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[xen-unstable] Tools: Remove shared page from mem_event/access/paging interfaces
 

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patchbot at xen

Mar 9, 2012, 10:44 PM


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[xen-unstable] Tools: Remove shared page from mem_event/access/paging interfaces

# HG changeset patch
# User Tim Deegan <tim [at] xen>
# Date 1331224805 0
# Node ID e639e75254e9cdc95c4957c1517c145222e79f3e
# Parent a8959e0a463f0f028ffe3858d94460681b1b3659
Tools: Remove shared page from mem_event/access/paging interfaces

Don't use the superfluous shared page, return the event channel directly as
part of the domctl struct, instead.

In-tree consumers (xenpaging, xen-access) updated. This is an ABI/API change,
so please voice any concerns.

Known pending issues:
- pager could die and its ring page could be used by some other process, yet
Xen retains the mapping to it.
- use a saner interface for the paging_load buffer.

This change also affects the x86/mm bits in the hypervisor that process the
mem_event setup domctl.

Signed-off-by: Andres Lagar-Cavilla <andres [at] lagarcavilla>
Acked-by: Tim Deegan <tim [at] xen>
Acked-by: Olaf Hering <olaf [at] aepfle>
Acked-by: Ian Campbell <ian.campbell [at] citrix>
Committed-by: Tim Deegan <tim [at] xen>
---


diff -r a8959e0a463f -r e639e75254e9 tools/libxc/xc_mem_access.c
--- a/tools/libxc/xc_mem_access.c Thu Mar 08 17:05:23 2012 +0100
+++ b/tools/libxc/xc_mem_access.c Thu Mar 08 16:40:05 2012 +0000
@@ -25,12 +25,18 @@


int xc_mem_access_enable(xc_interface *xch, domid_t domain_id,
- void *shared_page, void *ring_page)
+ uint32_t *port, void *ring_page)
{
+ if ( !port )
+ {
+ errno = EINVAL;
+ return -1;
+ }
+
return xc_mem_event_control(xch, domain_id,
XEN_DOMCTL_MEM_EVENT_OP_ACCESS_ENABLE,
XEN_DOMCTL_MEM_EVENT_OP_ACCESS,
- shared_page, ring_page);
+ port, ring_page);
}

int xc_mem_access_disable(xc_interface *xch, domid_t domain_id)
diff -r a8959e0a463f -r e639e75254e9 tools/libxc/xc_mem_event.c
--- a/tools/libxc/xc_mem_event.c Thu Mar 08 17:05:23 2012 +0100
+++ b/tools/libxc/xc_mem_event.c Thu Mar 08 16:40:05 2012 +0000
@@ -24,19 +24,21 @@
#include "xc_private.h"

int xc_mem_event_control(xc_interface *xch, domid_t domain_id, unsigned int op,
- unsigned int mode, void *page, void *ring_page)
+ unsigned int mode, uint32_t *port, void *ring_page)
{
DECLARE_DOMCTL;
+ int rc;

domctl.cmd = XEN_DOMCTL_mem_event_op;
domctl.domain = domain_id;
domctl.u.mem_event_op.op = op;
domctl.u.mem_event_op.mode = mode;
-
- domctl.u.mem_event_op.shared_addr = (unsigned long)page;
- domctl.u.mem_event_op.ring_addr = (unsigned long)ring_page;
+ domctl.u.mem_event_op.ring_addr = (unsigned long) ring_page;

- return do_domctl(xch, &domctl);
+ rc = do_domctl(xch, &domctl);
+ if ( !rc && port )
+ *port = domctl.u.mem_event_op.port;
+ return rc;
}

int xc_mem_event_memop(xc_interface *xch, domid_t domain_id,
diff -r a8959e0a463f -r e639e75254e9 tools/libxc/xc_mem_paging.c
--- a/tools/libxc/xc_mem_paging.c Thu Mar 08 17:05:23 2012 +0100
+++ b/tools/libxc/xc_mem_paging.c Thu Mar 08 16:40:05 2012 +0000
@@ -25,12 +25,18 @@


