From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoph Egger Subject: Re: Re: [PATCH 1 of 4] Nested p2m: implement "flush" as a first-class action Date: Thu, 23 Jun 2011 17:21:21 +0200 Message-ID: <4E0359F1.1060702@amd.com> References: <4E03368F.7000504@amd.com> <4E0337F8.3020908@amd.com> <4E0355E2.5060306@amd.com> Mime-Version: 1.0 Content-Type: text/plain; charset="ISO-8859-1"; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <4E0355E2.5060306@amd.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: Tim Deegan , "xen-devel@lists.xensource.com" List-Id: xen-devel@lists.xenproject.org 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(). Christoph 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:[] 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) [] p2m_flush_locked+0x1a8/0x2be >>> (XEN) [] p2m_flush_nestedp2m+0xea/0x140 >>> (XEN) [] hap_write_p2m_entry+0x223/0x246 >>> (XEN) [] paging_write_p2m_entry+0x6e/0x75 >>> (XEN) [] p2m_set_entry+0x42b/0x6a8 >>> (XEN) [] set_p2m_entry+0xf2/0x140 >>> (XEN) [] p2m_remove_page+0x1dd/0x1ec >>> (XEN) [] guest_physmap_remove_page+0x109/0x148 >>> (XEN) [] arch_memory_op+0x6af/0x1039 >>> (XEN) [] do_memory_op+0x1bd7/0x1c2c >>> (XEN) [] syscall_enter+0xc8/0x122 >>> (XEN) >>> (XEN) >>> (XEN) **************************************** >>> >>> Christoph >>> >>> >>> >>> On 06/22/11 18:10, Tim Deegan wrote: >>>> # HG changeset patch >>>> # User Tim Deegan >>>> # 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 >>>> >>>> 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); >>>> >>>> -- ---to satisfy European Law for business letters: Advanced Micro Devices GmbH Einsteinring 24, 85689 Dornach b. 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