A new capability (KVM_CAP_ARM_MTE) identifies that the kernel supports
granting a guest access to the tags, and provides a mechanism for the
VMM to enable it.
A new ioctl (KVM_ARM_MTE_COPY_TAGS) provides a simple way for a VMM to
access the tags of a guest without having to maintain a PROT_MTE mapping
in userspace. The above capability gates access to the ioctl.
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Steven Price <steven.price@arm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20210621111716.37157-7-steven.price@arm.com
This is a new version of KVM_GET_SREGS / KVM_SET_SREGS.
It has the following changes:
* Has flags for future extensions
* Has vcpu's PDPTRs, allowing to save/restore them on migration.
* Lacks obsolete interrupt bitmap (done now via KVM_SET_VCPU_EVENTS)
New capability, KVM_CAP_SREGS2 is added to signal
the userspace of this ioctl.
Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Message-Id: <20210607090203.133058-8-mlevitsk@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Add a new lock to protect the arch-specific fields of memslots if they
need to be modified in a kvm->srcu read critical section. A future
commit will use this lock to lazily allocate memslot rmaps for x86.
Signed-off-by: Ben Gardon <bgardon@google.com>
Message-Id: <20210518173414.450044-5-bgardon@google.com>
[Add Documentation/ hunk. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
When computing the access permissions of a shadow page, use the effective
permissions of the walk up to that point, i.e. the logic AND of its parents'
permissions. Two guest PxE entries that point at the same table gfn need to
be shadowed with different shadow pages if their parents' permissions are
different. KVM currently uses the effective permissions of the last
non-leaf entry for all non-leaf entries. Because all non-leaf SPTEs have
full ("uwx") permissions, and the effective permissions are recorded only
in role.access and merged into the leaves, this can lead to incorrect
reuse of a shadow page and eventually to a missing guest protection page
fault.
For example, here is a shared pagetable:
pgd[] pud[] pmd[] virtual address pointers
/->pmd1(u--)->pte1(uw-)->page1 <- ptr1 (u--)
/->pud1(uw-)--->pmd2(uw-)->pte2(uw-)->page2 <- ptr2 (uw-)
pgd-| (shared pmd[] as above)
\->pud2(u--)--->pmd1(u--)->pte1(uw-)->page1 <- ptr3 (u--)
\->pmd2(uw-)->pte2(uw-)->page2 <- ptr4 (u--)
pud1 and pud2 point to the same pmd table, so:
- ptr1 and ptr3 points to the same page.
- ptr2 and ptr4 points to the same page.
(pud1 and pud2 here are pud entries, while pmd1 and pmd2 here are pmd entries)
- First, the guest reads from ptr1 first and KVM prepares a shadow
page table with role.access=u--, from ptr1's pud1 and ptr1's pmd1.
"u--" comes from the effective permissions of pgd, pud1 and
pmd1, which are stored in pt->access. "u--" is used also to get
the pagetable for pud1, instead of "uw-".
- Then the guest writes to ptr2 and KVM reuses pud1 which is present.
The hypervisor set up a shadow page for ptr2 with pt->access is "uw-"
even though the pud1 pmd (because of the incorrect argument to
kvm_mmu_get_page in the previous step) has role.access="u--".
- Then the guest reads from ptr3. The hypervisor reuses pud1's
shadow pmd for pud2, because both use "u--" for their permissions.
Thus, the shadow pmd already includes entries for both pmd1 and pmd2.
- At last, the guest writes to ptr4. This causes no vmexit or pagefault,
because pud1's shadow page structures included an "uw-" page even though
its role.access was "u--".
Any kind of shared pagetable might have the similar problem when in
virtual machine without TDP enabled if the permissions are different
from different ancestors.
In order to fix the problem, we change pt->access to be an array, and
any access in it will not include permissions ANDed from child ptes.
The test code is: https://lore.kernel.org/kvm/20210603050537.19605-1-jiangshanlai@gmail.com/
Remember to test it with TDP disabled.
The problem had existed long before the commit 41074d07c7 ("KVM: MMU:
Fix inherited permissions for emulated guest pte updates"), and it
is hard to find which is the culprit. So there is no fixes tag here.
