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  1. 07 5月, 2021 5 次提交
  3. 03 5月, 2021 1 次提交
    • M
      KVM: nSVM: fix few bugs in the vmcb02 caching logic · c74ad08f
      由 Maxim Levitsky 提交于 
      * Define and use an invalid GPA (all ones) for init value of last
  and current nested vmcb physical addresses.

* Reset the current vmcb12 gpa to the invalid value when leaving
  the nested mode, similar to what is done on nested vmexit.

* Reset	the last seen vmcb12 address when disabling the nested SVM,
  as it relies on vmcb02 fields which are freed at that point.

Fixes: 4995a368 ("KVM: SVM: Use a separate vmcb for the nested L2 guest")
Signed-off-by: NMaxim Levitsky <mlevitsk@redhat.com>
Message-Id: <20210503125446.1353307-3-mlevitsk@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
      c74ad08f
  5. 22 4月, 2021 1 次提交
    • N
      KVM: x86: Support KVM VMs sharing SEV context · 54526d1f
      由 Nathan Tempelman 提交于 
      Add a capability for userspace to mirror SEV encryption context from
one vm to another. On our side, this is intended to support a
Migration Helper vCPU, but it can also be used generically to support
other in-guest workloads scheduled by the host. The intention is for
the primary guest and the mirror to have nearly identical memslots.

The primary benefits of this are that:
1) The VMs do not share KVM contexts (think APIC/MSRs/etc), so they
can't accidentally clobber each other.
2) The VMs can have different memory-views, which is necessary for post-copy
migration (the migration vCPUs on the target need to read and write to
pages, when the primary guest would VMEXIT).

This does not change the threat model for AMD SEV. Any memory involved
is still owned by the primary guest and its initial state is still
attested to through the normal SEV_LAUNCH_* flows. If userspace wanted
to circumvent SEV, they could achieve the same effect by simply attaching
a vCPU to the primary VM.
This patch deliberately leaves userspace in charge of the memslots for the
mirror, as it already has the power to mess with them in the primary guest.

This patch does not support SEV-ES (much less SNP), as it does not
handle handing off attested VMSAs to the mirror.

For additional context, we need a Migration Helper because SEV PSP
migration is far too slow for our live migration on its own. Using
an in-guest migrator lets us speed this up significantly.
Signed-off-by: NNathan Tempelman <natet@google.com>
Message-Id: <20210408223214.2582277-1-natet@google.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
      54526d1f
  7. 20 4月, 2021 4 次提交
  9. 19 4月, 2021 1 次提交
  11. 17 4月, 2021 4 次提交
  13. 19 3月, 2021 1 次提交
    • S
      KVM: x86: Protect userspace MSR filter with SRCU, and set atomically-ish · b318e8de
      由 Sean Christopherson 提交于 
      Fix a plethora of issues with MSR filtering by installing the resulting
filter as an atomic bundle instead of updating the live filter one range
at a time.  The KVM_X86_SET_MSR_FILTER ioctl() isn't truly atomic, as
the hardware MSR bitmaps won't be updated until the next VM-Enter, but
the relevant software struct is atomically updated, which is what KVM
really needs.

Similar to the approach used for modifying memslots, make arch.msr_filter
a SRCU-protected pointer, do all the work configuring the new filter
outside of kvm->lock, and then acquire kvm->lock only when the new filter
has been vetted and created.  That way vCPU readers either see the old
filter or the new filter in their entirety, not some half-baked state.

Yuan Yao pointed out a use-after-free in ksm_msr_allowed() due to a
TOCTOU bug, but that's just the tip of the iceberg...

  - Nothing is __rcu annotated, making it nigh impossible to audit the
    code for correctness.
  - kvm_add_msr_filter() has an unpaired smp_wmb().  Violation of kernel
    coding style aside, the lack of a smb_rmb() anywhere casts all code
    into doubt.
  - kvm_clear_msr_filter() has a double free TOCTOU bug, as it grabs
    count before taking the lock.
  - kvm_clear_msr_filter() also has memory leak due to the same TOCTOU bug.