int xc_mem_paging_enable(xc_interface *xch, domid_t domain_id,
- void *shared_page, void *ring_page)
+ uint32_t *port, void *ring_page)
{
+ if ( !port )
+ {
+ errno = EINVAL;
+ return -1;
+ }
+
return xc_mem_event_control(xch, domain_id,
XEN_DOMCTL_MEM_EVENT_OP_PAGING_ENABLE,
XEN_DOMCTL_MEM_EVENT_OP_PAGING,
- shared_page, ring_page);
+ port, ring_page);
}

int xc_mem_paging_disable(xc_interface *xch, domid_t domain_id)
diff -r a8959e0a463f -r e639e75254e9 tools/libxc/xenctrl.h
--- a/tools/libxc/xenctrl.h Thu Mar 08 17:05:23 2012 +0100
+++ b/tools/libxc/xenctrl.h Thu Mar 08 16:40:05 2012 +0000
@@ -1892,13 +1892,13 @@
* mem_event operations
*/
int xc_mem_event_control(xc_interface *xch, domid_t domain_id, unsigned int op,
- unsigned int mode, void *shared_page, void *ring_page);
+ unsigned int mode, uint32_t *port, void *ring_page);
int xc_mem_event_memop(xc_interface *xch, domid_t domain_id,
unsigned int op, unsigned int mode,
uint64_t gfn, void *buffer);

int xc_mem_paging_enable(xc_interface *xch, domid_t domain_id,
- void *shared_page, void *ring_page);
+ uint32_t *port, void *ring_page);
int xc_mem_paging_disable(xc_interface *xch, domid_t domain_id);
int xc_mem_paging_nominate(xc_interface *xch, domid_t domain_id,
unsigned long gfn);
@@ -1908,7 +1908,7 @@
unsigned long gfn, void *buffer);

int xc_mem_access_enable(xc_interface *xch, domid_t domain_id,
- void *shared_page, void *ring_page);
+ uint32_t *port, void *ring_page);
int xc_mem_access_disable(xc_interface *xch, domid_t domain_id);
int xc_mem_access_resume(xc_interface *xch, domid_t domain_id,
unsigned long gfn);
diff -r a8959e0a463f -r e639e75254e9 tools/tests/xen-access/xen-access.c
--- a/tools/tests/xen-access/xen-access.c Thu Mar 08 17:05:23 2012 +0100
+++ b/tools/tests/xen-access/xen-access.c Thu Mar 08 16:40:05 2012 +0000
@@ -98,7 +98,7 @@
xc_evtchn *xce_handle;
int port;
mem_event_back_ring_t back_ring;
- mem_event_shared_page_t *shared_page;
+ uint32_t evtchn_port;
void *ring_page;
spinlock_t ring_lock;
} mem_event_t;
@@ -166,7 +166,7 @@
err:
return -errno;
}
-
+
static void *init_page(void)
{
void *buffer;
@@ -214,14 +214,6 @@
/* Set domain id */
xenaccess->mem_event.domain_id = domain_id;

- /* Initialise shared page */
- xenaccess->mem_event.shared_page = init_page();
- if ( xenaccess->mem_event.shared_page == NULL )
- {
- ERROR("Error initialising shared page");
- goto err;
- }
-
/* Initialise ring page */
xenaccess->mem_event.ring_page = init_page();
if ( xenaccess->mem_event.ring_page == NULL )
@@ -242,7 +234,7 @@

/* Initialise Xen */
rc = xc_mem_access_enable(xenaccess->xc_handle, xenaccess->mem_event.domain_id,
- xenaccess->mem_event.shared_page,
+ &xenaccess->mem_event.evtchn_port,
xenaccess->mem_event.ring_page);
if ( rc != 0 )
{
@@ -271,7 +263,7 @@
/* Bind event notification */
rc = xc_evtchn_bind_interdomain(xenaccess->mem_event.xce_handle,
xenaccess->mem_event.domain_id,
- xenaccess->mem_event.shared_page->port);
+ xenaccess->mem_event.evtchn_port);
if ( rc < 0 )
{
ERROR("Failed to bind event channel");
@@ -322,12 +314,6 @@
err:
if ( xenaccess )
{
- if ( xenaccess->mem_event.shared_page )
- {
- munlock(xenaccess->mem_event.shared_page, PAGE_SIZE);
- free(xenaccess->mem_event.shared_page);
- }
-
if ( xenaccess->mem_event.ring_page )
{
munlock(xenaccess->mem_event.ring_page, PAGE_SIZE);
diff -r a8959e0a463f -r e639e75254e9 tools/xenpaging/xenpaging.c
--- a/tools/xenpaging/xenpaging.c Thu Mar 08 17:05:23 2012 +0100
+++ b/tools/xenpaging/xenpaging.c Thu Mar 08 16:40:05 2012 +0000
@@ -337,14 +337,6 @@
goto err;
}