Signed-off-by: Lai Jiangshan <laijs@linux.alibaba.com>
Message-Id: <20210603052455.21023-1-jiangshanlai@gmail.com>
Cc: stable@vger.kernel.org
Fixes: cea0f0e7ea ("[PATCH] KVM: MMU: Shadow page table caching")
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Pull KVM fixes from Paolo Bonzini:
"ARM fixes:
- Another state update on exit to userspace fix
- Prevent the creation of mixed 32/64 VMs
- Fix regression with irqbypass not restarting the guest on failed
connect
- Fix regression with debug register decoding resulting in
overlapping access
- Commit exception state on exit to usrspace
- Fix the MMU notifier return values
- Add missing 'static' qualifiers in the new host stage-2 code
x86 fixes:
- fix guest missed wakeup with assigned devices
- fix WARN reported by syzkaller
- do not use BIT() in UAPI headers
- make the kvm_amd.avic parameter bool
PPC fixes:
- make halt polling heuristics consistent with other architectures
selftests:
- various fixes
- new performance selftest memslot_perf_test
- test UFFD minor faults in demand_paging_test"
* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (44 commits)
selftests: kvm: fix overlapping addresses in memslot_perf_test
KVM: X86: Kill off ctxt->ud
KVM: X86: Fix warning caused by stale emulation context
KVM: X86: Use kvm_get_linear_rip() in single-step and #DB/#BP interception
KVM: x86/mmu: Fix comment mentioning skip_4k
KVM: VMX: update vcpu posted-interrupt descriptor when assigning device
KVM: rename KVM_REQ_PENDING_TIMER to KVM_REQ_UNBLOCK
KVM: x86: add start_assignment hook to kvm_x86_ops
KVM: LAPIC: Narrow the timer latency between wait_lapic_expire and world switch
selftests: kvm: do only 1 memslot_perf_test run by default
KVM: X86: Use _BITUL() macro in UAPI headers
KVM: selftests: add shared hugetlbfs backing source type
KVM: selftests: allow using UFFD minor faults for demand paging
KVM: selftests: create alias mappings when using shared memory
KVM: selftests: add shmem backing source type
KVM: selftests: refactor vm_mem_backing_src_type flags
KVM: selftests: allow different backing source types
KVM: selftests: compute correct demand paging size
KVM: selftests: simplify setup_demand_paging error handling
KVM: selftests: Print a message if /dev/kvm is missing
...
KVM_REQ_UNBLOCK will be used to exit a vcpu from
its inner vcpu halt emulation loop.
Rename KVM_REQ_PENDING_TIMER to KVM_REQ_UNBLOCK, switch
PowerPC to arch specific request bit.
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Message-Id: <20210525134321.303768132@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Pull x86 fixes from Borislav Petkov:
"The three SEV commits are not really urgent material. But we figured
since getting them in now will avoid a huge amount of conflicts
between future SEV changes touching tip, the kvm and probably other
trees, sending them to you now would be best.
The idea is that the tip, kvm etc branches for 5.14 will all base
ontop of -rc2 and thus everything will be peachy. What is more, those
changes are purely mechanical and defines movement so they should be
fine to go now (famous last words).
Summary:
- Enable -Wundef for the compressed kernel build stage
- Reorganize SEV code to streamline and simplify future development"
* tag 'x86_urgent_for_v5.13_rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/boot/compressed: Enable -Wundef
x86/msr: Rename MSR_K8_SYSCFG to MSR_AMD64_SYSCFG
x86/sev: Move GHCB MSR protocol and NAE definitions in a common header
x86/sev-es: Rename sev-es.{ch} to sev.{ch}
The capability that exposes new ioctl KVM_X86_SET_MSR_FILTER to
userspace is specified incorrectly as the ioctl itself (instead of
KVM_CAP_X86_MSR_FILTER). This patch fixes it.
Fixes: 1a155254ff ("KVM: x86: Introduce MSR filtering")
Reviewed-by: Alexander Graf <graf@amazon.de>
Signed-off-by: Siddharth Chandrasekaran <sidcha@amazon.de>
Message-Id: <20210503120059.9283-1-sidcha@amazon.de>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Pull kvm updates from Paolo Bonzini:
"This is a large update by KVM standards, including AMD PSP (Platform
Security Processor, aka "AMD Secure Technology") and ARM CoreSight
(debug and trace) changes.
