At 17:21 +0200 on 23 Jun (1308849681), Christoph Egger wrote:
>
> Now I see a significant slowdown of the L2 guest with multiple vcpus.
> The reason is I see 10 times more IPIs for each vcpu with
> p2m_flush_nestedp2m().
>
> Please add back nestedhvm_vmcx_flushtlbdomain().
It wasn't safe. You need to kick other CPUs off the p2m table before
you free its memory. But I'll look into avoiding those IPIs.
Tim.
> On 06/23/11 17:04, Christoph Egger wrote:
> >
> >I have a fix for this crash. See inline.
> >
> >Christoph
> >
> >
> >On 06/23/11 14:56, Christoph Egger wrote:
> >>On 06/23/11 14:50, Christoph Egger wrote:
> >>>
> >>>This patch crashes the host (and it doesn't disappear with the other
> >>>patches applied):
> >>
> >>err.. it crashes the host when the l1 guest boots the hvmloader invokes
> >>the VGA BIOS.
> >>
> >>>(XEN) Assertion 'pfn_to_pdx(ma>> PAGE_SHIFT)< (DIRECTMAP_SIZE>>
> >>>PAGE_SHIFT)'
> >>>failed at xen/include/asm/x86_64/page.h:99
> >>>(XEN) ----[ Xen-4.2-unstable x86_64 debug=y Tainted: C ]----
> >>>(XEN) CPU: 1
> >>>(XEN) RIP: e008:[<ffff82c4801d2007>] p2m_flush_locked+0x1a8/0x2be
> >>>(XEN) RFLAGS: 0000000000010212 CONTEXT: hypervisor
> >>>(XEN) rax: 0000000000000000 rbx: ffff830421db1d90 rcx: 0000000000000000
> >>>(XEN) rdx: f82f608076a60000 rsi: 000f82f608076a60 rdi: 0000000000000000
> >>>(XEN) rbp: ffff830425217a08 rsp: ffff8304252179c8 r8: 0000000000000000
> >>>(XEN) r9: 0000000000000004 r10: 00000000fffffffb r11: 0000000000000003
> >>>(XEN) r12: ffff830421db1d90 r13: ffff82f608076a60 r14: ffff830403bbebe8
> >>>(XEN) r15: ffff830403bbe000 cr0: 000000008005003b cr4: 00000000000406f0
> >>>(XEN) cr3: 0000000420f2b000 cr2: 000000000045f000
> >>>(XEN) ds: 0017 es: 0017 fs: 0000 gs: 0000 ss: e010 cs: e008
> >>>(XEN) Xen stack trace from rsp=ffff8304252179c8:
> >>>(XEN) ffff830403bbebe8 ffff830421db1d90 ffff830421db1d90
> >>>0000000000000000
> >>>(XEN) ffff830403bbe000 ffff830403bbebe8 ffff830403bbebe8
> >>>ffff830403bbeab0
> >>>(XEN) ffff830425217a38 ffff82c4801d2599 0000000000000001
> >>>0000000000000067
> >>>(XEN) ffff830403bbeab0 ffff830403af4000 ffff830425217a88
> >>>ffff82c480208a8c
> >>>(XEN) 0000000125941810 ffff830403bbe000 0000000000000000
> >>>ffff830425217b18
> >>>(XEN) ffff830421db1cc0 00000000000ff000 ffffffffffffffff
> >>>0000000000000000
> >>>(XEN) ffff830425217a98 ffff82c4801ce585 ffff830425217b68
> >>>ffff82c4801d4b4e
> >>>(XEN) 0000000000000200 1000000000000000 ffff830425217b28
> >>>ffff830425217b20
> >>>(XEN) 0000000000000001 ffff830425217ae8 ffff830425217ef8
> >>>ffff830403af4000
> >>>(XEN) 0000000000000000 0000000000000000 0000000000000000
> >>>0000000000000000
> >>>(XEN) 0000000000000000 0000000000000000 0000000000000000
> >>>ffff830403af4000
> >>>(XEN) 0000000000403af4 ffff82c4801d5ec1 ffff830425217bfc
> >>>ffffffffffffffff
> >>>(XEN) 0000000000000000 0000000000000001 00000000000ff000
> >>>ffff830421db1cc0
> >>>(XEN) ffff830425217bb8 ffff82c4801d02d1 0000000100000007
> >>>ffff830403bbe000
> >>>(XEN) 0000000125217bc8 ffff8280019fafc0 ffff82c400cfd7e0
> >>>000000000033f5f8
> >>>(XEN) ffff830421db1cc0 0000000000000001 ffff830425217c28
