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Re: [Qemu-devel] [PATCH v2 3/4] xen/mapcache: introduce xen_replace_cach
From: |
Paul Durrant |
Subject: |
Re: [Qemu-devel] [PATCH v2 3/4] xen/mapcache: introduce xen_replace_cache_entry() |
Date: |
Tue, 4 Jul 2017 16:42:21 +0000 |
> -----Original Message-----
> From: Igor Druzhinin
> Sent: 04 July 2017 17:34
> To: Paul Durrant <address@hidden>; address@hidden;
> address@hidden
> Cc: address@hidden; Anthony Perard <address@hidden>;
> address@hidden
> Subject: Re: [PATCH v2 3/4] xen/mapcache: introduce
> xen_replace_cache_entry()
>
> On 04/07/17 17:27, Paul Durrant wrote:
> >> -----Original Message-----
> >> From: Igor Druzhinin
> >> Sent: 04 July 2017 16:48
> >> To: address@hidden; address@hidden
> >> Cc: Igor Druzhinin <address@hidden>; address@hidden;
> >> Anthony Perard <address@hidden>; Paul Durrant
> >> <address@hidden>; address@hidden
> >> Subject: [PATCH v2 3/4] xen/mapcache: introduce
> >> xen_replace_cache_entry()
> >>
> >> This new call is trying to update a requested map cache entry
> >> according to the changes in the physmap. The call is searching
> >> for the entry, unmaps it and maps again at the same place using
> >> a new guest address. If the mapping is dummy this call will
> >> make it real.
> >>
> >> This function makes use of a new xenforeignmemory_map2() call
> >> with an extended interface that was recently introduced in
> >> libxenforeignmemory [1].
> >
> > I don't understand how the compat layer works here. If
> xenforeignmemory_map2() is not available then you can't control the
> placement in virtual address space.
> >
>
> If it's not 4.10 or newer xenforeignmemory_map2() doesn't exist and is
> going to be defined as xenforeignmemory_map(). At the same time
> XEN_COMPAT_PHYSMAP is defined and the entry replace function (which
> relies on xenforeignmemory_map2 functionality) is never going to be called.
>
> If you mean that I should incorporate this into the description I can do it.
AFAICT XEN_COMPAT_PHYSMAP is not introduced until patch #4 though.
The problem really comes down to defining xenforeignmemory_map2() in terms of
xenforeignmemory_map(). It basically can't be safely done. Could you define
xenforeignmemory_map2() as abort() in the compat case instead?
Paul
>
> Igor
>
> > Paul
> >
> >>
> >> [1] https://www.mail-archive.com/xen-
> address@hidden/msg113007.html
> >>
> >> Signed-off-by: Igor Druzhinin <address@hidden>
> >> ---
> >> configure | 18 ++++++++++
> >> hw/i386/xen/xen-mapcache.c | 79
> >> ++++++++++++++++++++++++++++++++++++++-----
> >> include/hw/xen/xen_common.h | 7 ++++
> >> include/sysemu/xen-mapcache.h | 11 +++++-
> >> 4 files changed, 106 insertions(+), 9 deletions(-)
> >>
> >> diff --git a/configure b/configure
> >> index c571ad1..ad6156b 100755
> >> --- a/configure
> >> +++ b/configure
> >> @@ -2021,6 +2021,24 @@ EOF
> >> # Xen unstable
> >> elif
> >> cat > $TMPC <<EOF &&
> >> +#undef XC_WANT_COMPAT_MAP_FOREIGN_API
> >> +#include <xenforeignmemory.h>
> >> +int main(void) {