- /* Initialise shared page */
- paging->mem_event.shared_page = init_page();
- if ( paging->mem_event.shared_page == NULL )
- {
- PERROR("Error initialising shared page");
- goto err;
- }
-
/* Initialise ring page */
paging->mem_event.ring_page = init_page();
if ( paging->mem_event.ring_page == NULL )
@@ -361,7 +353,7 @@

/* Initialise Xen */
rc = xc_mem_paging_enable(xch, paging->mem_event.domain_id,
- paging->mem_event.shared_page,
+ &paging->mem_event.evtchn_port,
paging->mem_event.ring_page);
if ( rc != 0 )
{
@@ -393,7 +385,7 @@
/* Bind event notification */
rc = xc_evtchn_bind_interdomain(paging->mem_event.xce_handle,
paging->mem_event.domain_id,
- paging->mem_event.shared_page->port);
+ paging->mem_event.evtchn_port);
if ( rc < 0 )
{
PERROR("Failed to bind event channel");
@@ -474,11 +466,6 @@
munlock(paging->paging_buffer, PAGE_SIZE);
free(paging->paging_buffer);
}
- if ( paging->mem_event.shared_page )
- {
- munlock(paging->mem_event.shared_page, PAGE_SIZE);
- free(paging->mem_event.shared_page);
- }

if ( paging->mem_event.ring_page )
{
diff -r a8959e0a463f -r e639e75254e9 tools/xenpaging/xenpaging.h
--- a/tools/xenpaging/xenpaging.h Thu Mar 08 17:05:23 2012 +0100
+++ b/tools/xenpaging/xenpaging.h Thu Mar 08 16:40:05 2012 +0000
@@ -36,7 +36,7 @@
xc_evtchn *xce_handle;
int port;
mem_event_back_ring_t back_ring;
- mem_event_shared_page_t *shared_page;
+ uint32_t evtchn_port;
void *ring_page;
};

diff -r a8959e0a463f -r e639e75254e9 xen/arch/x86/mm/mem_event.c
--- a/xen/arch/x86/mm/mem_event.c Thu Mar 08 17:05:23 2012 +0100
+++ b/xen/arch/x86/mm/mem_event.c Thu Mar 08 16:40:05 2012 +0000
@@ -50,12 +50,10 @@
struct domain *dom_mem_event = current->domain;
struct vcpu *v = current;
unsigned long ring_addr = mec->ring_addr;
- unsigned long shared_addr = mec->shared_addr;
l1_pgentry_t l1e;
- unsigned long shared_gfn = 0, ring_gfn = 0; /* gcc ... */
+ unsigned long ring_gfn = 0; /* gcc ... */
p2m_type_t p2mt;
mfn_t ring_mfn;
- mfn_t shared_mfn;

/* Only one helper at a time. If the helper crashed,
* the ring is in an undefined state and so is the guest.
@@ -66,10 +64,6 @@
/* Get MFN of ring page */
guest_get_eff_l1e(v, ring_addr, &l1e);
ring_gfn = l1e_get_pfn(l1e);
- /* We're grabbing these two in an order that could deadlock
- * dom0 if 1. it were an hvm 2. there were two concurrent
- * enables 3. the two gfn's in each enable criss-crossed
- * 2MB regions. Duly noted.... */
ring_mfn = get_gfn(dom_mem_event, ring_gfn, &p2mt);

if ( unlikely(!mfn_valid(mfn_x(ring_mfn))) )
@@ -80,23 +74,9 @@

mem_event_ring_lock_init(med);

