Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932947AbaGOS6j (ORCPT ); Tue, 15 Jul 2014 14:58:39 -0400 Received: from userp1040.oracle.com ([156.151.31.81]:28418 "EHLO userp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932734AbaGOS6f (ORCPT ); Tue, 15 Jul 2014 14:58:35 -0400 Message-ID: <53C57A68.10100@oracle.com> Date: Tue, 15 Jul 2014 15:00:56 -0400 From: Boris Ostrovsky User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.2.0 MIME-Version: 1.0 To: Andy Lutomirski CC: "H. Peter Anvin" , "linux-kernel@vger.kernel.org" , Konrad Rzeszutek Wilk Subject: Re: [RFC PATCH] x86_64,entry,xen: Do not invoke espfix64 on Xen References: <08bf951548224b92c0316c93cf0064d90e392578.1405441297.git.luto@amacapital.net> <53C562B4.3030709@oracle.com> In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Source-IP: ucsinet21.oracle.com [156.151.31.93] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 07/15/2014 01:22 PM, Andy Lutomirski wrote: > On Tue, Jul 15, 2014 at 10:19 AM, Boris Ostrovsky > wrote: >> On 07/15/2014 12:23 PM, Andy Lutomirski wrote: >>> >>> diff --git a/arch/x86/kernel/paravirt_patch_64.c >>> b/arch/x86/kernel/paravirt_patch_64.c >>> index 3f08f34..a1da673 100644 >>> --- a/arch/x86/kernel/paravirt_patch_64.c >>> +++ b/arch/x86/kernel/paravirt_patch_64.c >>> @@ -6,7 +6,6 @@ DEF_NATIVE(pv_irq_ops, irq_disable, "cli"); >>> DEF_NATIVE(pv_irq_ops, irq_enable, "sti"); >>> DEF_NATIVE(pv_irq_ops, restore_fl, "pushq %rdi; popfq"); >>> DEF_NATIVE(pv_irq_ops, save_fl, "pushfq; popq %rax"); >>> -DEF_NATIVE(pv_cpu_ops, iret, "iretq"); >>> DEF_NATIVE(pv_mmu_ops, read_cr2, "movq %cr2, %rax"); >>> DEF_NATIVE(pv_mmu_ops, read_cr3, "movq %cr3, %rax"); >>> DEF_NATIVE(pv_mmu_ops, write_cr3, "movq %rdi, %cr3"); >>> @@ -50,7 +49,6 @@ unsigned native_patch(u8 type, u16 clobbers, void *ibuf, >>> PATCH_SITE(pv_irq_ops, save_fl); >>> PATCH_SITE(pv_irq_ops, irq_enable); >>> PATCH_SITE(pv_irq_ops, irq_disable); >>> - PATCH_SITE(pv_cpu_ops, iret); >> >> >> Does this mean that we are no longer patching IRET with a jump to a >> hypercall? >> > IIUC this means that, on native, we are no longer patching > INTERRUPT_RETURN with an "iretq" instruction, so INTERRUPT_RETURN will > remain a "jmp native_iret". I'm not sure why this patch was there in > the first place. On Xen, it should still get patched with the > hypercall (although someone should verify this). Right, I missed the fact that this is native_patch. I did some light testing and it appears to work. Are you targeting this for 3.16? One way or the other we need to disable espfix64 on PV --- I discovered that one of Peter's tests crashes the hypervisor. -boris -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/