> >> + xenforeignmemory_handle *xfmem;
> >> +
> >> + xfmem = xenforeignmemory_open(0, 0);
> >> + xenforeignmemory_map2(xfmem, 0, 0, 0, 0, 0, 0, 0);
> >> +
> >> + return 0;
> >> +}
> >> +EOF
> >> + compile_prog "" "$xen_libs -lxendevicemodel $xen_stable_libs"
> >> + then
> >> + xen_stable_libs="-lxendevicemodel $xen_stable_libs"
> >> + xen_ctrl_version=41000
> >> + xen=yes
> >> + elif
> >> + cat > $TMPC <<EOF &&
> >> #undef XC_WANT_COMPAT_DEVICEMODEL_API
> >> #define __XEN_TOOLS__
> >> #include <xendevicemodel.h>
> >> diff --git a/hw/i386/xen/xen-mapcache.c b/hw/i386/xen/xen-mapcache.c
> >> index cd4e746..a988be7 100644
> >> --- a/hw/i386/xen/xen-mapcache.c
> >> +++ b/hw/i386/xen/xen-mapcache.c
> >> @@ -151,6 +151,7 @@ void
> xen_map_cache_init(phys_offset_to_gaddr_t f,
> >> void *opaque)
> >> }
> >>
> >> static void xen_remap_bucket(MapCacheEntry *entry,
> >> + void *vaddr,
> >> hwaddr size,
> >> hwaddr address_index,
> >> bool dummy)
> >> @@ -167,7 +168,9 @@ static void xen_remap_bucket(MapCacheEntry
> >> *entry,
> >> err = g_malloc0(nb_pfn * sizeof (int));
> >>
> >> if (entry->vaddr_base != NULL) {
> >> - ram_block_notify_remove(entry->vaddr_base, entry->size);
> >> + if (entry->vaddr_base != vaddr) {
> >> + ram_block_notify_remove(entry->vaddr_base, entry->size);
> >> + }
> >> if (munmap(entry->vaddr_base, entry->size) != 0) {
> >> perror("unmap fails");
> >> exit(-1);
> >> @@ -181,11 +184,11 @@ static void xen_remap_bucket(MapCacheEntry
> >> *entry,
> >> }
> >>
> >> if (!dummy) {
> >> - vaddr_base = xenforeignmemory_map(xen_fmem, xen_domid,
> >> - PROT_READ|PROT_WRITE,
> >> + vaddr_base = xenforeignmemory_map2(xen_fmem, xen_domid,
> >> vaddr,
> >> + PROT_READ|PROT_WRITE, 0,
> >> nb_pfn, pfns, err);
> >> if (vaddr_base == NULL) {
> >> - perror("xenforeignmemory_map");
> >> + perror("xenforeignmemory_map2");
> >> exit(-1);
> >> }
> >> entry->flags &= ~(XEN_MAPCACHE_ENTRY_DUMMY);
> >> @@ -194,7 +197,7 @@ static void xen_remap_bucket(MapCacheEntry
> >> *entry,
> >> * We create dummy mappings where we are unable to create a
> foreign
> >> * mapping immediately due to certain circumstances (i.e. on
> >> resume
> >> now)
> >> */
> >> - vaddr_base = mmap(NULL, size, PROT_READ|PROT_WRITE,
> >> + vaddr_base = mmap(vaddr, size, PROT_READ|PROT_WRITE,
> >> MAP_ANON|MAP_SHARED, -1, 0);
> >> if (vaddr_base == NULL) {
> >> perror("mmap");
> >> @@ -203,13 +206,16 @@ static void xen_remap_bucket(MapCacheEntry
> >> *entry,
> >> entry->flags |= XEN_MAPCACHE_ENTRY_DUMMY;
> >> }
> >>
> >> + if (entry->vaddr_base == NULL || entry->vaddr_base != vaddr) {
> >> + ram_block_notify_add(vaddr_base, size);
> >> + }
> >> +
> >> entry->vaddr_base = vaddr_base;
> >> entry->paddr_index = address_index;
> >> entry->size = size;
> >> entry->valid_mapping = (unsigned long *) g_malloc0(sizeof(unsigned
> long)
> >> *
> >> BITS_TO_LONGS(size >> XC_PAGE_SHIFT));
> >>
> >> - ram_block_notify_add(entry->vaddr_base, entry->size);
> >> bitmap_zero(entry->valid_mapping, nb_pfn);
> >> for (i = 0; i < nb_pfn; i++) {
