[src/trunk]: src/sys/arch/xen/x86 Make MP-safe: make sure the xpq_queue* are ...

[bouyer <bouyer%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/00a956a0bafb
branches:  trunk
changeset: 971861:00a956a0bafb
user:      bouyer <bouyer%NetBSD.org@localhost>
date:      Wed May 06 19:50:26 2020 +0000

description:
Make MP-safe: make sure the xpq_queue* are flushed before making the
pages visible to UVM.

diffstat:

 sys/arch/xen/x86/xen_bus_dma.c |  19 +++++++++++--------
 1 files changed, 11 insertions(+), 8 deletions(-)

diffs (55 lines):

diff -r 8f9bda88f3dd -r 00a956a0bafb sys/arch/xen/x86/xen_bus_dma.c
--- a/sys/arch/xen/x86/xen_bus_dma.c    Wed May 06 19:49:00 2020 +0000
+++ b/sys/arch/xen/x86/xen_bus_dma.c    Wed May 06 19:50:26 2020 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: xen_bus_dma.c,v 1.31 2020/04/25 15:26:17 bouyer Exp $  */
+/*     $NetBSD: xen_bus_dma.c,v 1.32 2020/05/06 19:50:26 bouyer Exp $  */
 /*     NetBSD bus_dma.c,v 1.21 2005/04/16 07:53:35 yamt Exp */
 
 /*-
@@ -32,7 +32,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: xen_bus_dma.c,v 1.31 2020/04/25 15:26:17 bouyer Exp $");
+__KERNEL_RCSID(0, "$NetBSD: xen_bus_dma.c,v 1.32 2020/05/06 19:50:26 bouyer Exp $");
 
 #include <sys/param.h>
 #include <sys/systm.h>
@@ -146,15 +146,18 @@
                pa = VM_PAGE_TO_PHYS(pg);
                xpmap_ptom_map(pa, ptoa(mfn+i));
                xpq_queue_machphys_update(((paddr_t)(mfn+i)) << PAGE_SHIFT, pa);
-               /* while here, give extra pages back to UVM */
+       }
+       /* Flush updates through and flush the TLB */
+       xpq_queue_tlb_flush();
+       splx(s);
+       /* now that ptom/mtop are valid, give the extra pages back to UVM */
+       for (pg = mlistp->tqh_first, i = 0; pg != NULL; pg = pgnext, i++) {
+               pgnext = pg->pageq.queue.tqe_next;
                if (i >= npagesreq) {
                        TAILQ_REMOVE(mlistp, pg, pageq.queue);
                        uvm_pagefree(pg);
                }
        }
-       /* Flush updates through and flush the TLB */
-       xpq_queue_tlb_flush();
-       splx(s);
        return 0;
 
 failed:
@@ -190,11 +193,11 @@
                pa = VM_PAGE_TO_PHYS(pg);
                xpmap_ptom_map(pa, ptoa(mfn));
                xpq_queue_machphys_update(((paddr_t)mfn) << PAGE_SHIFT, pa);
+               /* slow but we don't care */
+               xpq_queue_tlb_flush();
                TAILQ_REMOVE(mlistp, pg, pageq.queue);
                uvm_pagefree(pg);
        }
-       /* Flush updates through and flush the TLB */
-       xpq_queue_tlb_flush();
        splx(s);
        return error;
 }