From: Christian Borntraeger <borntraeger@de.ibm.com> To: David Hildenbrand <david@redhat.com>, Janosch Frank <frankja@linux.vnet.ibm.com> Cc: KVM <kvm@vger.kernel.org>, Cornelia Huck <cohuck@redhat.com>, Thomas Huth <thuth@redhat.com>, Ulrich Weigand <Ulrich.Weigand@de.ibm.com>, Claudio Imbrenda <imbrenda@linux.ibm.com>, linux-s390 <linux-s390@vger.kernel.org>, Michael Mueller <mimu@linux.ibm.com>, Vasily Gorbik <gor@linux.ibm.com> Subject: Re: [PATCH v2 02/42] KVM: s390/interrupt: do not pin adapter interrupt pages Date: Thu, 20 Feb 2020 14:31:30 +0100 Message-ID: <45954200-ccfe-cfac-200d-d1b903d9fc39@de.ibm.com> (raw) In-Reply-To: <073d3666-480e-5ba5-a46b-4cbd615f4174@redhat.com> On 17.02.20 10:43, David Hildenbrand wrote: > On 14.02.20 23:26, Christian Borntraeger wrote: >> From: Ulrich Weigand <Ulrich.Weigand@de.ibm.com> >> >> The adapter interrupt page containing the indicator bits is currently >> pinned. That means that a guest with many devices can pin a lot of >> memory pages in the host. This also complicates the reference tracking >> which is needed for memory management handling of protected virtual >> machines. It might also have some strange side effects for madvise >> MADV_DONTNEED and other things. >> >> We can simply try to get the userspace page set the bits and free the >> page. By storing the userspace address in the irq routing entry instead >> of the guest address we can actually avoid many lookups and list walks >> so that this variant is very likely not slower. >> >> If userspace messes around with the memory slots the worst thing that >> can happen is that we write to some other memory within that process. >> As we get the the page with FOLL_WRITE this can also not be used to >> write to shared read-only pages. >> >> Signed-off-by: Ulrich Weigand <Ulrich.Weigand@de.ibm.com> >> [borntraeger@de.ibm.com: patch simplification] >> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com> >> --- >> Documentation/virt/kvm/devices/s390_flic.rst | 11 +- >> arch/s390/include/asm/kvm_host.h | 3 - >> arch/s390/kvm/interrupt.c | 170 ++++++------------- >> 3 files changed, 53 insertions(+), 131 deletions(-) >> >> diff --git a/Documentation/virt/kvm/devices/s390_flic.rst b/Documentation/virt/kvm/devices/s390_flic.rst >> index 954190da7d04..ea96559ba501 100644 >> --- a/Documentation/virt/kvm/devices/s390_flic.rst >> +++ b/Documentation/virt/kvm/devices/s390_flic.rst >> @@ -108,16 +108,9 @@ Groups: >> mask or unmask the adapter, as specified in mask >> >> KVM_S390_IO_ADAPTER_MAP >> - perform a gmap translation for the guest address provided in addr, >> - pin a userspace page for the translated address and add it to the >> - list of mappings >> - >> - .. note:: A new mapping will be created unconditionally; therefore, >> - the calling code should avoid making duplicate mappings. >> - >> + This is now a no-op. The mapping is purely done by the irq route. >> KVM_S390_IO_ADAPTER_UNMAP >> - release a userspace page for the translated address specified in addr >> - from the list of mappings >> + This is now a no-op. The mapping is purely done by the irq route. >> > > The interface should have accepted a hva from the very start and not > guest addresses ... right, but that is