user/sven/linux.git/Documentation/virtual, branch v4.14.41

arm/arm64: KVM: Add PSCI version selection API

2018-05-01T19:58:27Z

commit 85bd0ba1ff9875798fad94218b627ea9f768f3c3 upstream. Although we've implemented PSCI 0.1, 0.2 and 1.0, we expose either 0.1 or 1.0 to a guest, defaulting to the latest version of the PSCI implementation that is compatible with the requested version. This is no different from doing a firmware upgrade on KVM. But in order to give a chance to hypothetical badly implemented guests that would have a fit by discovering something other than PSCI 0.2, let's provide a new API that allows userspace to pick one particular version of the API. This is implemented as a new class of "firmware" registers, where we expose the PSCI version. This allows the PSCI version to be save/restored as part of a guest migration, and also set to any supported version if the guest requires it. Cc: stable@vger.kernel.org #4.16 Reviewed-by: Christoffer Dall Signed-off-by: Marc Zyngier Signed-off-by: Greg Kroah-Hartman

KVM: PPC: Book3S HV: Enable migration of decrementer register

2018-04-26T09:02:04Z

[ Upstream commit 5855564c8ab2d9cefca7b2933bd19818eb795e40 ] This adds a register identifier for use with the one_reg interface to allow the decrementer expiry time to be read and written by userspace. The decrementer expiry time is in guest timebase units and is equal to the sum of the decrementer and the guest timebase. (The expiry time is used rather than the decrementer value itself because the expiry time is not constantly changing, though the decrementer value is, while the guest vcpu is not running.) Without this, a guest vcpu migrated to a new host will see its decrementer set to some random value. On POWER8 and earlier, the decrementer is 32 bits wide and counts down at 512MHz, so the guest vcpu will potentially see no decrementer interrupts for up to about 4 seconds, which will lead to a stall. With POWER9, the decrementer is now 56 bits side, so the stall can be much longer (up to 2.23 years) and more noticeable. To help work around the problem in cases where userspace has not been updated to migrate the decrementer expiry time, we now set the default decrementer expiry at vcpu creation time to the current time rather than the maximum possible value. This should mean an immediate decrementer interrupt when a migrated vcpu starts running. In cases where the decrementer is 32 bits wide and more than 4 seconds elapse between the creation of the vcpu and when it first runs, the decrementer would have wrapped around to positive values and there may still be a stall - but this is no worse than the current situation. In the large-decrementer case, we are sure to get an immediate decrementer interrupt (assuming the time from vcpu creation to first run is less than 2.23 years) and we thus avoid a very long stall. Signed-off-by: Paul Mackerras Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

KVM: x86: fix backward migration with async_PF

2018-03-11T15:23:23Z

commit fe2a3027e74e40a3ece3a4c1e4e51403090a907a upstream. Guests on new hypersiors might set KVM_ASYNC_PF_DELIVERY_AS_PF_VMEXIT bit when enabling async_PF, but this bit is reserved on old hypervisors, which results in a failure upon migration. To avoid breaking different cases, we are checking for CPUID feature bit before enabling the feature and nothing else. Fixes: 52a5c155cf79 ("KVM: async_pf: Let guest support delivery of async_pf from guest mode") Cc: Reviewed-by: Wanpeng Li Reviewed-by: David Hildenbrand Signed-off-by: Radim Krčmář Signed-off-by: Paolo Bonzini [jwang: port to 4.14] Signed-off-by: Jack Wang Signed-off-by: Greg Kroah-Hartman

Merge tag 'kvm-arm-for-v4.14' of git://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm

2017-09-07T16:22:04Z

KVM/ARM Changes for v4.14 Two minor cleanups and improvements, a fix for decoding external abort types from guests, and added support for migrating the active priority of interrupts when running a GICv2 guest on a GICv3 host.

KVM: arm/arm64: Support uaccess of GICC_APRn

2017-09-05T15:33:39Z

When migrating guests around we need to know the active priorities to ensure functional virtual interrupt prioritization by the GIC. This commit clarifies the API and how active priorities of interrupts in different groups are represented, and implements the accessor functions for the uaccess register range. We live with a slight layering violation in accessing GICv3 data structures from vgic-mmio-v2.c, because anything else just adds too much complexity for us to deal with (it's not like there's a benefit elsewhere in the code of an intermediate representation as is the case with the VMCR). We accept this, because while doing v3 processing from a file named something-v2.c can look strange at first, this really is specific to dealing with the user space interface for something that looks like a GICv2. Reviewed-by: Marc Zyngier Signed-off-by: Christoffer Dall