The entire approach of updating the live filter is also flawed.  While
installing a new filter is inherently racy if vCPUs are running, fixing
the above issues also makes it trivial to ensure certain behavior is
deterministic, e.g. KVM can provide deterministic behavior for MSRs with
identical settings in the old and new filters.  An atomic update of the
filter also prevents KVM from getting into a half-baked state, e.g. if
installing a filter fails, the existing approach would leave the filter
in a half-baked state, having already committed whatever bits of the
filter were already processed.

[*] https://lkml.kernel.org/r/20210312083157.25403-1-yaoyuan0329os@gmail.com

Fixes: 1a155254 ("KVM: x86: Introduce MSR filtering")
Cc: stable@vger.kernel.org
Cc: Alexander Graf <graf@amazon.com>
Reported-by: NYuan Yao <yaoyuan0329os@gmail.com>
Signed-off-by: NSean Christopherson <seanjc@google.com>
Message-Id: <20210316184436.2544875-2-seanjc@google.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
      b318e8de
  15. 18 3月, 2021 2 次提交
    • I
      x86: Fix various typos in comments · d9f6e12f
      由 Ingo Molnar 提交于 
      Fix ~144 single-word typos in arch/x86/ code comments.

Doing this in a single commit should reduce the churn.
Signed-off-by: NIngo Molnar <mingo@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: linux-kernel@vger.kernel.org
      d9f6e12f
    • V
      KVM: x86: hyper-v: Track Hyper-V TSC page status · cc9cfddb
      由 Vitaly Kuznetsov 提交于 
      Create an infrastructure for tracking Hyper-V TSC page status, i.e. if it
was updated from guest/host side or if we've failed to set it up (because
e.g. guest wrote some garbage to HV_X64_MSR_REFERENCE_TSC) and there's no
need to retry.

Also, in a hypothetical situation when we are in 'always catchup' mode for
TSC we can now avoid contending 'hv->hv_lock' on every guest enter by
setting the state to HV_TSC_PAGE_BROKEN after compute_tsc_page_parameters()
returns false.

