From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753213Ab3HDOj7 (ORCPT ); Sun, 4 Aug 2013 10:39:59 -0400 Received: from smtp.citrix.com ([66.165.176.89]:62550 "EHLO SMTP.CITRIX.COM" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752999Ab3HDOj6 (ORCPT ); Sun, 4 Aug 2013 10:39:58 -0400 X-IronPort-AV: E=Sophos;i="4.89,812,1367971200"; d="scan'208";a="41259541" From: Stefano Stabellini To: CC: , , , , , Subject: [PATCH v4 2/2] xen/m2p: use GNTTABOP_unmap_and_replace to reinstate the original mapping Date: Sun, 4 Aug 2013 15:39:41 +0100 Message-ID: <1375627181-14948-2-git-send-email-stefano.stabellini@eu.citrix.com> X-Mailer: git-send-email 1.7.9.5 In-Reply-To: References: MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org GNTTABOP_unmap_grant_ref unmaps a grant and replaces it with a 0 mapping instead of reinstating the original mapping. Doing so separately would be racy. To unmap a grant and reinstate the original mapping atomically we use GNTTABOP_unmap_and_replace. GNTTABOP_unmap_and_replace doesn't work with GNTMAP_contains_pte, so don't use it for kmaps. GNTTABOP_unmap_and_replace zeroes the mapping passed in new_addr so we have to reinstate it, however that is a per-cpu mapping only used for balloon scratch pages, so we can be sure that it's not going to be accessed while the mapping is not valid. Signed-off-by: Stefano Stabellini Reviewed-by: David Vrabel CC: alex@alex.org.uk CC: dcrisan@flexiant.com --- arch/x86/xen/p2m.c | 22 +++++++++++++++------- drivers/xen/gntdev.c | 11 ++--------- 2 files changed, 17 insertions(+), 16 deletions(-) diff --git a/arch/x86/xen/p2m.c b/arch/x86/xen/p2m.c index 95fb2aa..0d4ec35 100644 --- a/arch/x86/xen/p2m.c +++ b/arch/x86/xen/p2m.c @@ -161,6 +161,7 @@ #include #include #include +#include #include #include "multicalls.h" @@ -967,7 +968,10 @@ int m2p_remove_override(struct page *page, if (kmap_op != NULL) { if (!PageHighMem(page)) { struct multicall_space mcs; - struct gnttab_unmap_grant_ref *unmap_op; + struct gnttab_unmap_and_replace *unmap_op; + struct page *scratch_page = get_balloon_scratch_page(); + unsigned long scratch_page_address = (unsigned long) + __va(page_to_pfn(scratch_page) << PAGE_SHIFT); /* * It might be that we queued all the m2p grant table @@ -990,21 +994,25 @@ int m2p_remove_override(struct page *page, } mcs = xen_mc_entry( - sizeof(struct gnttab_unmap_grant_ref)); + sizeof(struct gnttab_unmap_and_replace)); unmap_op = mcs.args; unmap_op->host_addr = kmap_op->host_addr; + unmap_op->new_addr = scratch_page_address; unmap_op->handle = kmap_op->handle; - unmap_op->dev_bus_addr = 0; MULTI_grant_table_op(mcs.mc, - GNTTABOP_unmap_grant_ref, unmap_op, 1); + GNTTABOP_unmap_and_replace, unmap_op, 1); xen_mc_issue(PARAVIRT_LAZY_MMU); - set_pte_at(&init_mm, address, ptep, - pfn_pte(pfn, PAGE_KERNEL)); - __flush_tlb_single(address); + mcs = __xen_mc_entry(0); + MULTI_update_va_mapping(mcs.mc, scratch_page_address, + pfn_pte(page_to_pfn(get_balloon_scratch_page()), + PAGE_KERNEL_RO), 0); + xen_mc_issue(PARAVIRT_LAZY_MMU); + kmap_op->host_addr = 0; + put_balloon_scratch_page(); } } diff --git a/drivers/xen/gntdev.c b/drivers/xen/gntdev.c index 3c8803f..51f4c95 100644 --- a/drivers/xen/gntdev.c +++ b/drivers/xen/gntdev.c @@ -270,19 +270,12 @@ static int map_grant_pages(struct grant_map *map) * with find_grant_ptes. */ for (i = 0; i < map->count; i++) { - unsigned level; unsigned long address = (unsigned long) pfn_to_kaddr(page_to_pfn(map->pages[i])); - pte_t *ptep; - u64 pte_maddr = 0; BUG_ON(PageHighMem(map->pages[i])); - ptep = lookup_address(address, &level); - pte_maddr = arbitrary_virt_to_machine(ptep).maddr; - gnttab_set_map_op(&map->kmap_ops[i], pte_maddr, - map->flags | - GNTMAP_host_map | - GNTMAP_contains_pte, + gnttab_set_map_op(&map->kmap_ops[i], address, + map->flags | GNTMAP_host_map, map->grants[i].ref, map->grants[i].domid); } -- 1.7.2.5