KVM: s390: Multiple Epoch Facility support

2017-08-29T13:15:54Z

Allow for the enablement of MEF and the support for the extended epoch in SIE and VSIE for the extended guest TOD-Clock. A new interface is used for getting/setting a guest's extended TOD-Clock that uses a single ioctl invocation, KVM_S390_VM_TOD_EXT. Since the host time is a moving target that might see an epoch switch or STP sync checks we need an atomic ioctl and cannot use the exisiting two interfaces. The old method of getting and setting the guest TOD-Clock is still retained and is used when the old ioctls are called. Signed-off-by: Collin L. Walling Reviewed-by: Janosch Frank Reviewed-by: Claudio Imbrenda Reviewed-by: Jason J. Herne Reviewed-by: Cornelia Huck Signed-off-by: Christian Borntraeger

kvm: x86: hyperv: make VP_INDEX managed by userspace

2017-07-14T14:28:18Z

Hyper-V identifies vCPUs by Virtual Processor Index, which can be queried via HV_X64_MSR_VP_INDEX msr. It is defined by the spec as a sequential number which can't exceed the maximum number of vCPUs per VM. APIC ids can be sparse and thus aren't a valid replacement for VP indices. Current KVM uses its internal vcpu index as VP_INDEX. However, to make it predictable and persistent across VM migrations, the userspace has to control the value of VP_INDEX. This patch achieves that, by storing vp_index explicitly on vcpu, and allowing HV_X64_MSR_VP_INDEX to be set from the host side. For compatibility it's initialized to KVM vcpu index. Also a few variables are renamed to make clear distinction betweed this Hyper-V vp_index and KVM vcpu_id (== APIC id). Besides, a new capability, KVM_CAP_HYPERV_VP_INDEX, is added to allow the userspace to skip attempting msr writes where unsupported, to avoid spamming error logs. Signed-off-by: Roman Kagan Signed-off-by: Radim Krčmář

KVM: async_pf: Let guest support delivery of async_pf from guest mode

2017-07-14T12:26:16Z

Adds another flag bit (bit 2) to MSR_KVM_ASYNC_PF_EN. If bit 2 is 1, async page faults are delivered to L1 as #PF vmexits; if bit 2 is 0, kvm_can_do_async_pf returns 0 if in guest mode. This is similar to what svm.c wanted to do all along, but it is only enabled for Linux as L1 hypervisor. Foreign hypervisors must never receive async page faults as vmexits, because they'd probably be very confused about that. Cc: Paolo Bonzini Cc: Radim Krčmář Signed-off-by: Wanpeng Li Signed-off-by: Radim Krčmář

kvm: x86: hyperv: add KVM_CAP_HYPERV_SYNIC2

2017-07-13T15:41:04Z

There is a flaw in the Hyper-V SynIC implementation in KVM: when message page or event flags page is enabled by setting the corresponding msr, KVM zeroes it out. This is problematic because on migration the corresponding MSRs are loaded on the destination, so the content of those pages is lost. This went unnoticed so far because the only user of those pages was in-KVM hyperv synic timers, which could continue working despite that zeroing. Newer QEMU uses those pages for Hyper-V VMBus implementation, and zeroing them breaks the migration. Besides, in newer QEMU the content of those pages is fully managed by QEMU, so zeroing them is undesirable even when writing the MSRs from the guest side. To support this new scheme, introduce a new capability, KVM_CAP_HYPERV_SYNIC2, which, when enabled, makes sure that the synic pages aren't zeroed out in KVM. Signed-off-by: Roman Kagan Signed-off-by: Radim Krčmář

kvm: x86: mmu: allow A/D bits to be disabled in an mmu

2017-07-03T09:19:54Z

Adds the plumbing to disable A/D bits in the MMU based on a new role bit, ad_disabled. When A/D is disabled, the MMU operates as though A/D aren't available (i.e., using access tracking faults instead). To avoid SP -> kvm_mmu_page.role.ad_disabled lookups all over the place, A/D disablement is now stored in the SPTE. This state is stored in the SPTE by tweaking the use of SPTE_SPECIAL_MASK for access tracking. Rather than just setting SPTE_SPECIAL_MASK when an access-tracking SPTE is non-present, we now always set SPTE_SPECIAL_MASK for access-tracking SPTEs. Signed-off-by: Peter Feiner [Use role.ad_disabled even for direct (non-shadow) EPT page tables. Add documentation and a few MMU_WARN_ONs. - Paolo] Signed-off-by: Paolo Bonzini