From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751907AbdJELj3 (ORCPT ); Thu, 5 Oct 2017 07:39:29 -0400 Received: from mx1.redhat.com ([209.132.183.28]:52924 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751525AbdJELj2 (ORCPT ); Thu, 5 Oct 2017 07:39:28 -0400 DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com 083372579A Authentication-Results: ext-mx10.extmail.prod.ext.phx2.redhat.com; dmarc=none (p=none dis=none) header.from=redhat.com Authentication-Results: ext-mx10.extmail.prod.ext.phx2.redhat.com; spf=fail smtp.mailfrom=vkuznets@redhat.com From: Vitaly Kuznetsov To: x86@kernel.org, devel@linuxdriverproject.org Cc: linux-kernel@vger.kernel.org, "K. Y. Srinivasan" , Haiyang Zhang , Stephen Hemminger , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , Jork Loeser , Dexuan Cui Subject: [PATCH] x86/hyperv: don't use percpu areas for pcpu_flush/pcpu_flush_ex structures Date: Thu, 5 Oct 2017 13:39:24 +0200 Message-Id: <20171005113924.28021-1-vkuznets@redhat.com> X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.39]); Thu, 05 Oct 2017 11:39:28 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org hv_do_hypercall() does virt_to_phys() translation and with some configs (CONFIG_SLAB) this doesn't work for percpu areas, we pass wrong memory to hypervisor and get #GP. We could use working slow_virt_to_phys() instead but doing so kills the performance. Move pcpu_flush/pcpu_flush_ex structures out of percpu areas and allocate memory on first call. The additional level of indirection gives us a small performance penalty, in future we may consider introducing hypercall functions which avoid virt_to_phys() conversion and cache physical addresses of pcpu_flush/pcpu_flush_ex structures somewhere. Reported-by: Simon Xiao Signed-off-by: Vitaly Kuznetsov --- - Please cosider this for 4.14. --- arch/x86/hyperv/mmu.c | 34 ++++++++++++++++++++++++++++------ 1 file changed, 28 insertions(+), 6 deletions(-) diff --git a/arch/x86/hyperv/mmu.c b/arch/x86/hyperv/mmu.c index 123d9b501108..b8957309bdc4 100644 --- a/arch/x86/hyperv/mmu.c +++ b/arch/x86/hyperv/mmu.c @@ -36,9 +36,9 @@ struct hv_flush_pcpu_ex { /* Each gva in gva_list encodes up to 4096 pages to flush */ #define HV_TLB_FLUSH_UNIT (4096 * PAGE_SIZE) -static struct hv_flush_pcpu __percpu *pcpu_flush; +static struct hv_flush_pcpu __percpu **pcpu_flush; -static struct hv_flush_pcpu_ex __percpu *pcpu_flush_ex; +static struct hv_flush_pcpu_ex __percpu **pcpu_flush_ex; /* * Fills in gva_list starting from offset. Returns the number of items added. @@ -102,6 +102,7 @@ static void hyperv_flush_tlb_others(const struct cpumask *cpus, const struct flush_tlb_info *info) { int cpu, vcpu, gva_n, max_gvas; + struct hv_flush_pcpu **flush_pcpu; struct hv_flush_pcpu *flush; u64 status = U64_MAX; unsigned long flags; @@ -116,7 +117,17 @@ static void hyperv_flush_tlb_others(const struct cpumask *cpus, local_irq_save(flags); - flush = this_cpu_ptr(pcpu_flush); + flush_pcpu = this_cpu_ptr(pcpu_flush); + + if (unlikely(!*flush_pcpu)) + *flush_pcpu = page_address(alloc_page(GFP_ATOMIC)); + + flush = *flush_pcpu; + + if (unlikely(!flush)) { + local_irq_restore(flags); + goto do_native; + } if (info->mm) { flush->address_space = virt_to_phys(info->mm->pgd); @@ -173,6 +184,7 @@ static void hyperv_flush_tlb_others_ex(const struct cpumask *cpus, const struct flush_tlb_info *info) { int nr_bank = 0, max_gvas, gva_n; + struct hv_flush_pcpu_ex **flush_pcpu; struct hv_flush_pcpu_ex *flush; u64 status = U64_MAX; unsigned long flags; @@ -187,7 +199,17 @@ static void hyperv_flush_tlb_others_ex(const struct cpumask *cpus, local_irq_save(flags); - flush = this_cpu_ptr(pcpu_flush_ex); + flush_pcpu = this_cpu_ptr(pcpu_flush_ex); + + if (unlikely(!*flush_pcpu)) + *flush_pcpu = page_address(alloc_page(GFP_ATOMIC)); + + flush = *flush_pcpu; + + if (unlikely(!flush)) { + local_irq_restore(flags); + goto do_native; + } if (info->mm) { flush->address_space = virt_to_phys(info->mm->pgd); @@ -266,7 +288,7 @@ void hyper_alloc_mmu(void) return; if (!(ms_hyperv.hints & HV_X64_EX_PROCESSOR_MASKS_RECOMMENDED)) - pcpu_flush = __alloc_percpu(PAGE_SIZE, PAGE_SIZE); + pcpu_flush = alloc_percpu(struct hv_flush_pcpu *); else - pcpu_flush_ex = __alloc_percpu(PAGE_SIZE, PAGE_SIZE); + pcpu_flush_ex = alloc_percpu(struct hv_flush_pcpu_ex *); } -- 2.13.6