diff options
| author | Stefano Stabellini <stefano.stabellini@eu.citrix.com> | 2013-07-23 17:23:54 +0000 |
|---|---|---|
| committer | Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> | 2013-08-20 10:25:35 -0400 |
| commit | ee0726407feaf504dff304fb603652fb2d778b42 (patch) | |
| tree | 408473642b805ba2e56b94766f877fcb8518f24b /arch/x86 | |
| parent | 072b2064b88f709c53a83c6ec1f1cb17bf7c0abf (diff) | |
xen/m2p: use GNTTABOP_unmap_and_replace to reinstate the original mapping
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 <stefano.stabellini@eu.citrix.com>
Reviewed-by: David Vrabel <david.vrabel@citrix.com>
Acked-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
CC: alex@alex.org.uk
CC: dcrisan@flexiant.com
[v1: Konrad fixed up the conflicts]
Conflicts:
arch/x86/xen/p2m.c
Diffstat (limited to 'arch/x86')
| -rw-r--r-- | arch/x86/xen/p2m.c | 21 |
1 files changed, 15 insertions, 6 deletions
diff --git a/arch/x86/xen/p2m.c b/arch/x86/xen/p2m.c index 74672eeac881..0d4ec35895d4 100644 --- a/arch/x86/xen/p2m.c +++ b/arch/x86/xen/p2m.c @@ -161,6 +161,7 @@ #include <asm/xen/page.h> #include <asm/xen/hypercall.h> #include <asm/xen/hypervisor.h> +#include <xen/balloon.h> #include <xen/grant_table.h> #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 @@ -990,20 +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)); + 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(); } } |