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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH XEN RFC] libxc: use an uncached mapping of guest ram in domain builder
VERY MUCH A WIP.
On ARM guest OSes are started with MMU and Caches disables (as they are on
native) however caching is enabled in the domain running the builder and
therefore we must use an explcitly uncached mapping, otherwise when the guest
starts running it may not see them.
Cache flushes are not sufficient because there is a race between the flush and
the unmap, where the processor may speculatively fill a cache line. Thanks to
Catalin Marinas and Marc Zyngier for pointing this out.
Therefore use the newly introduced IOCTL_PRIVCMD_MMAPBATCH_V2_UNCACHED on ARM
when mapping guest memory from xc_dom_* (which means xc_dom_boot_domU_map in
practice). This avoids issues with the processor dirtying cache lines while
the guest will then fail to see because it starts with MMU and caches
disabled.
The xc_map_foreign_* functions here are a bit of a twisty maze, so far I have
just updated exactly the call path which is used by the function which I
needed to update. I have not yet considered non-xc_linux*.c nor tried to
disentangle this into a saner patch, nor any level of consistency with the
other foreign mapping functions. I've not even tried to compile on x86.
This applies on top of a revert of "tools: libxc: flush data cache after
loading images into guest memory" (a0035ecc0d82) which I will include in the
eventual proper posting.
Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
Cc: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
---
tools/include/xen-sys/Linux/privcmd.h | 2 ++
tools/libxc/xc_core_x86.c | 4 ++--
tools/libxc/xc_dom_boot.c | 2 +-
tools/libxc/xc_domain_restore.c | 4 ++--
tools/libxc/xc_domain_save.c | 4 ++--
tools/libxc/xc_foreign_memory.c | 19 ++++++++++++++-----
tools/libxc/xc_gnttab.c | 2 +-
tools/libxc/xc_linux_osdep.c | 18 +++++++++++++-----
tools/libxc/xc_private.h | 3 +++
tools/libxc/xenctrl.h | 5 +++--
tools/libxc/xenctrl_osdep_ENOSYS.c | 4 ++--
tools/libxc/xenctrlosdep.h | 4 ++--
12 files changed, 47 insertions(+), 24 deletions(-)
diff --git a/tools/include/xen-sys/Linux/privcmd.h
b/tools/include/xen-sys/Linux/privcmd.h
index 5be860a..e3a92a0 100644
--- a/tools/include/xen-sys/Linux/privcmd.h
+++ b/tools/include/xen-sys/Linux/privcmd.h
@@ -88,5 +88,7 @@ typedef struct privcmd_mmapbatch_v2 {
_IOC(_IOC_NONE, 'P', 3, sizeof(privcmd_mmapbatch_t))
#define IOCTL_PRIVCMD_MMAPBATCH_V2 \
_IOC(_IOC_NONE, 'P', 4, sizeof(privcmd_mmapbatch_v2_t))
+#define IOCTL_PRIVCMD_MMAPBATCH_V2_UNCACHED \
+ _IOC(_IOC_NONE, 'P', 5, sizeof(privcmd_mmapbatch_v2_t))
#endif /* __LINUX_PUBLIC_PRIVCMD_H__ */
diff --git a/tools/libxc/xc_core_x86.c b/tools/libxc/xc_core_x86.c
index e328dcf..8e73bc4 100644
--- a/tools/libxc/xc_core_x86.c
+++ b/tools/libxc/xc_core_x86.c
@@ -131,7 +131,7 @@ xc_core_arch_map_p2m_rw(xc_interface *xch, struct
domain_info_context *dinfo, xc
live_p2m_frame_list =
xc_map_foreign_pages(xch, dom, PROT_READ,
p2m_frame_list_list,
- P2M_FLL_ENTRIES);
+ P2M_FLL_ENTRIES, 1);
if ( !live_p2m_frame_list )
{
@@ -159,7 +159,7 @@ xc_core_arch_map_p2m_rw(xc_interface *xch, struct
domain_info_context *dinfo, xc
*live_p2m = xc_map_foreign_pages(xch, dom,
rw ? (PROT_READ | PROT_WRITE) : PROT_READ,
p2m_frame_list,
- P2M_FL_ENTRIES);
+ P2M_FL_ENTRIES, 1);
if ( !*live_p2m )
{
diff --git a/tools/libxc/xc_dom_boot.c b/tools/libxc/xc_dom_boot.c
index fdfeaf8..691fc2b 100644
--- a/tools/libxc/xc_dom_boot.c
+++ b/tools/libxc/xc_dom_boot.c
@@ -179,7 +179,7 @@ void *xc_dom_boot_domU_map(struct xc_dom_image *dom,
xen_pfn_t pfn,
for ( i = 0; i < count; i++ )
