Message ID | 20170206173306.20603-5-dgilbert@redhat.com |
---|---|
State | New |
Headers | show |
"Dr. David Alan Gilbert (git)" <dgilbert@redhat.com> wrote: > From: "Dr. David Alan Gilbert" <dgilbert@redhat.com> > > Create ram_block_discard_range in exec.c to replace > postcopy_ram_discard_range and most of ram_discard_range. > > Those two routines are a bit of a weird combination, and > ram_discard_range is about to get more complex for hugepages. > It's OS dependent code (so shouldn't be in migration/ram.c) but > it needs quite a bit of the innards of RAMBlock so doesn't belong in > the os*.c. > > Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com> Reviewed-by: Juan Quintela <quintela@redhat.com>
On 06/02/2017 18:32, Dr. David Alan Gilbert (git) wrote: > From: "Dr. David Alan Gilbert" <dgilbert@redhat.com> > > Create ram_block_discard_range in exec.c to replace > postcopy_ram_discard_range and most of ram_discard_range. > > Those two routines are a bit of a weird combination, and > ram_discard_range is about to get more complex for hugepages. > It's OS dependent code (so shouldn't be in migration/ram.c) but > it needs quite a bit of the innards of RAMBlock so doesn't belong in > the os*.c. > > Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com> > --- > exec.c | 59 +++++++++++++++++++++++++++++++++++++++++++++++ > include/exec/cpu-common.h | 1 + > 2 files changed, 60 insertions(+) > > diff --git a/exec.c b/exec.c > index 8b9ed73..e040cdf 100644 > --- a/exec.c > +++ b/exec.c > @@ -45,6 +45,12 @@ > #include "exec/address-spaces.h" > #include "sysemu/xen-mapcache.h" > #include "trace-root.h" > + > +#ifdef CONFIG_FALLOCATE_PUNCH_HOLE > +#include <fcntl.h> > +#include <linux/falloc.h> > +#endif > + > #endif > #include "exec/cpu-all.h" > #include "qemu/rcu_queue.h" > @@ -3286,4 +3292,57 @@ int qemu_ram_foreach_block(RAMBlockIterFunc func, void *opaque) > rcu_read_unlock(); > return ret; > } > + > +/* > + * Unmap pages of memory from start to start+length such that > + * they a) read as 0, b) Trigger whatever fault mechanism > + * the OS provides for postcopy. > + * The pages must be unmapped by the end of the function. > + * Returns: 0 on success, none-0 on failure > + * > + */ > +int ram_block_discard_range(RAMBlock *rb, uint64_t start, size_t length) > +{ > + int ret = -1; > + > + rcu_read_lock(); > + uint8_t *host_startaddr = rb->host + start; > + > + if ((uintptr_t)host_startaddr & (rb->page_size - 1)) { > + error_report("ram_block_discard_range: Unaligned start address: %p", > + host_startaddr); > + goto err; > + } > + > + if ((start + length) <= rb->used_length) { > + uint8_t *host_endaddr = host_startaddr + length; > + if ((uintptr_t)host_endaddr & (rb->page_size - 1)) { > + error_report("ram_block_discard_range: Unaligned end address: %p", > + host_endaddr); > + goto err; > + } > + > + errno = ENOTSUP; /* If we are missing MADVISE etc */ > + > +#if defined(CONFIG_MADVISE) > + ret = qemu_madvise(host_startaddr, length, QEMU_MADV_DONTNEED); > +#endif > + if (ret) { > + ret = -errno; > + error_report("ram_block_discard_range: Failed to discard range " > + "%s:%" PRIx64 " +%zx (%d)", > + rb->idstr, start, length, ret); > + } > + } else { > + error_report("ram_block_discard_range: Overrun block '%s' (%" PRIu64 > + "/%zx/" RAM_ADDR_FMT")", > + rb->idstr, start, length, rb->used_length); > + } > + > +err: > + rcu_read_unlock(); > + > + return ret; > +} I really looks like a copy'n'paste from ram_discard_range(). It could be clearer if you remove the code from ram_discard_range() and call this function instead. I think you don't need the "#if defined(CONFIG_MADVISE)" as you use qemu_madvise() (or you should use madvise() directly if you want to avoid the posix_madvise()). [perhaps qemu_madvise() should set errno to ENOTSUP instead of EINVAL] Laurent
