The loop marks vaddr as mapped after incrementing it by page size,
thereby marking the *next* page as mapped. Set the bit in vpages_mapped
first instead.
Fixes: 56fc773203 ("KVM: selftests: Fill in vm->vpages_mapped bitmap in virt_map() too")
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
Message-Id: <20221209015307.1781352-4-oliver.upton@linux.dev>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Currently the ucall MMIO hole is placed immediately after slot0, which
is a relatively safe address in the PA space. However, it is possible
that the same address has already been used for something else (like the
guest program image) in the VA space. At least in my own testing,
building the vgic_irq test with clang leads to the MMIO hole appearing
underneath gicv3_ops.
Stop identity mapping the MMIO hole and instead find an unused VA to map
to it. Yet another subtle detail of the KVM selftests library is that
virt_pg_map() does not update vm->vpages_mapped. Switch over to
virt_map() instead to guarantee that the chosen VA isn't to something
else.
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
Message-Id: <20221209015307.1781352-6-oliver.upton@linux.dev>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Explain the meaning of the bit manipulations of vm_vaddr_populate_bitmap.
These correspond to the "canonical addresses" of x86 and other
architectures, but that is not obvious.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Use a magic value to signal a ucall_alloc() failure instead of simply
doing GUEST_ASSERT(). GUEST_ASSERT() relies on ucall_alloc() and so a
failure puts the guest into an infinite loop.
Use -1 as the magic value, as a real ucall struct should never wrap.
Reported-by: Oliver Upton <oliver.upton@linux.dev>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Fix a == vs. = typo in kvm_get_cpu_address_width() that results in
@pa_bits being left unset if the CPU doesn't support enumerating its
MAX_PHY_ADDR. Flagged by clang's unusued-value warning.
lib/x86_64/processor.c:1034:51: warning: expression result unused [-Wunused-value]
*pa_bits == kvm_cpu_has(X86_FEATURE_PAE) ? 36 : 32;
Fixes: 3bd396353d ("KVM: selftests: Add X86_FEATURE_PAE and use it calc "fallback" MAXPHYADDR")
Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-Id: <20221213001653.3852042-6-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
x86 Xen-for-KVM:
* Allow the Xen runstate information to cross a page boundary
* Allow XEN_RUNSTATE_UPDATE flag behaviour to be configured
* add support for 32-bit guests in SCHEDOP_poll
x86 fixes:
* One-off fixes for various emulation flows (SGX, VMXON, NRIPS=0).
* Reinstate IBPB on emulated VM-Exit that was incorrectly dropped a few
years back when eliminating unnecessary barriers when switching between
vmcs01 and vmcs02.
* Clean up the MSR filter docs.
* Clean up vmread_error_trampoline() to make it more obvious that params
must be passed on the stack, even for x86-64.
* Let userspace set all supported bits in MSR_IA32_FEAT_CTL irrespective
of the current guest CPUID.
* Fudge around a race with TSC refinement that results in KVM incorrectly
thinking a guest needs TSC scaling when running on a CPU with a
constant TSC, but no hardware-enumerated TSC frequency.
* Advertise (on AMD) that the SMM_CTL MSR is not supported
* Remove unnecessary exports
Selftests:
* Fix an inverted check in the access tracking perf test, and restore
support for asserting that there aren't too many idle pages when
running on bare metal.
* Fix an ordering issue in the AMX test introduced by recent conversions
to use kvm_cpu_has(), and harden the code to guard against similar bugs
in the future. Anything that tiggers caching of KVM's supported CPUID,
kvm_cpu_has() in this case, effectively hides opt-in XSAVE features if
the caching occurs before the test opts in via prctl().
* Fix build errors that occur in certain setups (unsure exactly what is
unique about the problematic setup) due to glibc overriding
static_assert() to a variant that requires a custom message.
* Introduce actual atomics for clear/set_bit() in selftests
Documentation:
* Remove deleted ioctls from documentation
* Various fixes
MEM_REGION_TEST_DATA is meant to hold data explicitly used by a
selftest, not implicit allocations due to the selftests infrastructure.
