svn commit: r268660 - head/sys/amd64/amd64

[John Baldwin]

On Tuesday, July 15, 2014 9:52:20 am Ian Lepore wrote:
> On Tue, 2014-07-15 at 09:30 +0000, Konstantin Belousov wrote:
> > Author: kib
> > Date: Tue Jul 15 09:30:43 2014
> > New Revision: 268660
> > URL: http://svnweb.freebsd.org/changeset/base/268660
> > 
> > Log:
> >   Make amd64 pmap_copy_pages() functional for pages not mapped by DMAP.
> >   
> >   Requested and reviewed by:	royger
> >   Tested by:	pho, royger
> >   Sponsored by:	The FreeBSD Foundation
> >   MFC after:	1 week
> > 
> > Modified:
> >   head/sys/amd64/amd64/pmap.c
> > 
> > Modified: head/sys/amd64/amd64/pmap.c
> > 
==============================================================================
> > --- head/sys/amd64/amd64/pmap.c	Tue Jul 15 05:45:50 2014	(r268659)
> > +++ head/sys/amd64/amd64/pmap.c	Tue Jul 15 09:30:43 2014	(r268660)
> > @@ -390,6 +390,11 @@ SYSCTL_PROC(_vm_pmap, OID_AUTO, pcid_sav
> >      CTLFLAG_MPSAFE, NULL, 0, pmap_pcid_save_cnt_proc, "QU",
> >      "Count of saved TLB context on switch");
> >  
> > +/* pmap_copy_pages() over non-DMAP */
> > +static struct mtx cpage_lock;
> > +static vm_offset_t cpage_a;
> > +static vm_offset_t cpage_b;
> > +
> >  /*
> >   * Crashdump maps.
> >   */
> > @@ -1055,6 +1060,10 @@ pmap_init(void)
> >  	    M_WAITOK | M_ZERO);
> >  	for (i = 0; i < pv_npg; i++)
> >  		TAILQ_INIT(&pv_table[i].pv_list);
> > +
> > +	mtx_init(&cpage_lock, "cpage", NULL, MTX_DEF);
> > +	cpage_a = kva_alloc(PAGE_SIZE);
> > +	cpage_b = kva_alloc(PAGE_SIZE);
> >  }
> >  
> >  static SYSCTL_NODE(_vm_pmap, OID_AUTO, pde, CTLFLAG_RD, 0,
> > @@ -5064,19 +5073,58 @@ pmap_copy_pages(vm_page_t ma[], vm_offse
> >      vm_offset_t b_offset, int xfersize)
> >  {
> >  	void *a_cp, *b_cp;
> > +	vm_page_t m_a, m_b;
> > +	vm_paddr_t p_a, p_b;
> > +	pt_entry_t *pte;
> >  	vm_offset_t a_pg_offset, b_pg_offset;
> >  	int cnt;
> > +	boolean_t pinned;
> >  
> > +	pinned = FALSE;
> >  	while (xfersize > 0) {
> >  		a_pg_offset = a_offset & PAGE_MASK;
> > -		cnt = min(xfersize, PAGE_SIZE - a_pg_offset);
> > -		a_cp = (char *)PHYS_TO_DMAP(ma[a_offset >> PAGE_SHIFT]->
> > -		    phys_addr) + a_pg_offset;
> > +		m_a = ma[a_offset >> PAGE_SHIFT];
> > +		p_a = m_a->phys_addr;
> >  		b_pg_offset = b_offset & PAGE_MASK;
> > +		m_b = mb[b_offset >> PAGE_SHIFT];
> > +		p_b = m_b->phys_addr;
> > +		cnt = min(xfersize, PAGE_SIZE - a_pg_offset);
> >  		cnt = min(cnt, PAGE_SIZE - b_pg_offset);
> > -		b_cp = (char *)PHYS_TO_DMAP(mb[b_offset >> PAGE_SHIFT]->
> > -		    phys_addr) + b_pg_offset;
> > +		if (__predict_false(p_a < DMAP_MIN_ADDRESS ||
> > +		    p_a > DMAP_MIN_ADDRESS + dmaplimit)) {
> > +			mtx_lock(&cpage_lock);
> > +			sched_pin();
> > +			pinned = TRUE;
> > +			pte = vtopte(cpage_a);
> > +			*pte = p_a | X86_PG_A | X86_PG_V |
> > +			    pmap_cache_bits(kernel_pmap, m_a->md.pat_mode, 0);
> > +			invlpg(cpage_a);
> > +			a_cp = (char *)cpage_a + a_pg_offset;
> > +		} else {
> > +			a_cp = (char *)PHYS_TO_DMAP(p_a) + a_pg_offset;
> > +		}
> > +		if (__predict_false(p_b < DMAP_MIN_ADDRESS ||
> > +		    p_b > DMAP_MIN_ADDRESS + dmaplimit)) {
> > +			if (!pinned) {
> > +				mtx_lock(&cpage_lock);
> > +				sched_pin();
> > +				pinned = TRUE;
> > +			}
> > +			pte = vtopte(cpage_b);
> > +			*pte = p_b | X86_PG_A | X86_PG_M | X86_PG_RW |
> > +			    X86_PG_V | pmap_cache_bits(kernel_pmap,
> > +			    m_b->md.pat_mode, 0);
> > +			invlpg(cpage_b);
> > +			b_cp = (char *)cpage_b + b_pg_offset;
> > +		} else {
> > +			b_cp = (char *)PHYS_TO_DMAP(p_b) + b_pg_offset;
> > +		}
> >  		bcopy(a_cp, b_cp, cnt);
> > +		if (__predict_false(pinned)) {
> > +			sched_unpin();
> > +			mtx_unlock(&cpage_lock);
> > +			pinned = FALSE;
> 
> Should this pinned = FALSE be done under the cpage_lock to avoid a race?

It's a local variable, how would it race?  (No other thread/CPU should be able 
to "get" to it to either read or write to it, only curthread, so it shouldn't 
need any locking.)

-- 
John Baldwin