> >>>ffff82c4801d053d
> >>>(XEN) ffff830425217bfc ffff830425217bf8 0000000025217bf0
> >>>00000000000ff000
> >>>(XEN) 0000000000000001 ffff830425217c10 0000000000000007
> >>>ffff830421db1cc0
> >>>(XEN) ffff830421db1cc0 ffff830425217f18 ffff82c4802e1260
> >>>0000000000000000
> >>>(XEN) ffff830425217c78 ffff82c4801d11fa 000000000033f5f7
> >>>00000000000ff000
> >>>(XEN) Xen call trace:
> >>>(XEN) [<ffff82c4801d2007>] p2m_flush_locked+0x1a8/0x2be
> >>>(XEN) [<ffff82c4801d2599>] p2m_flush_nestedp2m+0xea/0x140
> >>>(XEN) [<ffff82c480208a8c>] hap_write_p2m_entry+0x223/0x246
> >>>(XEN) [<ffff82c4801ce585>] paging_write_p2m_entry+0x6e/0x75
> >>>(XEN) [<ffff82c4801d4b4e>] p2m_set_entry+0x42b/0x6a8
> >>>(XEN) [<ffff82c4801d02d1>] set_p2m_entry+0xf2/0x140
> >>>(XEN) [<ffff82c4801d053d>] p2m_remove_page+0x1dd/0x1ec
> >>>(XEN) [<ffff82c4801d11fa>] guest_physmap_remove_page+0x109/0x148
> >>>(XEN) [<ffff82c480168000>] arch_memory_op+0x6af/0x1039
> >>>(XEN) [<ffff82c4801134fb>] do_memory_op+0x1bd7/0x1c2c
> >>>(XEN) [<ffff82c480217708>] syscall_enter+0xc8/0x122
> >>>(XEN)
> >>>(XEN)
> >>>(XEN) ****************************************
> >>>
> >>>Christoph
> >>>
> >>>
> >>>
> >>>On 06/22/11 18:10, Tim Deegan wrote:
> >>>># HG changeset patch
> >>>># User Tim Deegan<Tim.Deegan@xxxxxxxxxx>
> >>>># Date 1308758648 -3600
> >>>># Node ID c323e69a0a08ce9f1e54d2e2fa2edd9845bc8efe
> >>>># Parent b7e5a25663329254cba539e21f4fbd5b32c67556
> >>>>Nested p2m: implement "flush" as a first-class action
> >>>>rather than using the teardown and init functions.
> >>>>This makes the locking clearer and avoids an expensive scan of all
> >>>>pfns that's only needed for non-nested p2ms. It also moves the
> >>>>tlb flush into the proper place in the flush logic, avoiding a
> >>>>possible race against other CPUs.
> >>>>
> >>>>Signed-off-by: Tim Deegan<Tim.Deegan@xxxxxxxxxx>
> >>>>
> >>>>diff -r b7e5a2566332 -r c323e69a0a08 xen/arch/x86/hvm/nestedhvm.c
> >>>>--- a/xen/arch/x86/hvm/nestedhvm.c Tue Jun 21 18:28:53 2011 +0100
> >>>>+++ b/xen/arch/x86/hvm/nestedhvm.c Wed Jun 22 17:04:08 2011 +0100
> >>>>@@ -119,12 +119,6 @@ nestedhvm_vmcx_flushtlb(struct p2m_domai
> >>>> cpus_clear(p2m->p2m_dirty_cpumask);
> >>>> }
> >>>>
> >>>>-void
> >>>>-nestedhvm_vmcx_flushtlbdomain(struct domain *d)
> >>>>-{
> >>>>- on_selected_cpus(d->domain_dirty_cpumask, nestedhvm_flushtlb_ipi, d,
> >>>>1);
> >>>>-}
> >>>>-
> >>>> bool_t
> >>>> nestedhvm_is_n2(struct vcpu *v)
> >>>> {
> >>>>diff -r b7e5a2566332 -r c323e69a0a08 xen/arch/x86/mm/p2m.c
> >>>>--- a/xen/arch/x86/mm/p2m.c Tue Jun 21 18:28:53 2011 +0100
> >>>>+++ b/xen/arch/x86/mm/p2m.c Wed Jun 22 17:04:08 2011 +0100
> >>>>@@ -1050,20 +1050,41 @@ p2m_getlru_nestedp2m(struct domain *d, s
> >>>> return lrup2m;
> >>>> }
> >>>>
> >>>>-static int
> >>>>+/* Reset this p2m table to be empty */
> >>>>+static void
> >>>> p2m_flush_locked(struct p2m_domain *p2m)
> >>>> {
> >>>>- ASSERT(p2m);
> >>>>- if (p2m->cr3 == CR3_EADDR)
> >>>>- /* Microoptimisation: p2m is already empty.
> >>>>- * => about 0.3% speedup of overall system performance.