entries[i].mfn = xc_dom_p2m_host(dom, pfn + i);
- ptr = xc_map_foreign_ranges(dom->xch, dom->guest_domid,
+ ptr = xc_map_foreign_ranges_uncached(dom->xch, dom->guest_domid,
count << page_shift, PROT_READ | PROT_WRITE, 1 << page_shift,
entries, count);
if ( ptr == NULL )
diff --git a/tools/libxc/xc_domain_restore.c b/tools/libxc/xc_domain_restore.c
index 80769a7..a4c621b 100644
--- a/tools/libxc/xc_domain_restore.c
+++ b/tools/libxc/xc_domain_restore.c
@@ -1885,7 +1885,7 @@ int xc_domain_restore(xc_interface *xch, int io_fd,
uint32_t dom,
if ( (i == (dinfo->p2m_size-1)) || (j == MAX_BATCH_SIZE) )
{
region_base = xc_map_foreign_pages(
- xch, dom, PROT_READ | PROT_WRITE, region_mfn, j);
+ xch, dom, PROT_READ | PROT_WRITE, region_mfn, j, 1);
if ( region_base == NULL )
{
PERROR("map batch failed");
@@ -2222,7 +2222,7 @@ int xc_domain_restore(xc_interface *xch, int io_fd,
uint32_t dom,
/* Copy the P2M we've constructed to the 'live' P2M */
if ( !(ctx->live_p2m = xc_map_foreign_pages(xch, dom, PROT_WRITE,
- p2m_frame_list, P2M_FL_ENTRIES)) )
+ p2m_frame_list,
P2M_FL_ENTRIES, 1)) )
{
PERROR("Couldn't map p2m table");
goto out;
diff --git a/tools/libxc/xc_domain_save.c b/tools/libxc/xc_domain_save.c
index 42c4752..00c97f7 100644
--- a/tools/libxc/xc_domain_save.c
+++ b/tools/libxc/xc_domain_save.c
@@ -631,7 +631,7 @@ static xen_pfn_t *map_and_save_p2m_table(xc_interface *xch,
live_p2m_frame_list =
xc_map_foreign_pages(xch, dom, PROT_READ,
p2m_frame_list_list,
- P2M_FLL_ENTRIES);
+ P2M_FLL_ENTRIES, 1);
if ( !live_p2m_frame_list )
{
PERROR("Couldn't map p2m_frame_list");
@@ -666,7 +666,7 @@ static xen_pfn_t *map_and_save_p2m_table(xc_interface *xch,
p2m = xc_map_foreign_pages(xch, dom, PROT_READ,
p2m_frame_list,
- P2M_FL_ENTRIES);
+ P2M_FL_ENTRIES, 1);
if ( !p2m )
{
PERROR("Couldn't map p2m table");
diff --git a/tools/libxc/xc_foreign_memory.c b/tools/libxc/xc_foreign_memory.c
index 7dfc817..ac4793d 100644
--- a/tools/libxc/xc_foreign_memory.c
+++ b/tools/libxc/xc_foreign_memory.c
@@ -21,7 +21,7 @@
#include "xc_private.h"
void *xc_map_foreign_pages(xc_interface *xch, uint32_t dom, int prot,
- const xen_pfn_t *arr, int num)
+ const xen_pfn_t *arr, int num, int cached)
{
void *res;
int i, *err;
@@ -35,7 +35,7 @@ void *xc_map_foreign_pages(xc_interface *xch, uint32_t dom,
int prot,
if (!err)
return NULL;
- res = xc_map_foreign_bulk(xch, dom, prot, arr, err, num);
+ res = xc_map_foreign_bulk(xch, dom, prot, arr, err, num, cached);
if (res) {
for (i = 0; i < num; i++) {
if (err[i]) {
@@ -63,7 +63,15 @@ void *xc_map_foreign_ranges(xc_interface *xch, uint32_t dom,
privcmd_mmap_entry_t entries[], int nentries)
{
return xch->ops->u.privcmd.map_foreign_ranges(xch, xch->ops_handle,
- dom, size, prot, chunksize,
entries, nentries);
+ dom, size, prot, chunksize,
entries, nentries, 1);
+}
+
+void *xc_map_foreign_ranges_uncached(xc_interface *xch, uint32_t dom,
+ size_t size, int prot, size_t chunksize,
+ privcmd_mmap_entry_t entries[], int nentries)
+{
+ return xch->ops->u.privcmd.map_foreign_ranges(xch, xch->ops_handle,
+ dom, size, prot, chunksize,
entries, nentries, 0);
}
void *xc_map_foreign_batch(xc_interface *xch, uint32_t dom, int prot,
@@ -74,10 +82,11 @@ void *xc_map_foreign_batch(xc_interface *xch, uint32_t dom,
int prot,
}
void *xc_map_foreign_bulk(xc_interface *xch, uint32_t dom, int prot,
- const xen_pfn_t *arr, int *err, unsigned int num)
+ const xen_pfn_t *arr, int *err, unsigned int num,
+ int cached)
{
return xch->ops->u.privcmd.map_foreign_bulk(xch, xch->ops_handle,
- dom, prot, arr, err, num);
+ dom, prot, arr, err, num,
cached);
}
/* stub for all not yet converted OSes */
diff --git a/tools/libxc/xc_gnttab.c b/tools/libxc/xc_gnttab.c
