- 21 Jun, 2016 7 commits
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David Hildenbrand authored
Issuing STFLE is extremely rare. Instead of copying 2k on every VSIE call, let's do this lazily, when a guest 3 tries to execute STFLE. We can setup the block and retry. Unfortunately, we can't directly forward that facility list, as we only have a 31 bit address for the facility list designation. So let's use a DMA allocation for our vsie_page instead for now. Acked-by:
Christian Borntraeger <borntraeger@de.ibm.com> Signed-off-by:
David Hildenbrand <dahi@linux.vnet.ibm.com> Signed-off-by:
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David Hildenbrand authored
Introduced with ESOP, therefore available for the guest if it is allowed to use ESOP. Acked-by:
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David Hildenbrand authored
If guest 2 is allowed to use edat 1 / edat 2, it can also set it up for guest 3, so let's properly check and forward the edat cpuflags. Acked-by:
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David Hildenbrand authored
As soon as we forward an ibc to guest 2 (indicated via kvm->arch.model.ibc), he can also use it for guest 3. Let's properly round the ibc up/down, so we avoid any potential validity icpts from the underlying SIE, if it doesn't simply round the values. Acked-by:
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David Hildenbrand authored
In order to not always map the prefix, we have to take care of certain aspects that implicitly unmap the prefix: - Changes to the prefix address - Changes to MSO, because the HVA of the prefix is changed - Changes of the gmap shadow (e.g. unshadowed, asce or edat changes) By properly handling these cases, we can stop remapping the prefix when there is no reason to do so. This also allows us now to not acquire any gmap shadow locks when rerunning the vsie and still having a valid gmap shadow. Please note, to detect changing gmap shadows, we have to keep the reference of the gmap shadow. The address of a gmap shadow does otherwise not reliably indicate if the gmap shadow has changed (the memory chunk could get reused). Acked-by:
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David Hildenbrand authored
This patch adds basic support for nested virtualization on s390x, called VSIE (virtual SIE) and allows it to be used by the guest if the necessary facilities are supported by the hardware and enabled for the guest. In order to make this work, we have to shadow the sie control block provided by guest 2. In order to gain some performance, we have to reuse the same shadow blocks as good as possible. For now, we allow as many shadow blocks as we have VCPUs (that way, every VCPU can run the VSIE concurrently). We have to watch out for the prefix getting unmapped out of our shadow gmap and properly get the VCPU out of VSIE in that case, to fault the prefix pages back in. We use the PROG_REQUEST bit for that purpose. This patch is based on an initial prototype by Tobias Elpelt. Acked-by:
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David Hildenbrand authored
Let's introduce that helper. Signed-off-by:
Andrew Morton <akpm@linux-foundation.org> Signed-off-by:
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- 20 Jun, 2016 26 commits
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David Hildenbrand authored
Acked-by:
Heiko Carstens <heiko.carstens@de.ibm.com> Acked-by:
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David Hildenbrand authored
Nested virtualization will have to enable own gmaps. Current code would enable the wrong gmap whenever scheduled out and back in, therefore resulting in the wrong gmap being enabled. This patch reenables the last enabled gmap, therefore avoiding having to touch vcpu->arch.gmap when enabling a different gmap. Acked-by:
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David Hildenbrand authored
The default kvm gmap notifier doesn't have to handle shadow gmaps. So let's just directly exit in case we get notified about one. Acked-by:
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David Hildenbrand authored
Let's not fault in everything in read-write but limit it to read-only where possible. When restricting access rights, we already have the required protection level in our hands. When reading from guest 2 storage (gmap_read_table), it is obviously PROT_READ. When shadowing a pte, the required protection level is given via the guest 2 provided pte. Based on an initial patch by Martin Schwidefsky. Acked-by:
Martin Schwidefsky <schwidefsky@de.ibm.com> Signed-off-by:
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David Hildenbrand authored
It will be very helpful to have a mechanism to check without any locks if a given gmap shadow is still valid and matches the given properties. Acked-by:
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David Hildenbrand authored
For nested virtualization, we want to know if we are handling a protection exception, because these can directly be forwarded to the guest without additional checks. Acked-by:
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David Hildenbrand authored
We have no known user of real-space designation and only support it to be architecture compliant. Gmap shadows with real-space designation are never unshadowed automatically, as there is nothing to protect for the top level table. So let's simply limit the number of such shadows to one by removing existing ones on creation of another one. Acked-by:
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David Hildenbrand authored
We can easily support real-space designation just like EDAT1 and EDAT2. So guest2 can provide for guest3 an asce with the real-space control being set. We simply have to allocate the biggest page table possible and fake all levels. There is no protection to consider. If we exceed guest memory, vsie code will inject an addressing exception (via program intercept). In the future, we could limit the fake table level to the gmap page table. As the top level page table can never go away, such gmap shadows will never get unshadowed, we'll have to come up with another way to limit the number of kept gmap shadows. Acked-by:
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David Hildenbrand authored
Just like we already do with ste protection, let's take rte protection into account. This way, the host pte doesn't have to be mapped writable. Acked-by:
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David Hildenbrand authored
If the guest is enabled for EDAT2, we can easily create shadows for guest2 -> guest3 provided tables that make use of EDAT2. If guest2 references a 2GB page, this memory looks consecutive for guest2, but it does not have to be so for us. Therefore we have to create fake segment and page tables. This works just like EDAT1 support, so page tables are removed when the parent table (r3t table entry) is changed. We don't hve to care about: - ACCF-Validity Control in RTTE - Access-Control Bits in RTTE - Fetch-Protection Bit in RTTE - Common-Region Bit in RTTE Just like for EDAT1, all bits might be dropped and there is no guaranteed that they are active. Acked-by:
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David Hildenbrand authored
If the guest is enabled for EDAT1, we can easily create shadows for guest2 -> guest3 provided tables that make use of EDAT1. If guest2 references a 1MB page, this memory looks consecutive for guest2, but it might not be so for us. Therefore we have to create fake page tables. We can easily add that to our existing infrastructure. The invalidation mechanism will make sure that fake page tables are removed when the parent table (sgt table entry) is changed. As EDAT1 also introduced protection on all page table levels, we have to also shadow these correctly. We don't have to care about: - ACCF-Validity Control in STE - Access-Control Bits in STE - Fetch-Protection Bit in STE - Common-Segment Bit in STE As all bits might be dropped and there is no guaranteed that they are active ("unpredictable whether the CPU uses these bits", "may be used"). Without using EDAT1 in the shadow ourselfes (STE-format control == 0), simply shadowing these bits would not be enough. They would be ignored. Please note that we are using the "fake" flag to make this look consistent with further changes (EDAT2, real-space designation support) and don't let the shadow functions handle fc=1 stes. In the future, with huge pages in the host, gmap_shadow_pgt() could simply try to map a huge host page if "fake" is set to one and indicate via return value that no lower fake tables / shadow ptes are required. Acked-by: -
David Hildenbrand authored
In preparation for EDAT1/EDAT2 support for gmap shadows, we have to store the requested edat level in the gmap shadow. The edat level used during shadow translation is a property of the gmap shadow. Depending on that level, the gmap shadow will look differently for the same guest tables. We have to store it internally in order to support it later. Acked-by:
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David Hildenbrand authored
If a guest ste is read-only, it doesn't make sense to force the ptes in as writable in the host. If the source page is read-only in the host, it won't have to be made writable. Please note that if the source page is not available, it will still be faulted in writable. This can be changed internally later on. If ste protection is removed, underlying shadow tables are also removed, therefore this change does not affect the guest. Acked-by:
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David Hildenbrand authored
Let's take the ipte_lock while working on guest 2 provided page table, just like the other gaccess functions. Acked-by:
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David Hildenbrand authored
As gmap shadows contains correct protection permissions, protection exceptons can directly be forwarded to guest 3. If we would encounter a protection exception while faulting, the next guest 3 run will automatically handle that for us. Keep the dat_protection logic in place, as it will be helpful later. Acked-by:
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David Hildenbrand authored
Instead of doing it in the caller, let's just take the mmap_sem in kvm_s390_shadow_fault(). By taking it as read, we allow parallel faulting on shadow page tables, gmap shadow code is prepared for that. Acked-by:
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David Hildenbrand authored
Before any thread is allowed to use a gmap_shadow, it has to be fully initialized. However, for invalidation to work properly, we have to register the new gmap_shadow before we protect the parent gmap table. Because locking is tricky, and we have to avoid duplicate gmaps, let's introduce an initialized field, that signalizes other threads if that gmap_shadow can already be used or if they have to retry. Let's properly return errors using ERR_PTR() instead of simply returning NULL, so a caller can properly react on the error. Acked-by:
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David Hildenbrand authored
We have to unlock sg->guest_table_lock in order to call gmap_protect_rmap(). If we sleep just before that call, another VCPU might pick up that shadowed page table (while it is not protected yet) and use it. In order to avoid these races, we have to introduce a third state - "origin set but still invalid" for an entry. This way, we can avoid another thread already using the entry before the table is fully protected. As soon as everything is set up, we can clear the invalid bit - if we had no race with the unshadowing code. Suggested-by:
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David Hildenbrand authored
We really want to avoid manually handling protection for nested virtualization. By shadowing pages with the protection the guest asked us for, the SIE can handle most protection-related actions for us (e.g. special handling for MVPG) and we can directly forward protection exceptions to the guest. PTEs will now always be shadowed with the correct _PAGE_PROTECT flag. Unshadowing will take care of any guest changes to the parent PTE and any host changes to the host PTE. If the host PTE doesn't have the fitting access rights or is not available, we have to fix it up. Acked-by:
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David Hildenbrand authored
For now, the tlb of shadow gmap is only flushed when the parent is removed, not when it is removed upfront. Therefore other shadow gmaps can reuse the tables without the tlb getting flushed. Fix this by simply flushing the tlb 1. Before the shadow tables are removed (analogouos to other unshadow functions) 2. When the gmap is freed and therefore the top level pages are freed. Acked-by:
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Martin Schwidefsky authored
This patch introduces function kvm_s390_shadow_fault() used to resolve a fault on a shadow gmap. This function will do validity checking and build up the shadow page table hierarchy in order to fault in the requested page into the shadow page table structure. If an exception occurs while shadowing, guest 2 has to be notified about it using either an exception or a program interrupt intercept. If concurrent unshadowing occurres, this function will simply return with -EAGAIN and the caller has to retry. Reviewed-by:
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Martin Schwidefsky authored
For a nested KVM guest the outer KVM host needs to create shadow page tables for the nested guest. This patch adds the basic support to the guest address space (gmap) code. For each guest address space the inner KVM host creates, the first outer KVM host needs to create shadow page tables. The address space is identified by the ASCE loaded into the control register 1 at the time the inner SIE instruction for the second nested KVM guest is executed. The outer KVM host creates the shadow tables starting with the table identified by the ASCE on a on-demand basis. The outer KVM host will get repeated faults for all the shadow tables needed to run the second KVM guest. While a shadow page table for the second KVM guest is active the access to the origin region, segment and page tables needs to be restricted for the first KVM guest. For region and segment and page tables the first KVM guest may read the memory, but write attempt has to lead to an unshadow. This is done using the page invalid and read-only bits in the page table of the first KVM guest. If the first guest re-accesses one of the origin pages of a shadow, it gets a fault and the affected parts of the shadow page table hierarchy needs to be removed again. PGSTE tables don't have to be shadowed, as all interpretation assist can't deal with the invalid bits in the shadow pte being set differently than the original ones provided by the first KVM guest. Many bug fixes and improvements by David Hildenbrand. Reviewed-by:
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Martin Schwidefsky authored
