linux-kernel - Re: [Xen-devel] [PATCH] xen: support 52 bit physical addresses in pv guests

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: <7fa7aa6d-6458-0d86-83a4-b3b6daebfa80@citrix.com>
Date:   Thu, 21 Sep 2017 17:16:36 +0100
From:   Andrew Cooper <andrew.cooper3@...rix.com>
To:     Boris Ostrovsky <boris.ostrovsky@...cle.com>,
        Juergen Gross <jgross@...e.com>, linux-kernel@...r.kernel.org,
        xen-devel@...ts.xenproject.org
Cc:     kirill.shutemov@...ux.intel.com
Subject: Re: [Xen-devel] [PATCH] xen: support 52 bit physical addresses in pv
 guests

On 21/09/17 17:00, Boris Ostrovsky wrote:
>
>>
>>>
>>>>
>>>> Signed-off-by: Juergen Gross <jgross@...e.com>
>>>> ---
>>>>    arch/x86/include/asm/xen/page.h | 11 ++++++++++-
>>>>    arch/x86/xen/mmu_pv.c           |  4 ++--
>>>>    2 files changed, 12 insertions(+), 3 deletions(-)
>>>>
>>>> diff --git a/arch/x86/include/asm/xen/page.h
>>>> b/arch/x86/include/asm/xen/page.h
>>>> index 07b6531813c4..bcb8b193c8d1 100644
>>>> --- a/arch/x86/include/asm/xen/page.h
>>>> +++ b/arch/x86/include/asm/xen/page.h
>>>> @@ -26,6 +26,15 @@ typedef struct xpaddr {
>>>>        phys_addr_t paddr;
>>>>    } xpaddr_t;
>>>>    +#ifdef CONFIG_X86_64
>>>> +#define XEN_PHYSICAL_MASK    ((1UL << 52) - 1)
>>>
>>>
>>> SME is not supported for PV guests but for consistency (and in case sme
>>> bit somehow gets set)
>>> #define XEN_PHYSICAL_MASK    __sme_clr(((1UL << 52) - 1))
>>
>> Hmm, really? Shouldn't we rather add something like
>>
>> BUG_ON(sme_active());
>>
>> somewhere?
>
> We can do that too.

Please don't do anything to cause Linux to crash if Xen is using SME 
itself, but leaving all of the PV guest unencrypted.

~Andrew