index 79dab40..4774c69 100644
--- a/tools/libxc/xc_gnttab.c
+++ b/tools/libxc/xc_gnttab.c
@@ -114,7 +114,7 @@ static void *_gnttab_map_table(xc_interface *xch, int
domid, int *gnt_num)
pfn_list[i] = frame_list[i];
gnt = xc_map_foreign_pages(xch, domid, PROT_READ, pfn_list,
- setup.nr_frames);
+ setup.nr_frames, 1);
if ( !gnt )
{
ERROR("Could not map grant table\n");
diff --git a/tools/libxc/xc_linux_osdep.c b/tools/libxc/xc_linux_osdep.c
index 73860a2..09aae37 100644
--- a/tools/libxc/xc_linux_osdep.c
+++ b/tools/libxc/xc_linux_osdep.c
@@ -246,7 +246,8 @@ out:
static void *linux_privcmd_map_foreign_bulk(xc_interface *xch, xc_osdep_handle
h,
uint32_t dom, int prot,
- const xen_pfn_t *arr, int *err,
unsigned int num)
+ const xen_pfn_t *arr, int *err,
+ unsigned int num, int cached)
{
int fd = (int)h;
privcmd_mmapbatch_v2_t ioctlx;
@@ -254,6 +255,11 @@ static void *linux_privcmd_map_foreign_bulk(xc_interface
*xch, xc_osdep_handle h
unsigned int i;
int rc;
+#if defined(__i386__) || defined(__x86_64__)
+ /* No need for cache maintenance on x86 */
+ cached = 1;
+#endif
+
addr = mmap(NULL, (unsigned long)num << XC_PAGE_SHIFT, prot, MAP_SHARED,
fd, 0);
if ( addr == MAP_FAILED )
@@ -268,7 +274,9 @@ static void *linux_privcmd_map_foreign_bulk(xc_interface
*xch, xc_osdep_handle h
ioctlx.arr = arr;
ioctlx.err = err;
- rc = ioctl(fd, IOCTL_PRIVCMD_MMAPBATCH_V2, &ioctlx);
+ rc = ioctl(fd, cached ? IOCTL_PRIVCMD_MMAPBATCH_V2
+ : IOCTL_PRIVCMD_MMAPBATCH_V2_UNCACHED,
+ &ioctlx);
/* Command was recognized, some gfn in arr are in paging state */
if ( rc < 0 && errno == ENOENT )
@@ -384,7 +392,7 @@ static void *linux_privcmd_map_foreign_range(xc_interface
*xch, xc_osdep_handle
for ( i = 0; i < num; i++ )
arr[i] = mfn + i;
- ret = xc_map_foreign_pages(xch, dom, prot, arr, num);
+ ret = xc_map_foreign_pages(xch, dom, prot, arr, num, 1);
free(arr);
return ret;
}
@@ -392,7 +400,7 @@ static void *linux_privcmd_map_foreign_range(xc_interface
*xch, xc_osdep_handle
static void *linux_privcmd_map_foreign_ranges(xc_interface *xch,
xc_osdep_handle h,
uint32_t dom, size_t size, int
prot,
size_t chunksize,
privcmd_mmap_entry_t entries[],
- int nentries)
+ int nentries, int cached)
{
xen_pfn_t *arr;
int num_per_entry;
@@ -411,7 +419,7 @@ static void *linux_privcmd_map_foreign_ranges(xc_interface
*xch, xc_osdep_handle
for ( j = 0; j < num_per_entry; j++ )
arr[i * num_per_entry + j] = entries[i].mfn + j;
- ret = xc_map_foreign_pages(xch, dom, prot, arr, num);
+ ret = xc_map_foreign_pages(xch, dom, prot, arr, num, 1);
free(arr);
return ret;
}
diff --git a/tools/libxc/xc_private.h b/tools/libxc/xc_private.h
index 92271c9..e040179 100644
--- a/tools/libxc/xc_private.h
+++ b/tools/libxc/xc_private.h
@@ -294,6 +294,9 @@ int do_memory_op(xc_interface *xch, int cmd, void *arg,
size_t len);
void *xc_map_foreign_ranges(xc_interface *xch, uint32_t dom,
size_t size, int prot, size_t chunksize,
privcmd_mmap_entry_t entries[], int nentries);
+void *xc_map_foreign_ranges_uncached(xc_interface *xch, uint32_t dom,
+ size_t size, int prot, size_t chunksize,
+ privcmd_mmap_entry_t entries[], int nentries);
int xc_get_pfn_type_batch(xc_interface *xch, uint32_t dom,
unsigned int num, xen_pfn_t *);
diff --git a/tools/libxc/xenctrl.h b/tools/libxc/xenctrl.h
index 6e58ebe..b20731c 100644
--- a/tools/libxc/xenctrl.h
+++ b/tools/libxc/xenctrl.h
@@ -1324,7 +1324,7 @@ void *xc_map_foreign_range(xc_interface *xch, uint32_t
dom,
unsigned long mfn );
void *xc_map_foreign_pages(xc_interface *xch, uint32_t dom, int prot,
- const xen_pfn_t *arr, int num );
+ const xen_pfn_t *arr, int num, int cached);
/**
* DEPRECATED - use xc_map_foreign_bulk() instead.