- /* Get MFN of shared page */
- guest_get_eff_l1e(v, shared_addr, &l1e);
- shared_gfn = l1e_get_pfn(l1e);
- shared_mfn = get_gfn(dom_mem_event, shared_gfn, &p2mt);
-
- if ( unlikely(!mfn_valid(mfn_x(shared_mfn))) )
- {
- put_gfn(dom_mem_event, ring_gfn);
- put_gfn(dom_mem_event, shared_gfn);
- return -EINVAL;
- }
-
- /* Map ring and shared pages */
+ /* Map ring page */
med->ring_page = map_domain_page(mfn_x(ring_mfn));
- med->shared_page = map_domain_page(mfn_x(shared_mfn));
put_gfn(dom_mem_event, ring_gfn);
- put_gfn(dom_mem_event, shared_gfn);

/* Set the number of currently blocked vCPUs to 0. */
med->blocked = 0;
@@ -108,8 +88,7 @@
if ( rc < 0 )
goto err;

- ((mem_event_shared_page_t *)med->shared_page)->port = rc;
- med->xen_port = rc;
+ med->xen_port = mec->port = rc;

/* Prepare ring buffer */
FRONT_RING_INIT(&med->front_ring,
@@ -125,9 +104,6 @@
return 0;

err:
- unmap_domain_page(med->shared_page);
- med->shared_page = NULL;
-
unmap_domain_page(med->ring_page);
med->ring_page = NULL;

@@ -249,9 +225,6 @@
unmap_domain_page(med->ring_page);
med->ring_page = NULL;

- unmap_domain_page(med->shared_page);
- med->shared_page = NULL;
-
/* Unblock all vCPUs */
for_each_vcpu ( d, v )
{
diff -r a8959e0a463f -r e639e75254e9 xen/include/public/domctl.h
--- a/xen/include/public/domctl.h Thu Mar 08 17:05:23 2012 +0100
+++ b/xen/include/public/domctl.h Thu Mar 08 16:40:05 2012 +0000
@@ -747,8 +747,8 @@
uint32_t op; /* XEN_DOMCTL_MEM_EVENT_OP_*_* */
uint32_t mode; /* XEN_DOMCTL_MEM_EVENT_OP_* */

- uint64_aligned_t shared_addr; /* IN: Virtual address of shared page */
- uint64_aligned_t ring_addr; /* IN: Virtual address of ring page */
+ uint32_t port; /* OUT: event channel for ring */
+ uint64_aligned_t ring_addr; /* IN: Virtual address of ring page */
};
typedef struct xen_domctl_mem_event_op xen_domctl_mem_event_op_t;
DEFINE_XEN_GUEST_HANDLE(xen_domctl_mem_event_op_t);
diff -r a8959e0a463f -r e639e75254e9 xen/include/public/mem_event.h
--- a/xen/include/public/mem_event.h Thu Mar 08 17:05:23 2012 +0100
+++ b/xen/include/public/mem_event.h Thu Mar 08 16:40:05 2012 +0000
@@ -46,10 +46,6 @@
#define MEM_EVENT_REASON_INT3 5 /* int3 was hit: gla/gfn are RIP */
#define MEM_EVENT_REASON_SINGLESTEP 6 /* single step was invoked: gla/gfn are RIP */

-typedef struct mem_event_shared_page {
- uint32_t port;
-} mem_event_shared_page_t;
-
typedef struct mem_event_st {
uint32_t flags;
uint32_t vcpu_id;
diff -r a8959e0a463f -r e639e75254e9 xen/include/xen/sched.h
--- a/xen/include/xen/sched.h Thu Mar 08 17:05:23 2012 +0100
+++ b/xen/include/xen/sched.h Thu Mar 08 16:40:05 2012 +0000
@@ -190,8 +190,6 @@
/* The ring has 64 entries */
unsigned char foreign_producers;
unsigned char target_producers;
- /* shared page */
- mem_event_shared_page_t *shared_page;
/* shared ring page */
void *ring_page;
/* front-end ring */

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[xen-unstable] Tools: Remove shared page from mem_event/access/paging interfaces patchbot at xen Mar 9, 2012, 10:44 PM

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