history. > > [...] >> + /* >> + * We resolve the gpa to hva when setting the IRQ routing. the set_irq >> + * code uses get_user_pages_remote to do the actual write. > > nit: "get_user_pages_remote()" ack. > >> + */ >> case KVM_S390_IO_ADAPTER_MAP: >> - ret = kvm_s390_adapter_map(dev->kvm, req.id, req.addr); >> - break; >> case KVM_S390_IO_ADAPTER_UNMAP: >> - ret = kvm_s390_adapter_unmap(dev->kvm, req.id, req.addr); >> - break; >> + return 0; >> default: >> ret = -EINVAL; >> } >> @@ -2699,19 +2622,21 @@ static unsigned long get_ind_bit(__u64 addr, unsigned long bit_nr, bool swap) >> return swap ? (bit ^ (BITS_PER_LONG - 1)) : bit; >> } >> >> -static struct s390_map_info *get_map_info(struct s390_io_adapter *adapter, >> - u64 addr) >> +static struct page *get_map_page(struct kvm *kvm, >> + struct s390_io_adapter *adapter, >> + u64 uaddr) >> { >> - struct s390_map_info *map; >> + struct page *page = NULL; >> >> if (!adapter) >> return NULL; > > AFAIKs, this check is not necessary. Right otherwise we would crash earlier. > >> - >> - list_for_each_entry(map, &adapter->maps, list) { >> - if (map->guest_addr == addr) >> - return map; >> - } >> - return NULL; >> + if (!uaddr) >> + return NULL; > > I do wonder if that check is necessary. I don't think so but might be > missing something. Nothing should break when we remove this check. get_user_pages_remote will also return NULL (as newer kernels usually forbid mapping things at 0). Will remove. [...] >> @@ -2818,23 +2746,27 @@ int kvm_set_routing_entry(struct kvm *kvm, >> struct kvm_kernel_irq_routing_entry *e, >> const struct kvm_irq_routing_entry *ue) >> { >> - int ret; >> + u64 uaddr; >> >> switch (ue->type) { >> + /* we store the userspace addresses instead of the guest addresses */ >> case KVM_IRQ_ROUTING_S390_ADAPTER: >> e->set = set_adapter_int; >> - e->adapter.summary_addr = ue->u.adapter.summary_addr; >> - e->adapter.ind_addr = ue->u.adapter.ind_addr; >> + uaddr = gmap_translate(kvm->arch.gmap, ue->u.adapter.summary_addr); >> + if (uaddr == -EFAULT) >> + return -EFAULT; >> + e->adapter.summary_addr = uaddr; >> + uaddr = gmap_translate(kvm->arch.gmap, ue->u.adapter.ind_addr); >> + if (uaddr == -EFAULT) >> + return -EFAULT; > > AFAIK, leaving e->adapter.summary_addr set is not an issue. > > Interesting, in kvm_s390_adapter_map(), we didn't synchronize again slot > updates when doing the gmap_translate(), which looks wrong to me ... > > It seems to be the same thing here. I do wonder if it is safe to do a > gmap_translate() here, looks like this can race with > kvm_arch_commit_memory_region(). > > I would have assumed we need e.g., the slots_lock while doing the > gmap_translate() - or a srcu_read_lock(&vcpu->kvm->srcu) or similar ... gmap_translate does this via the gmap and it holds the mm sem. gmap_unmap_segment takes the same lock. So I think we are ok here. > > Apart from that, looks good to me. >
