Access to which can be controlled by its permission. Permission of /dev/kvm may be different. If we route hypercall via userspace and configure qemu to get entropy from /dev/hwrng everything will fall nicely together (except performance). -- Gleb. -- 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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