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Date: Tue, 6 Sep 2011 17:19:29 +0100
From: <stefano.stabellini@...citrix.com>
To: linux-kernel@...r.kernel.org
CC: konrad.wilk@...cle.com, xen-devel@...ts.xensource.com,
stefano.stabellini@...citrix.com, Ian.Campbell@...citrix.com,
Jeremy.Fitzhardinge@...rix.com
Subject: [PATCH v2 2/2] xen: use multicalls for m2p override grant table ops
From: Stefano Stabellini <stefano.stabellini@...citrix.com>
Replace the HYPERVISOR_grant_table_op hypercalls with multicalls.
Use the kmap_op pointer directly as argument to do the mapping as it is
guaranteed to be present up until the unmapping is done.
The mapping can be done either by m2p_add_override, in case of
!PageHighMem, or in __xen_set_pte otherwise.
Before issuing any unmapping multicalls, we need to make sure that the
mapping has already being done, because we need the kmap->handle to be
set correctly.
Also we need to do the unmapping before the page is removed from the m2p
override, so we force the unmapping in m2p_remove_override even if
PageHighMem. The value of map_op->host_addr can be used to know if the
unmapping has already happened.
Signed-off-by: Stefano Stabellini <stefano.stabellini@...citrix.com>
---
arch/x86/xen/mmu.c | 49 +++++++++++++++++++++++++++++-------------
arch/x86/xen/p2m.c | 60 ++++++++++++++++++++++++++++++++-------------------
2 files changed, 72 insertions(+), 37 deletions(-)
diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c
index e80dad5..b142315 100644
--- a/arch/x86/xen/mmu.c
+++ b/arch/x86/xen/mmu.c
@@ -317,18 +317,36 @@ static int xen_unmap_granted_page(pte_t *ptep)
mfn = (ptep->pte & PTE_PFN_MASK) >> PAGE_SHIFT;
page = m2p_find_override(mfn);
if (page != NULL && (page->private & GRANT_FRAME_BIT)) {
- int ret;
- struct gnttab_unmap_grant_ref kunmap_op;
struct gnttab_map_grant_ref *kmap_op =
(struct gnttab_map_grant_ref *) page->index;
- kunmap_op.host_addr = kmap_op->host_addr;
- kunmap_op.handle = kmap_op->handle;
- kunmap_op.dev_bus_addr = 0;
- ret = HYPERVISOR_grant_table_op(
- GNTTABOP_unmap_grant_ref, &kunmap_op, 1);
- WARN(ret, "m2p_remove_override: pfn %lx mfn %lx, failed to "
- "modify kernel mappings", page_to_pfn(page), mfn);
- return ret;
+ struct multicall_space mcs =
+ xen_mc_entry(sizeof(struct gnttab_unmap_grant_ref));
+ struct gnttab_unmap_grant_ref *kunmap_op = mcs.args;
+
+ if (kmap_op->host_addr == 0)
+ return 0;
+ /*
+ * Has the grant_op mapping multicall being issued? If not,
+ * make sure it is called now.
+ */
+ if (kmap_op->handle == -1)
+ xen_mc_flush();
+ if (kmap_op->handle == -1) {
+ printk(KERN_WARNING "xen_unmap_granted_page: mfn %lx, "
+ "failed to modify kernel mappings", mfn);
+ return -1;
+ }
+
+ kunmap_op->host_addr = kmap_op->host_addr;
+ kunmap_op->handle = kmap_op->handle;
+ kunmap_op->dev_bus_addr = 0;
+
+ MULTI_grant_table_op(mcs.mc,
+ GNTTABOP_unmap_grant_ref, kunmap_op, 1);
+
+ xen_mc_issue(PARAVIRT_LAZY_MMU);
+ kmap_op->host_addr = 0;
+ return 0;
}
return 1;
}
@@ -345,7 +363,6 @@ static inline void __xen_set_pte(pte_t *ptep, pte_t pteval)
xen_unmap_granted_page(ptep);
if (!(pte_flags(pteval) & _PAGE_USER)) {
- int ret;
struct page *page;
unsigned long mfn = (pteval.pte & PTE_PFN_MASK) >> PAGE_SHIFT;
page = m2p_find_override(mfn);
@@ -354,17 +371,19 @@ static inline void __xen_set_pte(pte_t *ptep, pte_t pteval)
* hypercall to map it instead
*/
if (page != NULL && (page->private & GRANT_FRAME_BIT)) {
+ struct multicall_space mcs =
+ xen_mc_entry(sizeof(struct gnttab_unmap_grant_ref));
