From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-oi0-f72.google.com (mail-oi0-f72.google.com [209.85.218.72]) by kanga.kvack.org (Postfix) with ESMTP id 6DE426B0314 for ; Tue, 6 Jun 2017 17:54:39 -0400 (EDT) Received: by mail-oi0-f72.google.com with SMTP id h4so184006563oib.5 for ; Tue, 06 Jun 2017 14:54:39 -0700 (PDT) Received: from mail.kernel.org (mail.kernel.org. [198.145.29.99]) by mx.google.com with ESMTPS id t64si11174805ota.69.2017.06.06.14.54.38 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 06 Jun 2017 14:54:38 -0700 (PDT) Received: from mail-vk0-f51.google.com (mail-vk0-f51.google.com [209.85.213.51]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id E5ADA239EF for ; Tue, 6 Jun 2017 21:54:37 +0000 (UTC) Received: by mail-vk0-f51.google.com with SMTP id p62so51969072vkp.0 for ; Tue, 06 Jun 2017 14:54:37 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: References: <1de32b6e3ff026886713adab887a9454548d8374.1496701658.git.luto@kernel.org> From: Andy Lutomirski Date: Tue, 6 Jun 2017 14:54:16 -0700 Message-ID: Subject: Re: [RFC 10/11] x86/mm: Enable CR4.PCIDE on supported systems Content-Type: text/plain; charset="UTF-8" Sender: owner-linux-mm@kvack.org List-ID: To: Boris Ostrovsky Cc: Andy Lutomirski , X86 ML , Borislav Petkov , Linus Torvalds , Andrew Morton , Mel Gorman , "linux-mm@kvack.org" , Nadav Amit , Rik van Riel , Juergen Gross On Tue, Jun 6, 2017 at 2:48 PM, Boris Ostrovsky wrote: > On 06/06/2017 05:35 PM, Andy Lutomirski wrote: >> On Tue, Jun 6, 2017 at 2:31 PM, Boris Ostrovsky >> wrote: >>>> --- a/arch/x86/xen/setup.c >>>> +++ b/arch/x86/xen/setup.c >>>> @@ -1037,6 +1037,12 @@ void __init xen_arch_setup(void) >>>> } >>>> #endif >>>> >>>> + /* >>>> + * Xen would need some work to support PCID: CR3 handling as well >>>> + * as xen_flush_tlb_others() would need updating. >>>> + */ >>>> + setup_clear_cpu_cap(X86_FEATURE_PCID); >>> >>> Capabilities for PV guests are typically set in xen_init_capabilities() now. >> Do I need this just for PV or for all Xen guests? Do the >> hardware-assisted guests still use paravirt flushes? Does the >> hypervisor either support PCID or correctly clear the PCID CPUID bit? > > > For HVM guests Xen will DTRT for CPUID so dealing with PV should be > sufficient (and xen_arch_setup() is called on PV only anyway) > > As far as flushes are concerned for now it's PV only although I believe > Juergen is thinking about doing this on HVM too. OK. I'll move the code to xen_init_capabilities() for the next version. > > -boris -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org