next prev parent reply index Thread overview: 132+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-02-14 22:26 [PATCH v2 00/42] KVM: s390: Add support for protected VMs Christian Borntraeger 2020-02-14 22:26 ` [PATCH v2 01/42] mm:gup/writeback: add callbacks for inaccessible pages Christian Borntraeger 2020-02-17 9:14 ` David Hildenbrand 2020-02-17 11:10 ` Christian Borntraeger 2020-02-18 8:27 ` David Hildenbrand 2020-02-18 15:46 ` Sean Christopherson 2020-02-18 16:02 ` Will Deacon 2020-02-18 16:15 ` Christian Borntraeger 2020-02-18 21:35 ` Sean Christopherson 2020-02-19 8:31 ` David Hildenbrand 2020-02-14 22:26 ` [PATCH v2 02/42] KVM: s390/interrupt: do not pin adapter interrupt pages Christian Borntraeger 2020-02-17 9:43 ` David Hildenbrand 2020-02-20 12:18 ` David Hildenbrand 2020-02-20 13:31 ` Christian Borntraeger [this message] 2020-02-20 13:34 ` David Hildenbrand 2020-02-14 22:26 ` [PATCH v2 03/42] s390/protvirt: introduce host side setup Christian Borntraeger 2020-02-17 9:53 ` David Hildenbrand 2020-02-17 11:11 ` Christian Borntraeger 2020-02-17 11:13 ` David Hildenbrand 2020-02-14 22:26 ` [PATCH v2 04/42] s390/protvirt: add ultravisor initialization Christian Borntraeger 2020-02-17 9:57 ` David Hildenbrand 2020-02-17 11:13 ` Christian Borntraeger 2020-02-14 22:26 ` [PATCH v2 05/42] s390/mm: provide memory management functions for protected KVM guests Christian Borntraeger 2020-02-17 10:21 ` David Hildenbrand 2020-02-17 11:28 ` Christian Borntraeger 2020-02-17 12:07 ` David Hildenbrand 2020-02-14 22:26 ` [PATCH v2 06/42] s390/mm: add (non)secure page access exceptions handlers Christian Borntraeger 2020-02-14 22:26 ` [PATCH v2 07/42] KVM: s390: protvirt: Add UV debug trace Christian Borntraeger 2020-02-17 10:41 ` David Hildenbrand 2020-02-14 22:26 ` [PATCH v2 08/42] KVM: s390: add new variants of UV CALL Christian Borntraeger 2020-02-17 10:42 ` David Hildenbrand 2020-02-14 22:26 ` [PATCH v2 09/42] KVM: s390: protvirt: Add initial vm and cpu lifecycle handling Christian Borntraeger 2020-02-17 10:56 ` David Hildenbrand 2020-02-17 12:04 ` Christian Borntraeger 2020-02-17 12:09 ` David Hildenbrand 2020-02-17 14:53 ` [PATCH 0/2] example changes Christian Borntraeger 2020-02-17 14:53 ` [PATCH 1/2] lock changes Christian Borntraeger 2020-02-17 14:53 ` [PATCH 2/2] merge vm/cpu create Christian Borntraeger 2020-02-17 15:00 ` Janosch Frank 2020-02-17 15:02 ` Christian Borntraeger 2020-02-19 11:02 ` Christian Borntraeger 2020-02-17 19:18 ` [PATCH 0/2] example changes David Hildenbrand 2020-02-18 8:09 ` [PATCH v2 09/42] KVM: s390: protvirt: Add initial vm and cpu lifecycle handling Christian Borntraeger 2020-02-18 8:39 ` [PATCH v2.1] " Christian Borntraeger 2020-02-18 9:12 ` David Hildenbrand 2020-02-18 21:18 ` Christian Borntraeger 2020-02-19 8:32 ` David Hildenbrand 2020-02-19 11:01 ` Christian Borntraeger 2020-02-18 9:56 ` David Hildenbrand 2020-02-18 20:26 ` Christian Borntraeger 2020-02-14 22:26 ` [PATCH v2 10/42] KVM: s390: protvirt: Add KVM api documentation Christian Borntraeger 2020-02-14 22:26 ` [PATCH v2 11/42] KVM: s390: protvirt: Secure memory is not mergeable Christian Borntraeger 2020-02-14 22:26 ` [PATCH v2 12/42] KVM: s390/mm: Make pages accessible before destroying the guest Christian Borntraeger 2020-02-14 22:26 ` [PATCH v2 13/42] KVM: s390: protvirt: Handle SE notification interceptions Christian Borntraeger 2020-02-14 22:26 ` [PATCH v2 14/42] KVM: s390: protvirt: Instruction emulation Christian Borntraeger 2020-02-14 22:26 ` [PATCH v2 15/42] KVM: s390: protvirt: Add interruption injection controls Christian Borntraeger 2020-02-17 