[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH v12 5/6] x86/ioreq server: Asynchronously reset outstanding p2m_ioreq_server entries.
On 06/04/17 16:53, Yu Zhang wrote: > After an ioreq server has unmapped, the remaining p2m_ioreq_server > entries need to be reset back to p2m_ram_rw. This patch does this > asynchronously with the current p2m_change_entry_type_global() > interface. > > New field entry_count is introduced in struct p2m_domain, to record > the number of p2m_ioreq_server p2m page table entries. One nature of > these entries is that they only point to 4K sized page frames, because > all p2m_ioreq_server entries are originated from p2m_ram_rw ones in > p2m_change_type_one(). We do not need to worry about the counting for > 2M/1G sized pages. > > This patch disallows mapping of an ioreq server, when there's still > p2m_ioreq_server entry left, in case another mapping occurs right after > the current one being unmapped, releases its lock, with p2m table not > synced yet. > > This patch also disallows live migration, when there's remaining > p2m_ioreq_server entry in p2m table. The core reason is our current > implementation of p2m_change_entry_type_global() lacks information > to resync p2m_ioreq_server entries correctly if global_logdirty is > on. > > Signed-off-by: Yu Zhang <yu.c.zhang@xxxxxxxxxxxxxxx> > Reviewed-by: Paul Durrant <paul.durrant@xxxxxxxxxx> > --- > Cc: Paul Durrant <paul.durrant@xxxxxxxxxx> > Cc: Jan Beulich <jbeulich@xxxxxxxx> > Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx> > Cc: George Dunlap <george.dunlap@xxxxxxxxxxxxx> > Cc: Jun Nakajima <jun.nakajima@xxxxxxxxx> > Cc: Kevin Tian <kevin.tian@xxxxxxxxx> > > changes in v7: > - According to comments from George: add code to increase the > entry_count. > - Comment changes in {ept,p2m_pt}_set_entry. > > changes in v6: > - According to comments from Jan & George: move the count from > p2m_change_type_one() to {ept,p2m_pt}_set_entry. > - According to comments from George: comments change. > > changes in v5: > - According to comments from Jan: use unsigned long for entry_count; > - According to comments from Jan: refuse mapping requirement when > there's p2m_ioreq_server remained in p2m table. > - Added "Reviewed-by: Paul Durrant <paul.durrant@xxxxxxxxxx>" > > changes in v4: > - According to comments from Jan: use ASSERT() instead of 'if' > condition in p2m_change_type_one(). > - According to comments from Jan: commit message changes to mention > the p2m_ioreq_server are all based on 4K sized pages. > > changes in v3: > - Move the synchronously resetting logic into patch 5. > - According to comments from Jan: introduce p2m_check_changeable() > to clarify the p2m type change code. > - According to comments from George: use locks in the same order > to avoid deadlock, call p2m_change_entry_type_global() after unmap > of the ioreq server is finished. > > changes in v2: > - Move the calculation of ioreq server page entry_cout into > p2m_change_type_one() so that we do not need a seperate lock. > Note: entry_count is also calculated in resolve_misconfig()/ > do_recalc(), fortunately callers of both routines have p2m > lock protected already. > - Simplify logic in hvmop_set_mem_type(). > - Introduce routine p2m_finish_type_change() to walk the p2m > table and do the p2m reset. > --- > xen/arch/x86/hvm/ioreq.c | 8 ++++++++ > xen/arch/x86/mm/hap/hap.c | 9 +++++++++ > xen/arch/x86/mm/p2m-ept.c | 24 +++++++++++++++++++++++- > xen/arch/x86/mm/p2m-pt.c | 30 ++++++++++++++++++++++++++++-- > xen/arch/x86/mm/p2m.c | 9 +++++++++ > xen/include/asm-x86/p2m.h | 9 ++++++++- > 6 files changed, 85 insertions(+), 4 deletions(-) > > diff --git a/xen/arch/x86/hvm/ioreq.c b/xen/arch/x86/hvm/ioreq.c > index 5bf3b6d..07a6c26 100644 > --- a/xen/arch/x86/hvm/ioreq.c > +++ b/xen/arch/x86/hvm/ioreq.c > @@ -955,6 +955,14 @@ int hvm_map_mem_type_to_ioreq_server(struct domain *d, > ioservid_t id, > > spin_unlock_recursive(&d->arch.hvm_domain.ioreq_server.lock); > > + if ( rc == 0 && flags == 0 ) > + { > + struct p2m_domain *p2m = p2m_get_hostp2m(d); > + > + if ( read_atomic(&p2m->ioreq.entry_count) ) > + p2m_change_entry_type_global(d, p2m_ioreq_server, p2m_ram_rw); > + } > + > return rc; > } > > diff --git a/xen/arch/x86/mm/hap/hap.c b/xen/arch/x86/mm/hap/hap.c > index a57b385..4b591fe 100644 > --- a/xen/arch/x86/mm/hap/hap.c > +++ b/xen/arch/x86/mm/hap/hap.c > @@ -187,6 +187,15 @@ out: > */ > static int hap_enable_log_dirty(struct domain *d, bool_t log_global) > { > + struct p2m_domain *p2m = p2m_get_hostp2m(d); > + > + /* > + * Refuse to turn on global log-dirty mode if > + * there are outstanding p2m_ioreq_server pages. > + */ > + if ( log_global && read_atomic(&p2m->ioreq.entry_count) ) > + return -EBUSY; > + > /* turn on PG_log_dirty bit in paging mode */ > paging_lock(d); > d->arch.paging.mode |= PG_log_dirty; > diff --git a/xen/arch/x86/mm/p2m-ept.c b/xen/arch/x86/mm/p2m-ept.c > index cc1eb21..ecd5ceb 100644 > --- a/xen/arch/x86/mm/p2m-ept.c > +++ b/xen/arch/x86/mm/p2m-ept.c > @@ -544,6 +544,12 @@ static int resolve_misconfig(struct p2m_domain *p2m, > unsigned long gfn) > e.ipat = ipat; > if ( e.recalc && p2m_is_changeable(e.sa_p2mt) ) > { > + if ( e.sa_p2mt == p2m_ioreq_server ) > + { > + ASSERT(p2m->ioreq.entry_count > 0); > + p2m->ioreq.entry_count--; > + } > + > e.sa_p2mt = p2m_is_logdirty_range(p2m, gfn + i, gfn > + i) > ? p2m_ram_logdirty : p2m_ram_rw; > ept_p2m_type_to_flags(p2m, &e, e.sa_p2mt, e.access); > @@ -816,6 +822,22 @@ ept_set_entry(struct p2m_domain *p2m, unsigned long gfn, > mfn_t mfn, > new_entry.suppress_ve = is_epte_valid(&old_entry) ? > old_entry.suppress_ve : 1; > > + /* > + * p2m_ioreq_server is only used for 4K pages, so the > + * count shall only happen on ept page table entries. Actually, I liked the previous comment ("We only do x...") better. :-) FYI normally if you're trying to avoid saying "we" you use the passive voice, like this: "...so the count *is only done* on ept page table entries". But I don't think that's a big deal at this point: Reviewed-by: George Dunlap <george.dunlap@xxxxxxxxxx> _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx https://lists.xen.org/xen-devel
|
Lists.xenproject.org is hosted with RackSpace, monitoring our |