Let's use a reference counter mechanism to control the lifetime of gmap structures. This will be needed for further changes related to gmap shadows. Reviewed-by:
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Martin Schwidefsky authored
The current gmap pte notifier forces a pte into to a read-write state. If the pte is invalidated the gmap notifier is called to inform KVM that the mapping will go away. Extend this approach to allow read-write, read-only and no-access as possible target states and call the pte notifier for any change to the pte. This mechanism is used to temporarily set specific access rights for a pte without doing the heavy work of a true mprotect call. Reviewed-by:
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Martin Schwidefsky authored
The gmap notifier list and the gmap list in the mm_struct change rarely. Use RCU to optimize the reader of these lists. Reviewed-by:
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Martin Schwidefsky authored
Pass an address range to the page table invalidation notifier for KVM. This allows to notify changes that affect a larger virtual memory area, e.g. for 1MB pages. Reviewed-by:
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- 16 Jun, 2016 5 commits
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Yunhong Jiang authored
Hook the VMX preemption timer to the "hv timer" functionality added by the previous patch. This includes: checking if the feature is supported, if the feature is broken on the CPU, the hooks to setup/clean the VMX preemption timer, arming the timer on vmentry and handling the vmexit. A module parameter states if the VMX preemption timer should be utilized. Signed-off-by:
Yunhong Jiang <yunhong.jiang@intel.com> [Move hv_deadline_tsc to struct vcpu_vmx, use -1 as the "unset" value. Put all VMX bits here. Enable it by default #yolo. - Paolo] Signed-off-by:
Paolo Bonzini <pbonzini@redhat.com>
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Yunhong Jiang authored
Prepare to switch from preemption timer to hrtimer in the vmx_pre/post_block. Current functions are only for posted interrupt, rename them accordingly. Signed-off-by:
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Yunhong Jiang authored
The VMX preemption timer can be used to virtualize the TSC deadline timer. The VMX preemption timer is armed when the vCPU is running, and a VMExit will happen if the virtual TSC deadline timer expires. When the vCPU thread is blocked because of HLT, KVM will switch to use an hrtimer, and then go back to the VMX preemption timer when the vCPU thread is unblocked. This solution avoids the complex OS's hrtimer system, and the host timer interrupt handling cost, replacing them with a little math (for guest->host TSC and host TSC->preemption timer conversion) and a cheaper VMexit. This benefits latency for isolated pCPUs. [A word about performance... Yunhong reported a 30% reduction in average latency from cyclictest. I made a similar test with tscdeadline_latency from kvm-unit-tests, and measured - ~20 clock cycles loss (out of ~3200, so less than 1% but still statistically significant) in the worst case where the test halts just after programming the TSC deadline timer - ~800 clock cycles gain (25% reduction in latency) in the best case where the test busy waits. I removed the VMX bits from Yunhong's patch, to concentrate them in the next patch - Paolo] Signed-off-by:
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Yunhong Jiang authored
The function to start the tsc deadline timer virtualization will be used also by the pre_block hook when we use the preemption timer; change it to a separate function. No logic changes. Signed-off-by:
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Paolo Bonzini authored
The new created_vcpus field avoids possible races between enabling capabilities and creating VCPUs. Acked-by:
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- 15 Jun, 2016 2 commits
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Paolo Bonzini authored
The new created_vcpus field makes it possible to avoid the race between irqchip and VCPU creation in a much nicer way; just check under kvm->lock whether a VCPU has already been created. We can then remove KVM_APIC_ARCHITECTURE too, because at this point the symbol is only governing the default definition of kvm_vcpu_compatible. Signed-off-by: -
Paolo Bonzini authored
The race between creating the irqchip and the first VCPU is currently fixed by checking the presence of an irqchip before updating kvm->online_vcpus, and undoing the whole VCPU creation if someone created the irqchip in the meanwhile. Instead, introduce a new field in struct kvm that will count VCPUs under a mutex, without the atomic access and memory ordering that we need elsewhere to protect the vcpus array. This also plugs the race and is more easily applicable in all similar circumstances. Reviewed-by:
Cornelia Huck <cornelia.huck@de.ibm.com> Signed-off-by:
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