10:59 ` David Hildenbrand 2020-02-14 22:26 ` [PATCH v2 16/42] KVM: s390: protvirt: Implement interruption injection Christian Borntraeger 2020-02-14 22:26 ` [PATCH v2 17/42] KVM: s390: protvirt: Add SCLP interrupt handling Christian Borntraeger 2020-02-14 22:26 ` [PATCH v2 18/42] KVM: s390: protvirt: Handle spec exception loops Christian Borntraeger 2020-02-14 22:26 ` [PATCH v2 19/42] KVM: s390: protvirt: Add new gprs location handling Christian Borntraeger 2020-02-17 11:01 ` David Hildenbrand 2020-02-17 11:33 ` Christian Borntraeger 2020-02-17 14:37 ` Janosch Frank 2020-02-14 22:26 ` [PATCH v2 20/42] KVM: S390: protvirt: Introduce instruction data area bounce buffer Christian Borntraeger 2020-02-17 11:08 ` David Hildenbrand 2020-02-17 14:47 ` Janosch Frank 2020-02-17 15:00 ` Christian Borntraeger 2020-02-17 15:38 ` Janosch Frank 2020-02-17 16:58 ` Christian Borntraeger 2020-02-14 22:26 ` [PATCH v2 21/42] KVM: s390: protvirt: handle secure guest prefix pages Christian Borntraeger 2020-02-17 11:11 ` David Hildenbrand 2020-02-14 22:26 ` [PATCH v2 22/42] KVM: s390/mm: handle guest unpin events Christian Borntraeger 2020-02-17 14:23 ` David Hildenbrand 2020-02-14 22:26 ` [PATCH v2 23/42] KVM: s390: protvirt: Write sthyi data to instruction data area Christian Borntraeger 2020-02-17 14:24 ` David Hildenbrand 2020-02-17 18:40 ` Christian Borntraeger 2020-02-17 19:16 ` David Hildenbrand 2020-02-14 22:26 ` [PATCH v2 24/42] KVM: s390: protvirt: STSI handling Christian Borntraeger 2020-02-18 8:35 ` David Hildenbrand 2020-02-18 8:44 ` Christian Borntraeger 2020-02-18 9:08 ` David Hildenbrand 2020-02-18 9:11 ` Christian Borntraeger 2020-02-18 9:13 ` David Hildenbrand 2020-02-14 22:26 ` [PATCH v2 25/42] KVM: s390: protvirt: disallow one_reg Christian Borntraeger 2020-02-18 8:40 ` David Hildenbrand 2020-02-18 8:57 ` Christian Borntraeger 2020-02-14 22:26 ` [PATCH v2 26/42] KVM: s390: protvirt: Do only reset registers that are accessible Christian Borntraeger 2020-02-18 8:42 ` David Hildenbrand 2020-02-18 9:20 ` Christian Borntraeger 2020-02-18 9:28 ` David Hildenbrand 2020-02-14 22:26 ` [PATCH v2 27/42] KVM: s390: protvirt: Only sync fmt4 registers Christian Borntraeger 2020-02-14 22:26 ` [PATCH v2 28/42] KVM: s390: protvirt: Add program exception injection Christian Borntraeger 2020-02-18 9:33 ` David Hildenbrand 2020-02-18 9:37 ` Christian Borntraeger 2020-02-18 9:39 ` David Hildenbrand 2020-02-14 22:26 ` [PATCH v2 29/42] KVM: s390: protvirt: Add diag 308 subcode 8 - 10 handling Christian Borntraeger 2020-02-18 9:38 ` David Hildenbrand 2020-02-19 12:45 ` Christian Borntraeger 2020-02-14 22:26 ` [PATCH v2 30/42] KVM: s390: protvirt: UV calls in support of diag308 0, 1 Christian Borntraeger 2020-02-18 9:44 ` David Hildenbrand 2020-02-19 11:53 ` Christian Borntraeger 2020-02-14 22:26 ` [PATCH v2 31/42] KVM: s390: protvirt: Report CPU state to Ultravisor Christian Borntraeger 2020-02-18 9:48 ` David Hildenbrand 2020-02-19 19:36 ` Christian Borntraeger 2020-02-19 19:46 ` Christian Borntraeger 2020-02-20 10:52 ` David Hildenbrand 2020-02-14 22:26 ` [PATCH v2 32/42] KVM: s390: protvirt: Support cmd 5 operation state Christian Borntraeger 2020-02-18 9:50 ` David Hildenbrand 2020-02-19 11:06 ` Christian