On 06/02/2017 18:32, Dr. David Alan Gilbert (git) wrote: > From: "Dr. David Alan Gilbert" <dgilbert@redhat.com> > > Create ram_block_discard_range in exec.c to replace > postcopy_ram_discard_range and most of ram_discard_range. > > Those two routines are a bit of a weird combination, and > ram_discard_range is about to get more complex for hugepages. > It's OS dependent code (so shouldn't be in migration/ram.c) but > it needs quite a bit of the innards of RAMBlock so doesn't belong in > the os*.c. > > Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com> > --- > exec.c | 59 +++++++++++++++++++++++++++++++++++++++++++++++ > include/exec/cpu-common.h | 1 + > 2 files changed, 60 insertions(+) > > diff --git a/exec.c b/exec.c > index 8b9ed73..e040cdf 100644 > --- a/exec.c > +++ b/exec.c > @@ -45,6 +45,12 @@ > #include "exec/address-spaces.h" > #include "sysemu/xen-mapcache.h" > #include "trace-root.h" > + > +#ifdef CONFIG_FALLOCATE_PUNCH_HOLE > +#include <fcntl.h> > +#include <linux/falloc.h> > +#endif Should it be in PATCH 05/16 instead? Laurent
* Laurent Vivier (lvivier@redhat.com) wrote: > On 06/02/2017 18:32, Dr. David Alan Gilbert (git) wrote: > > From: "Dr. David Alan Gilbert" <dgilbert@redhat.com> > > > > Create ram_block_discard_range in exec.c to replace > > postcopy_ram_discard_range and most of ram_discard_range. > > > > Those two routines are a bit of a weird combination, and > > ram_discard_range is about to get more complex for hugepages. > > It's OS dependent code (so shouldn't be in migration/ram.c) but > > it needs quite a bit of the innards of RAMBlock so doesn't belong in > > the os*.c. > > > > Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com> > > --- > > exec.c | 59 +++++++++++++++++++++++++++++++++++++++++++++++ > > include/exec/cpu-common.h | 1 + > > 2 files changed, 60 insertions(+) > > > > diff --git a/exec.c b/exec.c > > index 8b9ed73..e040cdf 100644 > > --- a/exec.c > > +++ b/exec.c > > @@ -45,6 +45,12 @@ > > #include "exec/address-spaces.h" > > #include "sysemu/xen-mapcache.h" > > #include "trace-root.h" > > + > > +#ifdef CONFIG_FALLOCATE_PUNCH_HOLE > > +#include <fcntl.h> > > +#include <linux/falloc.h> > > +#endif > > Should it be in PATCH 05/16 instead? Ah, yes, it should. Dave > Laurent > -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
* Laurent Vivier (lvivier@redhat.com) wrote: > On 06/02/2017 18:32, Dr. David Alan Gilbert (git) wrote: > > From: "Dr. David Alan Gilbert" <dgilbert@redhat.com> > > > > Create ram_block_discard_range in exec.c to replace > > postcopy_ram_discard_range and most of ram_discard_range. > > > > Those two routines are a bit of a weird combination, and > > ram_discard_range is about to get more complex for hugepages. > > It's OS dependent code (so shouldn't be in migration/ram.c) but > > it needs quite a bit of the innards of RAMBlock so doesn't belong in > > the os*.c. > > > > Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com> > > --- > > exec.c | 59 +++++++++++++++++++++++++++++++++++++++++++++++ > > include/exec/cpu-common.h | 1 + > > 2 files changed, 60 insertions(+) > > > > diff --git a/exec.c b/exec.c > > index 8b9ed73..e040cdf 100644 > > --- a/exec.c > > +++ b/exec.c > > @@ -45,6 +45,12 @@ > > #include "exec/address-spaces.h" > > #include "sysemu/xen-mapcache.h" > > #include "trace-root.h" > > + > > +#ifdef CONFIG_FALLOCATE_PUNCH_HOLE > > +#include <fcntl.h> > > +#include <linux/falloc.h> > > +#endif > > + > > #endif > > #include "exec/cpu-all.h" > > #include "qemu/rcu_queue.h" > > @@ -3286,4 +3292,57 @@ int qemu_ram_foreach_block(RAMBlockIterFunc func, void *opaque) > > rcu_read_unlock(); > > return ret; > > } > > + > > +/* > > + * Unmap pages of memory from start to start+length such that > > + * they a) read as 0, b) Trigger whatever fault mechanism > > + * the OS provides for postcopy. > > + * The pages must be unmapped by the end of the function. > > + * Returns: 0 on success, none-0 on failure > > + * > > + */ > > +int ram_block_discard_range(RAMBlock *rb, uint64_t start, size_t length) > > +{ > > + int ret = -1; > > + > > + rcu_read_lock(); > > + uint8_t *host_startaddr = rb->host + start; > > + > > + if ((uintptr_t)host_startaddr & (rb->page_size - 1)) { > > + error_report("ram_block_discard_range: Unaligned start address: %p", > > + host_startaddr); > > + goto err; > > + } > > + > > + if ((start + length) <= rb->used_length) { > > + uint8_t *host_endaddr = host_startaddr + length; > > + if ((uintptr_t)host_endaddr & (rb->page_size - 1)) { > > + error_report("ram_block_discard_range: Unaligned end address: %p", > > + host_endaddr); > > + goto err; > > + } > > + > > + errno = ENOTSUP; /* If we are missing MADVISE etc */ > > + > > +#if defined(CONFIG_MADVISE) > > + ret = qemu_madvise(host_startaddr, length, QEMU_MADV_DONTNEED); > > +#endif > > + if (ret) { > > + ret = -errno; > > + error_report("ram_block_discard_range: Failed to discard range " > > + "%s:%" PRIx64 " +%zx (%d)", > > + rb->idstr, start, length, ret); > > + } > > + } else { > > + error_report("ram_block_discard_range: Overrun block '%s' (%" PRIu64 > > + "/%zx/" RAM_ADDR_FMT")", > > + rb->idstr, start, length, rb->used_length); > > + } > > + > > +err: > > + rcu_read_unlock(); > > + > > + return ret; > > +} > > I really looks like a copy'n'paste from ram_discard_range(). It could be > clearer if you remove the code from ram_discard_range() and call this > function instead. Yes, flattened into the latter commit. > I think you don't need the "#if defined(CONFIG_MADVISE)" as you use > qemu_madvise() (or you should use madvise() directly if you want to > avoid the posix_madvise()). Yes, changed to CONFIG_MADVISE + madvise() I need to avoid posix_madvise because it doesn't do the same thing. > [perhaps qemu_madvise() should set errno to ENOTSUP instead of EINVAL] The difficulty is with how it fiddles with it's QEMU_MADV_* macros, when it finds one that doesn't exist it gets defined as -1 or the like which then fails that way. Dave > > Laurent -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
diff --git a/exec.c b/exec.c index 8b9ed73..e040cdf 100644 --- a/exec.c +++ b/exec.c @@ -45,6 +45,12 @@ #include "exec/address-spaces.h" #include "sysemu/xen-mapcache.h" #include "trace-root.h" + +#ifdef CONFIG_FALLOCATE_PUNCH_HOLE +#include <fcntl.h> +#include <linux/falloc.h> +#endif + #endif #include "exec/cpu-all.h" #include "qemu/rcu_queue.h" @@ -3286,4 +3292,57 @@ int qemu_ram_foreach_block(RAMBlockIterFunc func, void *opaque) rcu_read_unlock(); return ret; } + +/* + * Unmap pages of memory from start to start+length such that + * they a) read as 0, b) Trigger whatever fault mechanism + * the OS provides for postcopy. + * The pages must be unmapped by the end of the function. + * Returns: 0 on success, none-0 on failure + * + */ +int ram_block_discard_range(RAMBlock *rb, uint64_t start, size_t length) +{ + int ret = -1; + + rcu_read_lock(); + uint8_t *host_startaddr = rb->host + start; + + if ((uintptr_t)host_startaddr & (rb->page_size - 1)) { + error_report("ram_block_discard_range: Unaligned start address: %p", + host_startaddr); + goto err; + } + + if ((start + length) <= rb->used_length) { + uint8_t *host_endaddr = host_startaddr + length; + if ((uintptr_t)host_endaddr & (rb->page_size - 1)) { + error_report("ram_block_discard_range: Unaligned end address: %p", + host_endaddr); + goto err; + } + + errno = ENOTSUP; /* If we are missing MADVISE etc */ + +#if defined(CONFIG_MADVISE) + ret = qemu_madvise(host_startaddr, length, QEMU_MADV_DONTNEED); +#endif + if (ret) { + ret = -errno; + error_report("ram_block_discard_range: Failed to discard range " + "%s:%" PRIx64 " +%zx (%d)", + rb->idstr, start, length, ret); + } + } else { + error_report("ram_block_discard_range: Overrun block '%s' (%" PRIu64 + "/%zx/" RAM_ADDR_FMT")", + rb->idstr, start, length, rb->used_length); + } + +err: + rcu_read_unlock(); + + return ret; +} + #endif diff --git a/include/exec/cpu-common.h b/include/exec/cpu-common.h index bd15853..1350c2e 100644 --- a/include/exec/cpu-common.h +++ b/include/exec/cpu-common.h @@ -105,6 +105,7 @@ typedef int (RAMBlockIterFunc)(const char *block_name, void *host_addr, ram_addr_t offset, ram_addr_t length, void *opaque); int qemu_ram_foreach_block(RAMBlockIterFunc func, void *opaque); +int ram_block_discard_range(RAMBlock *rb, uint64_t start, size_t length); #endif