struct gnttab_map_grant_ref *kmap_op =
(struct gnttab_map_grant_ref *) page->index;
unsigned long old_mfn = kmap_op->dev_bus_addr;
kmap_op->host_addr =
arbitrary_virt_to_machine(ptep).maddr;
kmap_op->dev_bus_addr = 0;
- ret = HYPERVISOR_grant_table_op(
+
+ MULTI_grant_table_op(mcs.mc,
GNTTABOP_map_grant_ref, kmap_op, 1);
- WARN(ret, "xen_set_pte: pfn %lx mfn %lx, failed to "
- "modify kernel mappings",
- page_to_pfn(page), mfn);
+
+ xen_mc_issue(PARAVIRT_LAZY_MMU);
kmap_op->dev_bus_addr = old_mfn;
return;
}
diff --git a/arch/x86/xen/p2m.c b/arch/x86/xen/p2m.c
index 1c4d2b5..287fa77 100644
--- a/arch/x86/xen/p2m.c
+++ b/arch/x86/xen/p2m.c
@@ -163,6 +163,7 @@
#include <asm/xen/hypervisor.h>
#include <xen/grant_table.h>
+#include "multicalls.h"
#include "xen-ops.h"
static void __init m2p_override_init(void);
@@ -703,10 +704,12 @@ int m2p_add_override(unsigned long mfn, struct page *page,
if (kmap_op != NULL) {
if (!PageHighMem(page)) {
- int ret = HYPERVISOR_grant_table_op(
+ struct multicall_space mcs = xen_mc_entry(sizeof(*kmap_op));
+
+ MULTI_grant_table_op(mcs.mc,
GNTTABOP_map_grant_ref, kmap_op, 1);
- WARN(ret, "m2p_add_override: pfn %lx mfn %lx, "
- "failed to modify kernel mappings", pfn, mfn);
+
+ xen_mc_issue(PARAVIRT_LAZY_MMU);
}
page->private |= GRANT_FRAME_BIT;
/* let's use dev_bus_addr to record the old mfn instead */
@@ -734,15 +737,6 @@ int m2p_remove_override(struct page *page, bool clear_pte)
if (mfn == INVALID_P2M_ENTRY || !(mfn & FOREIGN_FRAME_BIT))
return -EINVAL;
- if (!PageHighMem(page)) {
- address = (unsigned long)__va(pfn << PAGE_SHIFT);
- ptep = lookup_address(address, &level);
-
- if (WARN(ptep == NULL || level != PG_LEVEL_4K,
- "m2p_remove_override: pfn %lx not mapped", pfn))
- return -EINVAL;
- }
-
spin_lock_irqsave(&m2p_override_lock, flags);
list_del(&page->lru);
spin_unlock_irqrestore(&m2p_override_lock, flags);
@@ -751,16 +745,38 @@ int m2p_remove_override(struct page *page, bool clear_pte)
struct gnttab_map_grant_ref *map_op =
(struct gnttab_map_grant_ref *) page->index;
set_phys_to_machine(pfn, map_op->dev_bus_addr);
- if (!PageHighMem(page)) {
- int ret;
- struct gnttab_unmap_grant_ref unmap_op;
- unmap_op.host_addr = map_op->host_addr;
- unmap_op.handle = map_op->handle;
- unmap_op.dev_bus_addr = 0;
- ret = HYPERVISOR_grant_table_op(
- GNTTABOP_unmap_grant_ref, &unmap_op, 1);
- WARN(ret, "m2p_remove_override: pfn %lx mfn %lx, "
- "failed to modify kernel mappings", pfn, mfn);
+ if (map_op->host_addr != 0) {
+ struct multicall_space mcs =
+ xen_mc_entry(sizeof(struct gnttab_unmap_grant_ref));
+ struct gnttab_unmap_grant_ref *unmap_op = mcs.args;
+
+ /*
+ * Has the grant_op mapping multicall being issued? If not,
+ * make sure it is called now.
+ */
+ if (map_op->handle == -1)
+ xen_mc_flush();
+ if (map_op->handle == -1) {
+ printk(KERN_WARNING "m2p_remove_override: pfn %lx mfn %lx, "
+ "failed to modify kernel mappings", pfn, mfn);
+ return -1;
+ }
+
+ unmap_op->host_addr = map_op->host_addr;
+ unmap_op->handle = map_op->handle;
+ unmap_op->dev_bus_addr = 0;
+
+ MULTI_grant_table_op(mcs.mc,
+ GNTTABOP_unmap_grant_ref, unmap_op, 1);
+
+ xen_mc_issue(PARAVIRT_LAZY_MMU);
+
+ map_op->host_addr = 0;
+ address = (unsigned long)__va(pfn << PAGE_SHIFT);
+ ptep = lookup_address(address, &level);
+ if (WARN(ptep == NULL || level != PG_LEVEL_4K,
+ "m2p_remove_override: pfn %lx not mapped", pfn))
+ return -2;
set_pte_at(&init_mm, address, ptep,
pfn_pte(pfn, PAGE_KERNEL));
__flush_tlb_single(address);
--
1.7.2.3
--
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