Check for HV_TSC_PAGE_SET state instead of '!hv->tsc_ref.tsc_sequence' in
get_time_ref_counter() to properly handle the situation when we failed to
write the updated TSC page values to the guest.
Signed-off-by: NVitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20210316143736.964151-4-vkuznets@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
      cc9cfddb
  17. 15 3月, 2021 8 次提交
  19. 13 3月, 2021 1 次提交
    • M
      kvm: x86: annotate RCU pointers · 6fcd9cbc
      由 Muhammad Usama Anjum 提交于 
      This patch adds the annotation to fix the following sparse errors:
arch/x86/kvm//x86.c:8147:15: error: incompatible types in comparison expression (different address spaces):
arch/x86/kvm//x86.c:8147:15:    struct kvm_apic_map [noderef] __rcu *
arch/x86/kvm//x86.c:8147:15:    struct kvm_apic_map *
arch/x86/kvm//x86.c:10628:16: error: incompatible types in comparison expression (different address spaces):
arch/x86/kvm//x86.c:10628:16:    struct kvm_apic_map [noderef] __rcu *
arch/x86/kvm//x86.c:10628:16:    struct kvm_apic_map *
arch/x86/kvm//x86.c:10629:15: error: incompatible types in comparison expression (different address spaces):
arch/x86/kvm//x86.c:10629:15:    struct kvm_pmu_event_filter [noderef] __rcu *
arch/x86/kvm//x86.c:10629:15:    struct kvm_pmu_event_filter *
arch/x86/kvm//lapic.c:267:15: error: incompatible types in comparison expression (different address spaces):
arch/x86/kvm//lapic.c:267:15:    struct kvm_apic_map [noderef] __rcu *
arch/x86/kvm//lapic.c:267:15:    struct kvm_apic_map *
arch/x86/kvm//lapic.c:269:9: error: incompatible types in comparison expression (different address spaces):
arch/x86/kvm//lapic.c:269:9:    struct kvm_apic_map [noderef] __rcu *
arch/x86/kvm//lapic.c:269:9:    struct kvm_apic_map *
arch/x86/kvm//lapic.c:637:15: error: incompatible types in comparison expression (different address spaces):
arch/x86/kvm//lapic.c:637:15:    struct kvm_apic_map [noderef] __rcu *
arch/x86/kvm//lapic.c:637:15:    struct kvm_apic_map *
arch/x86/kvm//lapic.c:994:15: error: incompatible types in comparison expression (different address spaces):
arch/x86/kvm//lapic.c:994:15:    struct kvm_apic_map [noderef] __rcu *
arch/x86/kvm//lapic.c:994:15:    struct kvm_apic_map *
arch/x86/kvm//lapic.c:1036:15: error: incompatible types in comparison expression (different address spaces):
arch/x86/kvm//lapic.c:1036:15:    struct kvm_apic_map [noderef] __rcu *
arch/x86/kvm//lapic.c:1036:15:    struct kvm_apic_map *
arch/x86/kvm//lapic.c:1173:15: error: incompatible types in comparison expression (different address spaces):
arch/x86/kvm//lapic.c:1173:15:    struct kvm_apic_map [noderef] __rcu *
arch/x86/kvm//lapic.c:1173:15:    struct kvm_apic_map *
arch/x86/kvm//pmu.c:190:18: error: incompatible types in comparison expression (different address spaces):
arch/x86/kvm//pmu.c:190:18:    struct kvm_pmu_event_filter [noderef] __rcu *
arch/x86/kvm//pmu.c:190:18:    struct kvm_pmu_event_filter *
arch/x86/kvm//pmu.c:251:18: error: incompatible types in comparison expression (different address spaces):
arch/x86/kvm//pmu.c:251:18:    struct kvm_pmu_event_filter [noderef] __rcu *
arch/x86/kvm//pmu.c:251:18:    struct kvm_pmu_event_filter *
arch/x86/kvm//pmu.c:522:18: error: incompatible types in comparison expression (different address spaces):
arch/x86/kvm//pmu.c:522:18:    struct kvm_pmu_event_filter [noderef] __rcu *
arch/x86/kvm//pmu.c:522:18:    struct kvm_pmu_event_filter *
arch/x86/kvm//pmu.c:522:18: error: incompatible types in comparison expression (different address spaces):
arch/x86/kvm//pmu.c:522:18:    struct kvm_pmu_event_filter [noderef] __rcu *
arch/x86/kvm//pmu.c:522:18:    struct kvm_pmu_event_filter *
Signed-off-by: NMuhammad Usama Anjum <musamaanjum@gmail.com>
Message-Id: <20210305191123.GA497469@LEGION>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
      6fcd9cbc
  21. 03 3月, 2021 1 次提交
    • D
      KVM: x86/xen: Add support for vCPU runstate information · 30b5c851
      由 David Woodhouse 提交于 
      This is how Xen guests do steal time accounting. The hypervisor records
the amount of time spent in each of running/runnable/blocked/offline
states.

In the Xen accounting, a vCPU is still in state RUNSTATE_running while
in Xen for a hypercall or I/O trap, etc. Only if Xen explicitly schedules
does the state become RUNSTATE_blocked. In KVM this means that even when
the vCPU exits the kvm_run loop, the state remains RUNSTATE_running.

The VMM can explicitly set the vCPU to RUNSTATE_blocked by using the
KVM_XEN_VCPU_ATTR_TYPE_RUNSTATE_CURRENT attribute, and can also use
KVM_XEN_VCPU_ATTR_TYPE_RUNSTATE_ADJUST to retrospectively add a given
amount of time to the blocked state and subtract it from the running
state.

