linux-kernel - Re: [RFC PATCH 2/3] KVM: x86: use memory

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <5368AF5A.2090905@redhat.com>
Date:	Tue, 06 May 2014 11:46:02 +0200
From:	Paolo Bonzini <pbonzini@...hat.com>
To:	Bandan Das <bsd@...hat.com>, kvm@...r.kernel.org
CC:	Marcelo Tosatti <mtosatti@...hat.com>,
	Gleb Natapov <gleb@...nel.org>, linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH 2/3] KVM: x86: use memory_prepare in fetch helper
 function

Il 06/05/2014 02:40, Bandan Das ha scritto:
> +		ret = ctxt->ops->memory_prepare(ctxt, addr, toread,
> +						exception, false,
> +						NULL, &uaddr);
> +		if (ret != X86EMUL_CONTINUE)
> +			return ret;
> +
> +		if (unlikely(kvm_is_error_hva(uaddr))) {
> +			r = X86EMUL_PROPAGATE_FAULT;
> +			return r;
> +		}

What you are doing here is basically optimizing 
kvm_read_guest_virt_helper because you know that all reads will be 
single-page and you do not need the "next_segment" in kvm_read_guest.
Good catch, but you can use kvm_read_guest_page instead of going through 
ctxt->ops->memory_prepare. :)

Paolo

> +		ret = __copy_from_user(data, (void __user *)uaddr, toread);

--
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/