From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752918AbcF1QtR (ORCPT ); Tue, 28 Jun 2016 12:49:17 -0400 Received: from mx1.redhat.com ([209.132.183.28]:57586 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752209AbcF1QsD (ORCPT ); Tue, 28 Jun 2016 12:48:03 -0400 From: Vitaly Kuznetsov To: xen-devel@lists.xenproject.org Cc: linux-kernel@vger.kernel.org, x86@kernel.org, Stefano Stabellini , Boris Ostrovsky , David Vrabel , Juergen Gross , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , Julien Grall Subject: [PATCH linux 2/8] xen: introduce xen_vcpu_id mapping Date: Tue, 28 Jun 2016 18:47:23 +0200 Message-Id: <1467132449-1030-3-git-send-email-vkuznets@redhat.com> In-Reply-To: <1467132449-1030-1-git-send-email-vkuznets@redhat.com> References: <1467132449-1030-1-git-send-email-vkuznets@redhat.com> X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.26]); Tue, 28 Jun 2016 16:47:38 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org It may happen that Xen's and Linux's ideas of vCPU id diverge. In particular, when we crash on a secondary vCPU we may want to do kdump and unlike plain kexec where we do migrate_to_reboot_cpu() we try booting on the vCPU which crashed. This doesn't work very well for PVHVM guests as we have a number of hypercalls where we pass vCPU id as a parameter. These hypercalls either fail or do something unexpected. To solve the issue introduce percpu xen_vcpu_id mapping. ARM and PV guests get direct mapping for now. Boot CPU for PVHVM guest gets its id from CPUID. With secondary CPUs it is a bit more trickier. Currently, we initialize IPI vectors before these CPUs boot so we can't use CPUID. However, we know that physical CPU id (vLAPIC id) is Xen's vCPU id * 2, we can piggyback on that. Alternatively, we could have disabled all secondary CPUs once we detect that Xen's and Linux's ideas of vCPU id diverged. Signed-off-by: Vitaly Kuznetsov --- arch/arm/xen/enlighten.c | 10 ++++++++++ arch/x86/xen/enlighten.c | 18 +++++++++++++++++- include/xen/xen-ops.h | 1 + 3 files changed, 28 insertions(+), 1 deletion(-) diff --git a/arch/arm/xen/enlighten.c b/arch/arm/xen/enlighten.c index 75cd734..ea99ca2 100644 --- a/arch/arm/xen/enlighten.c +++ b/arch/arm/xen/enlighten.c @@ -46,6 +46,10 @@ struct shared_info *HYPERVISOR_shared_info = (void *)&xen_dummy_shared_info; DEFINE_PER_CPU(struct vcpu_info *, xen_vcpu); static struct vcpu_info __percpu *xen_vcpu_info; +/* Linux <-> Xen vCPU id mapping */ +DEFINE_PER_CPU(int, xen_vcpu_id) = -1; +EXPORT_SYMBOL_GPL(xen_vcpu_id); + /* These are unused until we support booting "pre-ballooned" */ unsigned long xen_released_pages; struct xen_memory_region xen_extra_mem[XEN_EXTRA_MEM_MAX_REGIONS] __initdata; @@ -179,6 +183,9 @@ static void xen_percpu_init(void) pr_info("Xen: initializing cpu%d\n", cpu); vcpup = per_cpu_ptr(xen_vcpu_info, cpu); + /* Direct vCPU id mapping for ARM guests. */ + per_cpu(xen_vcpu_id, cpu) = cpu; + info.mfn = virt_to_gfn(vcpup); info.offset = xen_offset_in_page(vcpup); @@ -328,6 +335,9 @@ static int __init xen_guest_init(void) if (xen_vcpu_info == NULL) return -ENOMEM; + /* Direct vCPU id mapping for ARM guests. */ + per_cpu(xen_vcpu_id, 0) = 0; + if (gnttab_setup_auto_xlat_frames(grant_frames)) { free_percpu(xen_vcpu_info); return -ENOMEM; diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c index 760789a..69f4c0c 100644 --- a/arch/x86/xen/enlighten.c +++ b/arch/x86/xen/enlighten.c @@ -59,6 +59,7 @@ #include #include #include +#include #include #include #include @@ -118,6 +119,10 @@ DEFINE_PER_CPU(struct vcpu_info *, xen_vcpu); */ DEFINE_PER_CPU(struct vcpu_info, xen_vcpu_info); +/* Linux <-> Xen vCPU id mapping */ +DEFINE_PER_CPU(int, xen_vcpu_id) = -1; +EXPORT_SYMBOL_GPL(xen_vcpu_id); + enum xen_domain_type xen_domain_type = XEN_NATIVE; EXPORT_SYMBOL_GPL(xen_domain_type); @@ -1137,8 +1142,11 @@ void xen_setup_vcpu_info_placement(void) { int cpu; - for_each_possible_cpu(cpu) + for_each_possible_cpu(cpu) { + /* Set up direct vCPU id mapping for PV guests. */ + per_cpu(xen_vcpu_id, cpu) = cpu; xen_vcpu_setup(cpu); + } /* xen_vcpu_setup managed to place the vcpu_info within the * percpu area for all cpus, so make use of it. Note that for @@ -1797,6 +1805,12 @@ static void __init init_hvm_pv_info(void) xen_setup_features(); + cpuid(base + 4, &eax, &ebx, &ecx, &edx); + if (eax & XEN_HVM_CPUID_VCPU_ID_PRESENT) + this_cpu_write(xen_vcpu_id, ebx); + else + this_cpu_write(xen_vcpu_id, smp_processor_id()); + pv_info.name = "Xen HVM"; xen_domain_type = XEN_HVM_DOMAIN; @@ -1808,6 +1822,8 @@ static int xen_hvm_cpu_notify(struct notifier_block *self, unsigned long action, int cpu = (long)hcpu; switch (action) { case CPU_UP_PREPARE: + /* vLAPIC_ID == Xen's vCPU_ID * 2 for HVM guests */ + per_cpu(xen_vcpu_id, cpu) = cpu_physical_id(cpu) / 2; xen_vcpu_setup(cpu); if (xen_have_vector_callback) { if (xen_feature(XENFEAT_hvm_safe_pvclock)) diff --git a/include/xen/xen-ops.h b/include/xen/xen-ops.h index 86abe07..b02a343 100644 --- a/include/xen/xen-ops.h +++ b/include/xen/xen-ops.h @@ -8,6 +8,7 @@ #include DECLARE_PER_CPU(struct vcpu_info *, xen_vcpu); +DECLARE_PER_CPU(int, xen_vcpu_id); void xen_arch_pre_suspend(void); void xen_arch_post_suspend(int suspend_cancelled); -- 2.5.5