[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [PATCH] x86/hvm: Configuration for Linear Address Space Separation
- To: Jan Beulich <jbeulich@xxxxxxxx>
- From: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
- Date: Mon, 30 Mar 2026 09:55:42 +0100
- Arc-authentication-results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=citrix.com; dmarc=pass action=none header.from=citrix.com; dkim=pass header.d=citrix.com; arc=none
- Arc-message-signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com; s=arcselector10001; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-AntiSpam-MessageData-ChunkCount:X-MS-Exchange-AntiSpam-MessageData-0:X-MS-Exchange-AntiSpam-MessageData-1; bh=6nTwyqSj+xjYcrFYb6izSYsz2D2CD87r2ZLpDVT2Jfo=; b=wX7xKQllVTBU8Gyfb42Fn58IuTT+vS7i1FAFXJ1j6KMjIr2aoqDCigZEAxaWN4LCazjM6Km+l08hvYDRWcD1a/aCsL0jPpBvkWpEE3S8gxtsExc/S+a/fSVi2ShlJK0lRx1dZrgX1Vj7s/WVmnXgLQYegF/FOoaccIcOtGsODX9j0b1o+3zDqV7srWIFl/J0WUe6blzpmvzUgG6naTVWYLwwc7TC7NLK6qG2IubghFz1W585+vwtJJ/+WO91kjnq7LoxUJa6v5XxEGUuZWI14S4ykrCTCc+GXVTqIIY2lexiWD3B83ZoFTwwPqQ3H8TVWzJ7QZk7IDNvEjhrrClKhw==
- Arc-seal: i=1; a=rsa-sha256; s=arcselector10001; d=microsoft.com; cv=none; b=msopv0qdPJjXrBKToM/neH28ymxDscT9YZW4+q3fyzZH/ty+3rZAUM/DqjuW/4re4+jVTf/7Dq8xGWuH6/P8wA+T5ZLSB9wcB1//h73M4gPV5MpQb8ZQRvR6qKRUJjo3WuQXUB3O09DtZE4X9n7SN0GC/ScTb6DHsoWYwURYRs//6ekvcMj4AW0NhMT9qS8KrRY5YZNcBshnpkvCEJWbwOz5HtwaJgG8yHWgYXGkxruhKoTf6/spOuum+/UJzl96WTuq5LaIaxAotrS828ZzIb/ox9YZ3G/VN0SGov5POMKRe7fxGMl3F7w0nqsjOj/CxQ1MEhuOjVdBajMJa949gw==
- Authentication-results: eu.smtp.expurgate.cloud; dkim=pass header.s=selector1 header.d=citrix.com header.i="@citrix.com" header.h="From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck"
- Authentication-results: dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=citrix.com;
- Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>, Roger Pau Monné <roger.pau@xxxxxxxxxx>, Xen-devel <xen-devel@xxxxxxxxxxxxxxxxxxxx>
- Delivery-date: Mon, 30 Mar 2026 08:56:09 +0000
- List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
On 30/03/2026 8:52 am, Jan Beulich wrote:
> On 26.03.2026 14:18, Andrew Cooper wrote:
>> LASS is a feature designed in the aftermath of Meltdown, which codifies the
>> user/kernel split in address space in order to block entire classes of
>> sidechanels. Specifically, it allows the CPU to terminate any memory access
>> into the wrong half of the address space based on linear address alone and
>> without needing a pagewalk.
>>
>> It is available in CPUs starting with Intel Sapphire Rapids (2023).
>>
>> For now, allow LASS to be opted in to, but leave it off by default. Some
>> work
>> in the emulator is going to be needed to enable it by default.
>>
>> Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
> Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
Thanks, although SPR should have been SRF. I'll fix up on commit.
>
>> Abdel is going to look into the emulator side of things, which is going to be
>> easier with this patch already in place. I intend to get it fully supported
>> for 4.22.
> It indeed as "as simple as this" if you leave out the emulator part.
Yeah, quite possibly the easiest feature I've encountered. It's a shame
we need so much plumbing change in the emulator to complete it.
~Andrew
|