@@ -1342,7 +1342,8 @@ void *xc_map_foreign_batch(xc_interface *xch, uint32_t
dom, int prot,
* set to the corresponding errno value.
*/
void *xc_map_foreign_bulk(xc_interface *xch, uint32_t dom, int prot,
- const xen_pfn_t *arr, int *err, unsigned int num);
+ const xen_pfn_t *arr, int *err, unsigned int num,
+ int cached);
/**
* Translates a virtual address in the context of a given domain and
diff --git a/tools/libxc/xenctrl_osdep_ENOSYS.c
b/tools/libxc/xenctrl_osdep_ENOSYS.c
index 4821342..d26c696 100644
--- a/tools/libxc/xenctrl_osdep_ENOSYS.c
+++ b/tools/libxc/xenctrl_osdep_ENOSYS.c
@@ -42,7 +42,7 @@ static void *ENOSYS_privcmd_map_foreign_batch(xc_interface
*xch, xc_osdep_handle
}
static void *ENOSYS_privcmd_map_foreign_bulk(xc_interface *xch,
xc_osdep_handle h, uint32_t dom, int prot,
- const xen_pfn_t *arr, int *err, unsigned
int num)
+ const xen_pfn_t *arr, int *err, unsigned
int num, int cached)
{
IPRINTF(xch, "ENOSYS_privcmd %p: map_foreign_buld: dom%d prot %#x arr %p
err %p num %d\n", h, dom, prot, arr, err, num);
return MAP_FAILED;
@@ -57,7 +57,7 @@ static void *ENOSYS_privcmd_map_foreign_range(xc_interface
*xch, xc_osdep_handle
static void *ENOSYS_privcmd_map_foreign_ranges(xc_interface *xch,
xc_osdep_handle h, uint32_t dom, size_t size, int prot,
size_t chunksize, privcmd_mmap_entry_t
entries[],
- int nentries)
+ int nentries, int cached)
{
IPRINTF(xch, "ENOSYS_privcmd %p: map_foreign_ranges: dom%d size %zd prot
%#x chunksize %zd entries %p num %d\n", h, dom, size, prot, chunksize, entries,
nentries);
return MAP_FAILED;
diff --git a/tools/libxc/xenctrlosdep.h b/tools/libxc/xenctrlosdep.h
index e610a24..3daf757 100644
--- a/tools/libxc/xenctrlosdep.h
+++ b/tools/libxc/xenctrlosdep.h
@@ -83,12 +83,12 @@ struct xc_osdep_ops
void *(*map_foreign_batch)(xc_interface *xch, xc_osdep_handle h,
uint32_t dom, int prot,
xen_pfn_t *arr, int num);
void *(*map_foreign_bulk)(xc_interface *xch, xc_osdep_handle h,
uint32_t dom, int prot,
- const xen_pfn_t *arr, int *err, unsigned
int num);
+ const xen_pfn_t *arr, int *err, unsigned
int num, int cached);
void *(*map_foreign_range)(xc_interface *xch, xc_osdep_handle h,
uint32_t dom, int size, int prot,
unsigned long mfn);
void *(*map_foreign_ranges)(xc_interface *xch, xc_osdep_handle h,
uint32_t dom, size_t size, int prot,
size_t chunksize, privcmd_mmap_entry_t
entries[],
- int nentries);
+ int nentries, int cached);
} privcmd;
struct {
int (*fd)(xc_evtchn *xce, xc_osdep_handle h);
--
1.7.10.4
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