> >> if (!err[i]) {
> >> @@ -282,14 +288,14 @@ tryagain:
> >> if (!entry) {
> >> entry = g_malloc0(sizeof (MapCacheEntry));
> >> pentry->next = entry;
> >> - xen_remap_bucket(entry, cache_size, address_index, dummy);
> >> + xen_remap_bucket(entry, NULL, cache_size, address_index,
> dummy);
> >> } else if (!entry->lock) {
> >> if (!entry->vaddr_base || entry->paddr_index != address_index ||
> >> entry->size != cache_size ||
> >> !test_bits(address_offset >> XC_PAGE_SHIFT,
> >> test_bit_size >> XC_PAGE_SHIFT,
> >> entry->valid_mapping)) {
> >> - xen_remap_bucket(entry, cache_size, address_index, dummy);
> >> + xen_remap_bucket(entry, NULL, cache_size, address_index,
> >> dummy);
> >> }
> >> }
> >>
> >> @@ -486,3 +492,60 @@ void xen_invalidate_map_cache(void)
> >>
> >> mapcache_unlock();
> >> }
> >> +
> >> +static uint8_t *xen_replace_cache_entry_unlocked(hwaddr
> >> old_phys_addr,
> >> + hwaddr new_phys_addr,
> >> + hwaddr size)
> >> +{
> >> + MapCacheEntry *entry;
> >> + hwaddr address_index;
> >> + hwaddr address_offset;
> >> + hwaddr cache_size = size;
> >> + hwaddr test_bit_size;
> >> +
> >> + address_index = old_phys_addr >> MCACHE_BUCKET_SHIFT;
> >> + address_offset = old_phys_addr & (MCACHE_BUCKET_SIZE - 1);
> >> +
> >> + assert(size);
> >> + /* test_bit_size is always a multiple of XC_PAGE_SIZE */
> >> + test_bit_size = size + (old_phys_addr & (XC_PAGE_SIZE - 1));
> >> + if (test_bit_size % XC_PAGE_SIZE) {
> >> + test_bit_size += XC_PAGE_SIZE - (test_bit_size % XC_PAGE_SIZE);
> >> + }
> >> + cache_size = size + address_offset;
> >> + if (cache_size % MCACHE_BUCKET_SIZE) {
> >> + cache_size += MCACHE_BUCKET_SIZE - (cache_size %
> >> MCACHE_BUCKET_SIZE);
> >> + }
> >> +
> >> + entry = &mapcache->entry[address_index % mapcache->nr_buckets];
> >> + while (entry && !(entry->paddr_index == address_index && entry-
> >size
> >> == cache_size)) {
> >> + entry = entry->next;
> >> + }
> >> + if (!entry) {
> >> + DPRINTF("Trying to update an entry for %lx that is not in the
> >> mapcache!\n", phys_addr);
> >> + return NULL;
> >> + }
> >> +
> >> + address_index = new_phys_addr >> MCACHE_BUCKET_SHIFT;
> >> + address_offset = new_phys_addr & (MCACHE_BUCKET_SIZE - 1);
> >> +
> >> + xen_remap_bucket(entry, entry->vaddr_base, cache_size,
> >> address_index, false);
> >> + if(!test_bits(address_offset >> XC_PAGE_SHIFT,
> >> + test_bit_size >> XC_PAGE_SHIFT,
> >> + entry->valid_mapping)) {
> >> + DPRINTF("Unable to update an entry for %lx in the mapcache!\n",
> >> phys_addr);
> >> + return NULL;
> >> + }
> >> +
> >> + return entry->vaddr_base + address_offset;
> >> +}
> >> +
> >> +uint8_t *xen_replace_cache_entry(hwaddr old_phys_addr, hwaddr
> >> new_phys_addr, hwaddr size)
> >> +{
> >> + uint8_t *p;
> >> +
> >> + mapcache_lock();
> >> + p = xen_replace_cache_entry_unlocked(old_phys_addr,
> >> new_phys_addr, size);
> >> + mapcache_unlock();
> >> + return p;
> >> +}
> >> diff --git a/include/hw/xen/xen_common.h
> >> b/include/hw/xen/xen_common.h
> >> index e00ddd7..70a5cad 100644