ARM:
- CoreSight: Add support for ETE and TRBE
- Stage-2 isolation for the host kernel when running in protected
mode
- Guest SVE support when running in nVHE mode
- Force W^X hypervisor mappings in nVHE mode
- ITS save/restore for guests using direct injection with GICv4.1
- nVHE panics now produce readable backtraces
- Guest support for PTP using the ptp_kvm driver
- Performance improvements in the S2 fault handler
x86:
- AMD PSP driver changes
- Optimizations and cleanup of nested SVM code
- AMD: Support for virtual SPEC_CTRL
- Optimizations of the new MMU code: fast invalidation, zap under
read lock, enable/disably dirty page logging under read lock
- /dev/kvm API for AMD SEV live migration (guest API coming soon)
- support SEV virtual machines sharing the same encryption context
- support SGX in virtual machines
- add a few more statistics
- improved directed yield heuristics
- Lots and lots of cleanups
Generic:
- Rework of MMU notifier interface, simplifying and optimizing the
architecture-specific code
- a handful of "Get rid of oprofile leftovers" patches
- Some selftests improvements"
* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (379 commits)
KVM: selftests: Speed up set_memory_region_test
selftests: kvm: Fix the check of return value
KVM: x86: Take advantage of kvm_arch_dy_has_pending_interrupt()
KVM: SVM: Skip SEV cache flush if no ASIDs have been used
KVM: SVM: Remove an unnecessary prototype declaration of sev_flush_asids()
KVM: SVM: Drop redundant svm_sev_enabled() helper
KVM: SVM: Move SEV VMCB tracking allocation to sev.c
KVM: SVM: Explicitly check max SEV ASID during sev_hardware_setup()
KVM: SVM: Unconditionally invoke sev_hardware_teardown()
KVM: SVM: Enable SEV/SEV-ES functionality by default (when supported)
KVM: SVM: Condition sev_enabled and sev_es_enabled on CONFIG_KVM_AMD_SEV=y
KVM: SVM: Append "_enabled" to module-scoped SEV/SEV-ES control variables
KVM: SEV: Mask CPUID[0x8000001F].eax according to supported features
KVM: SVM: Move SEV module params/variables to sev.c
KVM: SVM: Disable SEV/SEV-ES if NPT is disabled
KVM: SVM: Free sev_asid_bitmap during init if SEV setup fails
KVM: SVM: Zero out the VMCB array used to track SEV ASID association
x86/sev: Drop redundant and potentially misleading 'sev_enabled'
KVM: x86: Move reverse CPUID helpers to separate header file
KVM: x86: Rename GPR accessors to make mode-aware variants the defaults
...
Pull documentation updates from Jonathan Corbet:
"It's been a relatively busy cycle in docsland, though more than
usually well contained to Documentation/ itself. Highlights include:
- The Chinese translators have been busy and show no signs of
stopping anytime soon. Italian has also caught up.
- Aditya Srivastava has been working on improvements to the
kernel-doc script.
- Thorsten continues his work on reporting-issues.rst and related
documentation around regression reporting.
- Lots of documentation updates, typo fixes, etc. as usual"
* tag 'docs-5.13' of git://git.lwn.net/linux: (139 commits)
docs/zh_CN: add openrisc translation to zh_CN index
docs/zh_CN: add openrisc index.rst translation
docs/zh_CN: add openrisc todo.rst translation
docs/zh_CN: add openrisc openrisc_port.rst translation
docs/zh_CN: add core api translation to zh_CN index
docs/zh_CN: add core-api index.rst translation
docs/zh_CN: add core-api irq index.rst translation
docs/zh_CN: add core-api irq irqflags-tracing.rst translation
docs/zh_CN: add core-api irq irq-domain.rst translation
docs/zh_CN: add core-api irq irq-affinity.rst translation
docs/zh_CN: add core-api irq concepts.rst translation
docs: sphinx-pre-install: don't barf on beta Sphinx releases
scripts: kernel-doc: improve parsing for kernel-doc comments syntax
docs/zh_CN: two minor fixes in zh_CN/doc-guide/
Documentation: dev-tools: Add Testing Overview
docs/zh_CN: add translations in zh_CN/dev-tools/gcov
docs: reporting-issues: make people CC the regressions list
MAINTAINERS: add regressions mailing list
doc:it_IT: align Italian documentation
docs/zh_CN: sync reporting-issues.rst
...
KVM/arm64 updates for Linux 5.13
New features:
- Stage-2 isolation for the host kernel when running in protected mode
- Guest SVE support when running in nVHE mode
- Force W^X hypervisor mappings in nVHE mode
- ITS save/restore for guests using direct injection with GICv4.1
- nVHE panics now produce readable backtraces
- Guest support for PTP using the ptp_kvm driver
- Performance improvements in the S2 fault handler
- Alexandru is now a reviewer (not really a new feature...)
Fixes:
- Proper emulation of the GICR_TYPER register
- Handle the complete set of relocation in the nVHE EL2 object
- Get rid of the oprofile dependency in the PMU code (and of the
oprofile body parts at the same time)
- Debug and SPE fixes
- Fix vcpu reset
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: Nathan Tempelman <natet@google.com>
Message-Id: <20210408223214.2582277-1-natet@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Add a capability, KVM_CAP_SGX_ATTRIBUTE, that can be used by userspace
to grant a VM access to a priveleged attribute, with args[0] holding a
file handle to a valid SGX attribute file.
The SGX subsystem restricts access to a subset of enclave attributes to
provide additional security for an uncompromised kernel, e.g. to prevent
malware from using the PROVISIONKEY to ensure its nodes are running
inside a geniune SGX enclave and/or to obtain a stable fingerprint.
