Attachment 146536 Details for Bug 224227 – [XEN] Stricter TLB-flush discipline when unshadowing pagetables

[patch] [XEN] Stricter TLB-flush discipline when unshadowing pagetables

p (text/plain), 4.81 KB, created by Herbert Xu on 2007-01-25 13:32:28 UTC

(hide)

Description:

Filename:

MIME Type:

Creator: Herbert Xu

Created: 2007-01-25 13:32:28 UTC

Size: 4.81 KB

patch

obsolete

>diff -ur xen.orig/arch/x86/mm/shadow/common.c xen/arch/x86/mm/shadow/common.c
>--- xen.orig/arch/x86/mm/shadow/common.c	2007-01-25 22:24:46.000000000 +1100
>+++ xen/arch/x86/mm/shadow/common.c	2007-01-25 22:19:15.000000000 +1100
>@@ -573,13 +573,18 @@
> {
>     /* Need a vpcu for calling unpins; for now, since we don't have
>      * per-vcpu shadows, any will do */
>-    struct vcpu *v = d->vcpu[0];
>+    struct vcpu *v, *v2;
>     struct list_head *l, *t;
>     struct page_info *pg;
>+    cpumask_t flushmask = CPU_MASK_NONE;
>     mfn_t smfn;
> 
>     if ( chunk_is_available(d, order) ) return; 
>     
>+    v = current;
>+    if ( v->domain != d )
>+        v = d->vcpu[0];
>+
>     /* Stage one: walk the list of top-level pages, unpinning them */
>     perfc_incrc(shadow_prealloc_1);
>     list_for_each_backwards_safe(l, t, &d->arch.shadow.toplevel_shadows)
>@@ -608,24 +613,26 @@
>      * loaded in cr3 on some vcpu.  Walk them, unhooking the non-Xen
>      * mappings. */
>     perfc_incrc(shadow_prealloc_2);
>-    v = current;
>-    if ( v->domain != d )
>-        v = d->vcpu[0];
>-    /* Walk the list from the tail: recently used toplevels have been pulled
>-     * to the head */
>     list_for_each_backwards_safe(l, t, &d->arch.shadow.toplevel_shadows)
>     {
>         pg = list_entry(l, struct page_info, list);
>         smfn = page_to_mfn(pg);
>         shadow_unhook_mappings(v, smfn);
> 
>-        /* Need to flush TLB if we've altered our own tables */
>-        if ( !shadow_mode_external(d) 
>-             && pagetable_get_pfn(current->arch.shadow_table) == mfn_x(smfn) )
>-            local_flush_tlb();
>-        
>+        /* Remember to flush TLBs: we have removed shadow entries that 
>+         * were in use by some vcpu(s). */
>+        for_each_vcpu(d, v2) 
>+        {
>+            if ( pagetable_get_pfn(v2->arch.shadow_table) == mfn_x(smfn) )
>+                cpus_or(flushmask, v2->vcpu_dirty_cpumask, flushmask);
>+        }
>+
>         /* See if that freed up a chunk of appropriate size */
>-        if ( chunk_is_available(d, order) ) return;
>+        if ( chunk_is_available(d, order) ) 
>+        {
>+            flush_tlb_mask(flushmask);
>+            return;
>+        }
>     }
>     
>     /* Nothing more we can do: all remaining shadows are of pages that
>@@ -2201,6 +2208,10 @@
>                       mfn_x(gmfn), pg->shadow_flags);
>         domain_crash(v->domain);
>     }
>+
>+    /* Need to flush TLBs now, so that linear maps are safe next time we 
>+     * take a fault. */
>+    flush_tlb_mask(v->domain->domain_dirty_cpumask);
> }
> 
> void
>diff -ur xen.orig/arch/x86/mm/shadow/multi.c xen/arch/x86/mm/shadow/multi.c
>--- xen.orig/arch/x86/mm/shadow/multi.c	2007-01-04 17:21:27.000000000 +1100
>+++ xen/arch/x86/mm/shadow/multi.c	2007-01-25 22:16:44.000000000 +1100
>@@ -2821,35 +2821,10 @@
>          sh_mfn_is_a_page_table(gmfn) )
>     {
>         u32 flags = mfn_to_page(gmfn)->shadow_flags;
>-        mfn_t smfn;
>         if ( !(flags & (SHF_L2_32|SHF_L3_PAE|SHF_L4_64)) )
>         {
>             perfc_incrc(shadow_early_unshadow);
>             sh_remove_shadows(v, gmfn, 0 /* Can fail to unshadow */ );
>-            return;
>-        }
>-        /* SHF_unhooked_mappings is set to make sure we only unhook
>-         * once in a single batch of updates. It is reset when this
>-         * top-level page is loaded into CR3 again */
>-        if ( !(flags & SHF_unhooked_mappings) ) 
>-        {
>-            perfc_incrc(shadow_early_unshadow_top);
>-            mfn_to_page(gmfn)->shadow_flags |= SHF_unhooked_mappings;
>-            if ( flags & SHF_L2_32 )
>-            {
>-                smfn = get_shadow_status(v, gmfn, PGC_SH_l2_32_shadow);
>-                shadow_unhook_mappings(v, smfn);
>-            }
>-            if ( flags & SHF_L3_PAE ) 
>-            {
>-                smfn = get_shadow_status(v, gmfn, PGC_SH_l3_pae_shadow);
>-                shadow_unhook_mappings(v, smfn);
>-            }
>-            if ( flags & SHF_L4_64 ) 
>-            {
>-                smfn = get_shadow_status(v, gmfn, PGC_SH_l4_64_shadow);
>-                shadow_unhook_mappings(v, smfn);
>-            }
>         }
>     }
>     v->arch.shadow.last_emulated_mfn = mfn_x(gmfn);
>diff -ur xen.orig/include/asm-x86/perfc_defn.h xen/include/asm-x86/perfc_defn.h
>--- xen.orig/include/asm-x86/perfc_defn.h	2007-01-04 17:21:29.000000000 +1100
>+++ xen/include/asm-x86/perfc_defn.h	2007-01-25 22:15:55.000000000 +1100
>@@ -75,7 +75,6 @@
> PERFCOUNTER_CPU(shadow_mappings,       "shadow removes all mappings")
> PERFCOUNTER_CPU(shadow_mappings_bf,    "shadow rm-mappings brute-force")
> PERFCOUNTER_CPU(shadow_early_unshadow, "shadow unshadows for fork/exit")
>-PERFCOUNTER_CPU(shadow_early_unshadow_top, "shadow unhooks for fork/exit")
> PERFCOUNTER_CPU(shadow_unshadow,       "shadow unshadows a page")
> PERFCOUNTER_CPU(shadow_up_pointer,     "shadow unshadow by up-pointer")
> PERFCOUNTER_CPU(shadow_unshadow_bf,    "shadow unshadow brute-force")

Actions: View | Diff

Attachments on bug 224227: 146536