[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [RFC PATCH 09/11] x86: Migrate spec_ctrl vendor checks to x86_vendor_is()
- To: Alejandro Vallejo <alejandro.garciavallejo@xxxxxxx>, Jan Beulich <jbeulich@xxxxxxxx>
- From: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
- Date: Thu, 11 Dec 2025 15:38:56 +0000
- 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=V51oZObenhNA+VK60UT4VaWQgdqmHpRYGC1FTnHwq/o=; b=si/pzNrIs6iUHx5PD+1c5VpFoODYNjN0hs27wpIZ5mBtPW9AraEy1a9VPA6wqkzF+i4sbRH6FEmkDUloMFnQJRzcqrHyGOekfhEX/bw7TUDju/mXGB2V6siok2nCu47y307GxRQdFoIebvSXfpssHwCpEQV7fs5JxdprlTAvLe1UbwyqUxZC9Bd7yr9AMZzPBTnPA2sBBkandxY9e4Dxcp3rFUfv4u/HYP34giMeeysDnQ5ZU44TS34xhyoI0sXfRakm9QrBzhGJPLTXrHQdeIlbB2KNz0FnCvyjBZ/hAX66b0yL9wpyZcoGfzkwkkXWx1dx4CLd/RdCZ0vkhJPCgA==
- Arc-seal: i=1; a=rsa-sha256; s=arcselector10001; d=microsoft.com; cv=none; b=vqDsP2c45MAwIkSfBEwckpRx+roO6YEBPj8+4P+ec1hrEHNx28bFLHerVcuM4uDq3fw+XRfQQpEIDBVZXM/FYAfXJVWonJKPPB0a0c0P0w3eRsjNZpoZJz2ugqiP7K1x95c//4zGKFEcgTvvJmmSaBBBKRa029BnIUhFvW03qlO4aOzcFqhDYw5Qinpuk2sajf16PoGm78xoEVA+MnTJjeDmm2QQmdgCzZnPRLPt0jVUeN9IXV2L7nxAAvfs1vxhyWb49nzc0kbdKF/i/2ttscQzJkf+S6fZanLtUmnc1TXdJivcaph27J889iavTekwb1PCr+46zY0rNMpwSax5mg==
- 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>, Jason Andryuk <jason.andryuk@xxxxxxx>, Xenia Ragiadakou <xenia.ragiadakou@xxxxxxx>, Stefano Stabellini <sstabellini@xxxxxxxxxx>, xen-devel@xxxxxxxxxxxxxxxxxxxx
- Delivery-date: Thu, 11 Dec 2025 15:39:22 +0000
- List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
On 11/12/2025 10:31 am, Alejandro Vallejo wrote:
> Seeing how both you and Andrew seem onboard with dropping cross-vendor support
I found another cross-vendor dropping which you'll want to look into.
struct svm_vcpu contains three guest_sysenter_* MSRs.
In AMD CPUs, these MSRs only have 32 bits of storage, with the upper
halfs write-discard. They are switched via VMLOAD/VMSAVE.
However, in the cross-vendor case, the upper halves are needed for 64bit
kernels setting up SYSENTER support. Therefore, they're unconditionally
intercepted so we can avoid losing the upper half.
By dropping cross-vendor support, we can get rid of these fields, allow
the guest unconditional access, and simply the MSR intercept logic a little.
~Andrew
|