To prevent userspace from circumventing such restrictions by running an
enclave in a VM, KVM restricts guest access to privileged attributes by
default.
Cc: Andy Lutomirski <luto@amacapital.net>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Kai Huang <kai.huang@intel.com>
Message-Id: <0b099d65e933e068e3ea934b0523bab070cb8cea.1618196135.git.kai.huang@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
KVM_CAP_PPC_MULTITCE is a capability, not an ioctl.
Therefore move it from section 4.97 to the new 8.31 (other capabilities).
To fill the gap, move KVM_X86_SET_MSR_FILTER (was 4.126) to
4.97, and shifted Xen-related ioctl (were 4.127 - 4.130) by
one place (4.126 - 4.129).
Also fixed minor typo in KVM_GET_MSR_INDEX_LIST ioctl description
(section 4.3).
Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Message-Id: <20210316170814.64286-1-eesposit@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Although the KVM_ARM_VCPU_INIT documentation mention that the
registers are reset to their "initial values", it doesn't
describe what these values are.
Describe this state explicitly.
Reviewed-by: Alexandru Elisei <alexandru.elisei@arm.com>
Acked-by: Will Deacon <will@kernel.org>
Signed-off-by: Marc Zyngier <maz@kernel.org>
The documentation build legitimately screams about the PTP
documentation table being misformated.
Fix it by adjusting the table width guides.
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Commit 21b6f32f94 ("KVM: arm64: guest debug, define API headers") added
the arm64 KVM_GUESTDBG_USE_HW flag for the KVM_SET_GUEST_DEBUG ioctl and
commit 834bf88726 ("KVM: arm64: enable KVM_CAP_SET_GUEST_DEBUG")
documented and implemented the flag functionality. Since its introduction,
at no point was the flag known by any name other than KVM_GUESTDBG_USE_HW
for the arm64 architecture, so refer to it as such in the documentation.
CC: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Alexandru Elisei <alexandru.elisei@arm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20210407144857.199746-2-alexandru.elisei@arm.com
Before GICv4.1, we don't have direct access to the VLPI state. So
we simply let it fail early when encountering any VLPI in saving.
But now we don't have to return -EACCES directly if on GICv4.1. Let’s
change the hard code and give a chance to save the VLPI state (and
preserve the UAPI).
Signed-off-by: Shenming Lu <lushenming@huawei.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20210322060158.1584-7-lushenming@huawei.com
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: 1a155254ff ("KVM: x86: Introduce MSR filtering")
Cc: stable@vger.kernel.org
Cc: Alexander Graf <graf@amazon.com>
Reported-by: Yuan Yao <yaoyuan0329os@gmail.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210316184436.2544875-2-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Make the location of the HOST_WRITABLE and MMU_WRITABLE configurable for
a given KVM instance. This will allow EPT to use high available bits,
which in turn will free up bit 11 for a constant MMU_PRESENT bit.
No functional change intended.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210225204749.1512652-19-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Rename the various A/D status defines to explicitly associated them with
TDP. There is a subtle dependency on the bits in question never being
set when using PAE paging, as those bits are reserved, not available.
I.e. using these bits outside of TDP (technically EPT) would cause
explosions.
No functional change intended.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210225204749.1512652-13-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Pull KVM fixes from Paolo Bonzini:
"More fixes for ARM and x86"
* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm:
KVM: LAPIC: Advancing the timer expiration on guest initiated write
KVM: x86/mmu: Skip !MMU-present SPTEs when removing SP in exclusive mode
KVM: kvmclock: Fix vCPUs > 64 can't be online/hotpluged
kvm: x86: annotate RCU pointers
KVM: arm64: Fix exclusive limit for IPA size
KVM: arm64: Reject VM creation when the default IPA size is unsupported
KVM: arm64: Ensure I-cache isolation between vcpus of a same VM
KVM: arm64: Don't use cbz/adr with external symbols
KVM: arm64: Fix range alignment when walking page tables
KVM: arm64: Workaround firmware wrongly advertising GICv2-on-v3 compatibility
KVM: arm64: Rename __vgic_v3_get_ich_vtr_el2() to __vgic_v3_get_gic_config()
KVM: arm64: Don't access PMSELR_EL0/PMUSERENR_EL0 when no PMU is available
KVM: arm64: Turn kvm_arm_support_pmu_v3() into a static key
KVM: arm64: Fix nVHE hyp panic host context restore
KVM: arm64: Avoid corrupting vCPU context register in guest exit
KVM: arm64: nvhe: Save the SPE context early
kvm: x86: use NULL instead of using plain integer as pointer
KVM: SVM: Connect 'npt' module param to KVM's internal 'npt_enabled'
KVM: x86: Ensure deadline timer has truly expired before posting its IRQ