Borntraeger 2020-02-19 11:08 ` David Hildenbrand 2020-02-14 22:26 ` [PATCH v2 33/42] KVM: s390: protvirt: Mask PSW interrupt bits for interception 104 and 112 Christian Borntraeger 2020-02-18 9:53 ` David Hildenbrand 2020-02-18 10:02 ` David Hildenbrand 2020-02-18 10:05 ` Christian Borntraeger 2020-02-14 22:26 ` [PATCH v2 34/42] KVM: s390: protvirt: do not inject interrupts after start Christian Borntraeger 2020-02-18 9:53 ` David Hildenbrand 2020-02-18 10:02 ` David Hildenbrand 2020-02-14 22:26 ` [PATCH v2 35/42] KVM: s390: protvirt: Add UV cpu reset calls Christian Borntraeger 2020-02-18 9:54 ` David Hildenbrand 2020-02-14 22:26 ` [PATCH v2 36/42] DOCUMENTATION: Protected virtual machine introduction and IPL Christian Borntraeger 2020-02-14 22:26 ` [PATCH v2 37/42] s390/uv: Fix handling of length extensions (already in s390 tree) Christian Borntraeger 2020-02-14 22:26 ` [PATCH v2 38/42] s390: protvirt: Add sysfs firmware interface for Ultravisor information Christian Borntraeger 2020-02-14 22:26 ` [PATCH v2 39/42] example for future extension: mm:gup/writeback: add callbacks for inaccessible pages: error cases Christian Borntraeger 2020-02-18 16:25 ` Will Deacon 2020-02-18 16:30 ` Christian Borntraeger 2020-02-18 16:33 ` Will Deacon 2020-02-14 22:26 ` [PATCH v2 40/42] example for future extension: mm:gup/writeback: add callbacks for inaccessible pages: source indication Christian Borntraeger 2020-02-17 14:15 ` Ulrich Weigand 2020-02-17 14:38 ` Christian Borntraeger 2020-02-14 22:26 ` [PATCH v2 41/42] potential fixup for "s390/mm: provide memory management functions for protected KVM guests" Christian Borntraeger 2020-02-14 22:26 ` [PATCH v2 42/42] KVM: s390: rstify new ioctls in api.rst Christian Borntraeger
Reply instructions: You may reply publicly to this message via plain-text email using any one of the following methods: * Save the following mbox file, import it into your mail client, and reply-to-all from there: mbox Avoid top-posting and favor interleaved quoting: https://en.wikipedia.org/wiki/Posting_style#Interleaved_style * Reply using the --to, --cc, and --in-reply-to switches of git-send-email(1): git send-email \ --in-reply-to=45954200-ccfe-cfac-200d-d1b903d9fc39@de.ibm.com \ --to=borntraeger@de.ibm.com \ --cc=Ulrich.Weigand@de.ibm.com \ --cc=cohuck@redhat.com \ --cc=david@redhat.com \ --cc=frankja@linux.vnet.ibm.com \ --cc=gor@linux.ibm.com \ --cc=imbrenda@linux.ibm.com \ --cc=kvm@vger.kernel.org \ --cc=linux-s390@vger.kernel.org \ --cc=mimu@linux.ibm.com \ --cc=thuth@redhat.com \ /path/to/YOUR_REPLY https://kernel.org/pub/software/scm/git/docs/git-send-email.html * If your mail client supports setting the In-Reply-To header via mailto: links, try the mailto: link
KVM Archive on lore.kernel.org Archives are clonable: git clone --mirror https://lore.kernel.org/kvm/0 kvm/git/0.git # If you have public-inbox 1.1+ installed, you may # initialize and index your mirror using the following commands: public-inbox-init -V2 kvm kvm/ https://lore.kernel.org/kvm \ kvm@vger.kernel.org public-inbox-index kvm Example config snippet for mirrors Newsgroup available over NNTP: nntp://nntp.lore.kernel.org/org.kernel.vger.kvm AGPL code for this site: git clone https://public-inbox.org/public-inbox.git