> >> --- a/include/hw/xen/xen_common.h
> >> +++ b/include/hw/xen/xen_common.h
> >> @@ -78,6 +78,13 @@ static inline void
> >> *xenforeignmemory_map(xc_interface *h, uint32_t dom,
> >>
> >> extern xenforeignmemory_handle *xen_fmem;
> >>
> >> +#if CONFIG_XEN_CTRL_INTERFACE_VERSION < 41000
> >> +
> >> +#define xenforeignmemory_map2(h, d, a, p, f, ps, ar, e) \
> >> + xenforeignmemory_map(h, d, p, ps, ar, e)
> >> +
> >> +#endif
> >> +
> >> #if CONFIG_XEN_CTRL_INTERFACE_VERSION < 40900
> >>
> >> typedef xc_interface xendevicemodel_handle;
> >> diff --git a/include/sysemu/xen-mapcache.h b/include/sysemu/xen-
> >> mapcache.h
> >> index 01daaad..b38962c 100644
> >> --- a/include/sysemu/xen-mapcache.h
> >> +++ b/include/sysemu/xen-mapcache.h
> >> @@ -21,7 +21,9 @@ uint8_t *xen_map_cache(hwaddr phys_addr,
> hwaddr
> >> size,
> >> ram_addr_t xen_ram_addr_from_mapcache(void *ptr);
> >> void xen_invalidate_map_cache_entry(uint8_t *buffer);
> >> void xen_invalidate_map_cache(void);
> >> -
> >> +uint8_t *xen_replace_cache_entry(hwaddr old_phys_addr,
> >> + hwaddr new_phys_addr,
> >> + hwaddr size);
> >> #else
> >>
> >> static inline void xen_map_cache_init(phys_offset_to_gaddr_t f,
> >> @@ -50,6 +52,13 @@ static inline void xen_invalidate_map_cache(void)
> >> {
> >> }
> >>
> >> +uint8_t *xen_replace_cache_entry(hwaddr old_phys_addr,
> >> + hwaddr new_phys_addr,
> >> + hwaddr size)
> >> +{
> >> + abort();
> >> +}
> >> +
> >> #endif
> >>
> >> #endif /* XEN_MAPCACHE_H */
> >> --
> >> 2.7.4
> >
- [Qemu-devel] [PATCH v2 0/4] xen: don't save/restore the physmap on VM save/restore, Igor Druzhinin, 2017/07/04
- [Qemu-devel] [PATCH v2 1/4] xen: move physmap saving into a separate function, Igor Druzhinin, 2017/07/04
- [Qemu-devel] [PATCH v2 2/4] xen/mapcache: add an ability to create dummy mappings, Igor Druzhinin, 2017/07/04
- [Qemu-devel] [PATCH v2 3/4] xen/mapcache: introduce xen_replace_cache_entry(), Igor Druzhinin, 2017/07/04
- Re: [Qemu-devel] [PATCH v2 3/4] xen/mapcache: introduce xen_replace_cache_entry(), Paul Durrant, 2017/07/04
- Re: [Qemu-devel] [PATCH v2 3/4] xen/mapcache: introduce xen_replace_cache_entry(), Igor Druzhinin, 2017/07/04
- Re: [Qemu-devel] [PATCH v2 3/4] xen/mapcache: introduce xen_replace_cache_entry(),
Paul Durrant <=
- Re: [Qemu-devel] [PATCH v2 3/4] xen/mapcache: introduce xen_replace_cache_entry(), Igor Druzhinin, 2017/07/04
- Re: [Qemu-devel] [PATCH v2 3/4] xen/mapcache: introduce xen_replace_cache_entry(), Paul Durrant, 2017/07/05
- Re: [Qemu-devel] [PATCH v2 3/4] xen/mapcache: introduce xen_replace_cache_entry(), Stefano Stabellini, 2017/07/05
- Re: [Qemu-devel] [PATCH v2 3/4] xen/mapcache: introduce xen_replace_cache_entry(), Paul Durrant, 2017/07/06
Re: [Qemu-devel] [PATCH v2 3/4] xen/mapcache: introduce xen_replace_cache_entry(), Stefano Stabellini, 2017/07/05
[Qemu-devel] [PATCH v2 4/4] xen: don't use xenstore to save/restore physmap anymore, Igor Druzhinin, 2017/07/04
Re: [Qemu-devel] [PATCH v2 0/4] xen: don't save/restore the physmap on VM save/restore, no-reply, 2017/07/06