With every new Hyper-V Enlightenment we implement we're forced to add a KVM_CAP_HYPERV_* capability. While this approach works it is fairly inconvenient: the majority of the enlightenments we do have corresponding CPUID feature bit(s) and userspace has to know this anyways to be able to expose the feature to the guest. Add KVM_GET_SUPPORTED_HV_CPUID ioctl (backed by KVM_CAP_HYPERV_CPUID, "one cap to rule them all!") returning all Hyper-V CPUID feature leaves. Using the existing KVM_GET_SUPPORTED_CPUID doesn't seem to be possible: Hyper-V CPUID feature leaves intersect with KVM's (e.g. 0x40000000, 0x40000001) and we would probably confuse userspace in case we decide to return these twice. KVM_CAP_HYPERV_CPUID's number is interim: we're intended to drop KVM_CAP_HYPERV_STIMER_DIRECT and use its number instead. Suggested-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
There are two problems with KVM_GET_DIRTY_LOG. First, and less important,
it can take kvm->mmu_lock for an extended period of time. Second, its user
can actually see many false positives in some cases. The latter is due
to a benign race like this:
1. KVM_GET_DIRTY_LOG returns a set of dirty pages and write protects
them.
2. The guest modifies the pages, causing them to be marked ditry.
3. Userspace actually copies the pages.
4. KVM_GET_DIRTY_LOG returns those pages as dirty again, even though
they were not written to since (3).
This is especially a problem for large guests, where the time between
(1) and (3) can be substantial. This patch introduces a new
capability which, when enabled, makes KVM_GET_DIRTY_LOG not
write-protect the pages it returns. Instead, userspace has to
explicitly clear the dirty log bits just before using the content
of the page. The new KVM_CLEAR_DIRTY_LOG ioctl can also operate on a
64-page granularity rather than requiring to sync a full memslot;
this way, the mmu_lock is taken for small amounts of time, and
only a small amount of time will pass between write protection
of pages and the sending of their content.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
KVM/arm updates for 4.20 - Improved guest IPA space support (32 to 52 bits) - RAS event delivery for 32bit - PMU fixes - Guest entry hardening - Various cleanups
This is a per-VM capability which can be enabled by userspace so that the faulting linear address will be included with the information about a pending #PF in L2, and the "new DR6 bits" will be included with the information about a pending #DB in L2. With this capability enabled, the L1 hypervisor can now intercept #PF before CR2 is modified. Under VMX, the L1 hypervisor can now intercept #DB before DR6 and DR7 are modified. When userspace has enabled KVM_CAP_EXCEPTION_PAYLOAD, it should generally provide an appropriate payload when injecting a #PF or #DB exception via KVM_SET_VCPU_EVENTS. However, to support restoring old checkpoints, this payload is not required. Note that bit 16 of the "new DR6 bits" is set to indicate that a debug exception (#DB) or a breakpoint exception (#BP) occurred inside an RTM region while advanced debugging of RTM transactional regions was enabled. This is the reverse of DR6.RTM, which is cleared in this scenario. This capability also enables exception.pending in struct kvm_vcpu_events, which allows userspace to distinguish between pending and injected exceptions. Reported-by: Jim Mattson <jmattson@google.com> Suggested-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Jim Mattson <jmattson@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Enlightened VMCS is opt-in. The current version does not contain all fields supported by nested VMX so we must not advertise the corresponding VMX features if enlightened VMCS is enabled. Userspace is given the enlightened VMCS version supported by KVM as part of enabling KVM_CAP_HYPERV_ENLIGHTENED_VMCS. The version is to be advertised to the nested hypervisor, currently done via a cpuid leaf for Hyper-V. Suggested-by: Ladi Prosek <lprosek@redhat.com> Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> Reviewed-by: Liran Alon <liran.alon@oracle.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Coalesced pio is based on coalesced mmio and can be used for some port like rtc port, pci-host config port and so on. Specially in case of rtc as coalesced pio, some versions of windows guest access rtc frequently because of rtc as system tick. guest access rtc like this: write register index to 0x70, then write or read data from 0x71. writing 0x70 port is just as index and do nothing else. So we can use coalesced pio to handle this scene to reduce VM-EXIT time. When starting and closing a virtual machine, it will access pci-host config port frequently. So setting these port as coalesced pio can reduce startup and shutdown time. without my patch, get the vm-exit time of accessing rtc 0x70 and piix 0xcf8 using perf tools: (guest OS : windows 7 64bit) IO Port Access Samples Samples% Time% Min Time Max Time Avg time 0x70:POUT 86 30.99% 74.59% 9us 29us 10.75us (+- 3.41%) 0xcf8:POUT 1119 2.60% 2.12% 2.79us 56.83us 3.41us (+- 2.23%) with my patch IO Port Access Samples Samples% Time% Min Time Max Time Avg time 0x70:POUT 106 32.02% 29.47% 0us 10us 1.57us (+- 7.38%) 0xcf8:POUT 1065 1.67% 0.28% 0.41us 65.44us 0.66us (+- 10.55%) Signed-off-by: Peng Hao <peng.hao2@zte.com.cn> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Using hypercall for sending IPIs is faster because this allows to specify any number of vCPUs (even > 64 with sparse CPU set), the whole procedure will take only one VMEXIT. Current Hyper-V TLFS (v5.0b) claims that HvCallSendSyntheticClusterIpi hypercall can't be 'fast' (passing parameters through registers) but apparently this is not true, Windows always uses it as 'fast' so we need to support that. Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This adds a KVM_PPC_NO_HASH flag to the flags field of the kvm_ppc_smmu_info struct, and arranges for it to be set when running as a nested hypervisor, as an unambiguous indication to userspace that HPT guests are not supported. Reporting the KVM_CAP_PPC_MMU_HASH_V3 capability as false could be taken as indicating only that the new HPT features in ISA V3.0 are not supported, leaving it ambiguous whether pre-V3.0 HPT features are supported. Reviewed-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
With this, userspace can enable a KVM-HV guest to run nested guests under it. The administrator can control whether any nested guests can be run; setting the "nested" module parameter to false prevents any guests becoming nested hypervisors (that is, any attempt to enable the nested capability on a guest will fail). Guests which are already nested hypervisors will continue to be so. Reviewed-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
Allow specifying the physical address size limit for a new VM via the kvm_type argument for the KVM_CREATE_VM ioctl. This allows us to finalise the stage2 page table as early as possible and hence perform the right checks on the memory slots without complication. The size is encoded as Log2(PA_Size) in bits[7:0] of the type field. For backward compatibility the value 0 is reserved and implies 40bits. Also, lift the limit of the IPA to host limit and allow lower IPA sizes (e.g, 32). The userspace could check the extension KVM_CAP_ARM_VM_IPA_SIZE for the availability of this feature. The cap check returns the maximum limit for the physical address shift supported by the host. Cc: Marc Zyngier <marc.zyngier@arm.com> Cc: Christoffer Dall <cdall@kernel.org> Cc: Peter Maydell <peter.maydell@linaro.org> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Radim Krčmář <rkrcmar@redhat.com> Reviewed-by: Eric Auger <eric.auger@redhat.com> Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>