From patchwork Wed Dec 19 08:52:29 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alexey Kardashevskiy X-Patchwork-Id: 1015924 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=none (mailfrom) smtp.mailfrom=vger.kernel.org (client-ip=209.132.180.67; helo=vger.kernel.org; envelope-from=kvm-ppc-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dmarc=none (p=none dis=none) header.from=ozlabs.ru Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 43KTPn4Bmvz9sNB for ; Wed, 19 Dec 2018 20:00:45 +1100 (AEDT) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728575AbeLSJA1 (ORCPT ); Wed, 19 Dec 2018 04:00:27 -0500 Received: from ozlabs.ru ([107.173.13.209]:42746 "EHLO ozlabs.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728572AbeLSJA0 (ORCPT ); Wed, 19 Dec 2018 04:00:26 -0500 Received: from fstn1-p1.ozlabs.ibm.com (localhost [IPv6:::1]) by ozlabs.ru (Postfix) with ESMTP id 7FD40AE8054B; Wed, 19 Dec 2018 03:53:26 -0500 (EST) From: Alexey Kardashevskiy To: linuxppc-dev@lists.ozlabs.org Cc: Alexey Kardashevskiy , David Gibson , kvm-ppc@vger.kernel.org, Alistair Popple , Reza Arbab , Sam Bobroff , Piotr Jaroszynski , =?utf-8?q?Leonardo_Augusto_Guimar=C3=A3es_?= =?utf-8?q?Garcia?= , Jose Ricardo Ziviani , Daniel Henrique Barboza , Alex Williamson , Paul Mackerras Subject: [PATCH kernel v6 17/20] powerpc/powernv/npu: Fault user page into the hypervisor's pagetable Date: Wed, 19 Dec 2018 19:52:29 +1100 Message-Id: <20181219085232.103441-18-aik@ozlabs.ru> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20181219085232.103441-1-aik@ozlabs.ru> References: <20181219085232.103441-1-aik@ozlabs.ru> Sender: kvm-ppc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm-ppc@vger.kernel.org When a page fault happens in a GPU, the GPU signals the OS and the GPU driver calls the fault handler which populated a page table; this allows the GPU to complete an ATS request. On the bare metal get_user_pages() is enough as it adds a pte to the kernel page table but under KVM the partition scope tree does not get updated so ATS will still fail. This reads a byte from an effective address which causes HV storage interrupt and KVM updates the partition scope tree. Signed-off-by: Alexey Kardashevskiy --- arch/powerpc/platforms/powernv/npu-dma.c | 13 +++++++------ 1 file changed, 7 insertions(+), 6 deletions(-) diff --git a/arch/powerpc/platforms/powernv/npu-dma.c b/arch/powerpc/platforms/powernv/npu-dma.c index 2c405a4..ed81426 100644 --- a/arch/powerpc/platforms/powernv/npu-dma.c +++ b/arch/powerpc/platforms/powernv/npu-dma.c @@ -1133,6 +1133,8 @@ int pnv_npu2_handle_fault(struct npu_context *context, uintptr_t *ea, u64 rc = 0, result = 0; int i, is_write; struct page *page[1]; + const char __user *u; + char c; /* mmap_sem should be held so the struct_mm must be present */ struct mm_struct *mm = context->mm; @@ -1145,18 +1147,17 @@ int pnv_npu2_handle_fault(struct npu_context *context, uintptr_t *ea, is_write ? FOLL_WRITE : 0, page, NULL, NULL); - /* - * To support virtualised environments we will have to do an - * access to the page to ensure it gets faulted into the - * hypervisor. For the moment virtualisation is not supported in - * other areas so leave the access out. - */ if (rc != 1) { status[i] = rc; result = -EFAULT; continue; } + /* Make sure partition scoped tree gets a pte */ + u = page_address(page[0]); + if (__get_user(c, u)) + result = -EFAULT; + status[i] = 0; put_page(page[0]); }