> >>>>- */
> >>>>- return 0;
> >>>>+ struct page_info *top, *pg;
> >>>>+ struct domain *d = p2m->domain;
> >>>>+ void *p;
> >+ mfn_t top_mfn;
> >
> >>>>
> >>>>- p2m_teardown(p2m);
> >>>>- p2m_initialise(p2m->domain, p2m);
> >>>>- p2m->write_p2m_entry = nestedp2m_write_p2m_entry;
> >>>>- return p2m_alloc_table(p2m);
> >>>>+ p2m_lock(p2m);
> >>>>+
> >>>>+ /* "Host" p2m tables can have shared entries&c that need a bit more
> >>>>+ * care when discarding them */
> >>>>+ ASSERT(p2m_is_nestedp2m(p2m));
> >>>>+ ASSERT(page_list_empty(&p2m->pod.super));
> >>>>+ ASSERT(page_list_empty(&p2m->pod.single));
> >>>>+
> >>>>+ /* This is no longer a valid nested p2m for any address space */
> >>>>+ p2m->cr3 = CR3_EADDR;
> >>>>+
> >>>>+ /* Zap the top level of the trie */
> >
> >+ top_mfn = pagetable_get_mfn(p2m_get_pagetable(p2m));
> >+ top = mfn_to_page(top_mfn);
> >+ p = map_domain_page(mfn_x(top_mfn));
> >
> >>>>+ clear_page(p);
> >>>>+ unmap_domain_page(p);
> >>>>+
> >>>>+ /* Make sure nobody else is using this p2m table */
> >>>>+ nestedhvm_vmcx_flushtlb(p2m);
> >>>>+
> >>>>+ /* Free the rest of the trie pages back to the paging pool */
> >>>>+ while ( (pg = page_list_remove_head(&p2m->pages)) )
> >>>>+ if ( pg != top )
> >>>>+ d->arch.paging.free_page(d, pg);
> >>>>+ page_list_add(top,&p2m->pages);
> >>>>+
> >>>>+ p2m_unlock(p2m);
> >>>> }
> >>>>
> >>>> void
> >>>>@@ -1074,9 +1095,8 @@ p2m_flush(struct vcpu *v, struct p2m_dom
> >>>> ASSERT(v->domain == d);
> >>>> vcpu_nestedhvm(v).nv_p2m = NULL;
> >>>> nestedp2m_lock(d);
> >>>>- BUG_ON(p2m_flush_locked(p2m) != 0);
> >>>>+ p2m_flush_locked(p2m);
> >>>> hvm_asid_flush_vcpu(v);
> >>>>- nestedhvm_vmcx_flushtlb(p2m);
> >>>> nestedp2m_unlock(d);
> >>>> }
> >>>>
> >>>>@@ -1086,12 +1106,8 @@ p2m_flush_nestedp2m(struct domain *d)
> >>>> int i;
> >>>>
> >>>> nestedp2m_lock(d);
> >>>>- for (i = 0; i< MAX_NESTEDP2M; i++) {
> >>>>- struct p2m_domain *p2m = d->arch.nested_p2m[i];
> >>>>- BUG_ON(p2m_flush_locked(p2m) != 0);
> >>>>- cpus_clear(p2m->p2m_dirty_cpumask);
> >>>>- }
> >>>>- nestedhvm_vmcx_flushtlbdomain(d);
> >>>>+ for ( i = 0; i< MAX_NESTEDP2M; i++ )
> >>>>+ p2m_flush_locked(d->arch.nested_p2m[i]);
> >>>> nestedp2m_unlock(d);
> >>>> }
> >>>>
> >>>>@@ -1104,7 +1120,7 @@ p2m_get_nestedp2m(struct vcpu *v, uint64
> >>>> volatile struct nestedvcpu *nv =&vcpu_nestedhvm(v);
> >>>> struct domain *d;
> >>>> struct p2m_domain *p2m;
> >>>>- int i, rv;
> >>>>+ int i;
> >>>>
> >>>> if (cr3 == 0 || cr3 == CR3_EADDR)
> >>>> cr3 = v->arch.hvm_vcpu.guest_cr[3];
> >>>>@@ -1136,9 +1152,7 @@ p2m_get_nestedp2m(struct vcpu *v, uint64
> >>>> */
> >>>> for (i = 0; i< MAX_NESTEDP2M; i++) {
> >>>> p2m = p2m_getlru_nestedp2m(d, NULL);
> >>>>- rv = p2m_flush_locked(p2m);
> >>>>- if (rv == 0)
> >>>>- break;
> >>>>+ p2m_flush_locked(p2m);
> >>>> }
> >>>> nv->nv_p2m = p2m;
> >>>> p2m->cr3 = cr3;
> >>>>diff -r b7e5a2566332 -r c323e69a0a08 xen/include/asm-x86/hvm/nestedhvm.h
> >>>>--- a/xen/include/asm-x86/hvm/nestedhvm.h Tue Jun 21 18:28:53 2011
> >>>>+0100
> >>>>+++ b/xen/include/asm-x86/hvm/nestedhvm.h Wed Jun 22 17:04:08 2011
> >>>>+0100
> >>>>@@ -61,7 +61,6 @@ unsigned long *nestedhvm_vcpu_iomap_get(
> >>>> (!!vcpu_nestedhvm((v)).nv_vmswitch_in_progress)
> >>>>
> >>>> void nestedhvm_vmcx_flushtlb(struct p2m_domain *p2m);
> >>>>-void nestedhvm_vmcx_flushtlbdomain(struct domain *d);
> >>>>
> >>>> bool_t nestedhvm_is_n2(struct vcpu *v);
> >>>>
> >>>>
>
>
> --
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>
>
> _______________________________________________
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--
Tim Deegan <Tim.Deegan@xxxxxxxxxx>
Principal Software Engineer, Xen Platform Team
Citrix Systems UK Ltd. (Company #02937203, SL9 0BG)
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