The state_entry_time corresponds to get_kvmclock_ns() at the time the
vCPU entered the current state, and the total times of all four states
should always add up to state_entry_time.
Co-developed-by: NJoao Martins <joao.m.martins@oracle.com>
Signed-off-by: NJoao Martins <joao.m.martins@oracle.com>
Signed-off-by: NDavid Woodhouse <dwmw@amazon.co.uk>
Message-Id: <20210301125309.874953-2-dwmw2@infradead.org>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
      30b5c851
  23. 26 2月, 2021 1 次提交
  25. 19 2月, 2021 5 次提交
  27. 09 2月, 2021 5 次提交
    • V
      KVM: x86: hyper-v: Make Hyper-V emulation enablement conditional · 8f014550
      由 Vitaly Kuznetsov 提交于 
      Hyper-V emulation is enabled in KVM unconditionally. This is bad at least
from security standpoint as it is an extra attack surface. Ideally, there
should be a per-VM capability explicitly enabled by VMM but currently it
is not the case and we can't mandate one without breaking backwards
compatibility. We can, however, check guest visible CPUIDs and only enable
Hyper-V emulation when "Hv#1" interface was exposed in
HYPERV_CPUID_INTERFACE.

Note, VMMs are free to act in any sequence they like, e.g. they can try
to set MSRs first and CPUIDs later so we still need to allow the host
to read/write Hyper-V specific MSRs unconditionally.
Signed-off-by: NVitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20210126134816.1880136-14-vkuznets@redhat.com>
[Add selftest vcpu_set_hv_cpuid API to avoid breaking xen_vmcall_test. - Paolo]
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
      8f014550
    • V
      KVM: x86: hyper-v: Allocate 'struct kvm_vcpu_hv' dynamically · 4592b7ea
      由 Vitaly Kuznetsov 提交于 
      Hyper-V context is only needed for guests which use Hyper-V emulation in
KVM (e.g. Windows/Hyper-V guests). 'struct kvm_vcpu_hv' is, however, quite
big, it accounts for more than 1/4 of the total 'struct kvm_vcpu_arch'
which is also quite big already. This all looks like a waste.

Allocate 'struct kvm_vcpu_hv' dynamically. This patch does not bring any
(intentional) functional change as we still allocate the context
unconditionally but it paves the way to doing that only when needed.
Signed-off-by: NVitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20210126134816.1880136-13-vkuznets@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
      4592b7ea
    • V
      KVM: Raise the maximum number of user memslots · 4fc096a9
      由 Vitaly Kuznetsov 提交于 
      Current KVM_USER_MEM_SLOTS limits are arch specific (512 on Power, 509 on x86,
32 on s390, 16 on MIPS) but they don't really need to be. Memory slots are
allocated dynamically in KVM when added so the only real limitation is
'id_to_index' array which is 'short'. We don't have any other
KVM_MEM_SLOTS_NUM/KVM_USER_MEM_SLOTS-sized statically defined structures.

Low KVM_USER_MEM_SLOTS can be a limiting factor for some configurations.
In particular, when QEMU tries to start a Windows guest with Hyper-V SynIC
enabled and e.g. 256 vCPUs the limit is hit as SynIC requires two pages per
vCPU and the guest is free to pick any GFN for each of them, this fragments
memslots as QEMU wants to have a separate memslot for each of these pages
(which are supposed to act as 'overlay' pages).
Signed-off-by: NVitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20210127175731.2020089-3-vkuznets@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
      4fc096a9
    • P
      KVM: x86: reading DR cannot fail · 29d6ca41
      由 Paolo Bonzini 提交于 
      kvm_get_dr and emulator_get_dr except an in-range value for the register
number so they cannot fail.  Change the return type to void.
Suggested-by: NSean Christopherson <seanjc@google.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
      29d6ca41
    • P
      KVM: x86: compile out TDP MMU on 32-bit systems · 897218ff
      由 Paolo Bonzini 提交于 
      The TDP MMU assumes that it can do atomic accesses to 64-bit PTEs.
Rather than just disabling it, compile it out completely so that it
is possible to use for example 64-bit xchg.

To limit the number of stubs, wrap all accesses to tdp_mmu_enabled
or tdp_mmu_page with a function.  Calls to all other functions in
tdp_mmu.c are eliminated and do not even reach the linker.
Reviewed-by: NSean Christopherson <seanjc@google.com>
Tested-by: NSean Christopherson <seanjc@google.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
      897218ff