Allocate the ucall pool from MEM_REGION_DATA much like the rest of the
selftests library allocations.
Fixes: 426729b2cf ("KVM: selftests: Add ucall pool based implementation")
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
Message-Id: <20221207214809.489070-5-oliver.upton@linux.dev>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
An interesting feature of the Arm architecture is that the stage-1 MMU
supports two distinct VA regions, controlled by TTBR{0,1}_EL1. As KVM
selftests on arm64 only uses TTBR0_EL1, the VA space is constrained to
[0, 2^(va_bits-1)). This is different from other architectures that
allow for addressing low and high regions of the VA space from a single
page table.
KVM selftests' VA space allocator presumes the valid address range is
split between low and high memory based the MSB, which of course is a
poor match for arm64's TTBR0 region.
Allow architectures to override the default VA space layout. Make use of
the override to align vpages_valid with the behavior of TTBR0 on arm64.
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
Message-Id: <20221207214809.489070-4-oliver.upton@linux.dev>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
KVM/arm64 updates for 6.2
- Enable the per-vcpu dirty-ring tracking mechanism, together with an
option to keep the good old dirty log around for pages that are
dirtied by something other than a vcpu.
- Switch to the relaxed parallel fault handling, using RCU to delay
page table reclaim and giving better performance under load.
- Relax the MTE ABI, allowing a VMM to use the MAP_SHARED mapping
option, which multi-process VMMs such as crosvm rely on.
- Merge the pKVM shadow vcpu state tracking that allows the hypervisor
to have its own view of a vcpu, keeping that state private.
- Add support for the PMUv3p5 architecture revision, bringing support
for 64bit counters on systems that support it, and fix the
no-quite-compliant CHAIN-ed counter support for the machines that
actually exist out there.
- Fix a handful of minor issues around 52bit VA/PA support (64kB pages
only) as a prefix of the oncoming support for 4kB and 16kB pages.
- Add/Enable/Fix a bunch of selftests covering memslots, breakpoints,
stage-2 faults and access tracking. You name it, we got it, we
probably broke it.
- Pick a small set of documentation and spelling fixes, because no
good merge window would be complete without those.
As a side effect, this tag also drags:
- The 'kvmarm-fixes-6.1-3' tag as a dependency to the dirty-ring
series
- A shared branch with the arm64 tree that repaints all the system
registers to match the ARM ARM's naming, and resulting in
interesting conflicts
* kvm-arm64/dirty-ring:
: .
: Add support for the "per-vcpu dirty-ring tracking with a bitmap
: and sprinkles on top", courtesy of Gavin Shan.
:
: This branch drags the kvmarm-fixes-6.1-3 tag which was already
: merged in 6.1-rc4 so that the branch is in a working state.
: .
KVM: Push dirty information unconditionally to backup bitmap
KVM: selftests: Automate choosing dirty ring size in dirty_log_test
KVM: selftests: Clear dirty ring states between two modes in dirty_log_test
KVM: selftests: Use host page size to map ring buffer in dirty_log_test
KVM: arm64: Enable ring-based dirty memory tracking
KVM: Support dirty ring in conjunction with bitmap
KVM: Move declaration of kvm_cpu_dirty_log_size() to kvm_dirty_ring.h
KVM: x86: Introduce KVM_REQ_DIRTY_RING_SOFT_FULL
Signed-off-by: Marc Zyngier <maz@kernel.org>
* kvm-arm64/selftest/access-tracking:
: .
: Small series to add support for arm64 to access_tracking_perf_test and
: correct a couple bugs along the way.
:
: Patches courtesy of Oliver Upton.
: .
KVM: selftests: Build access_tracking_perf_test for arm64
KVM: selftests: Have perf_test_util signal when to stop vCPUs
Signed-off-by: Marc Zyngier <maz@kernel.org>
* kvm-arm64/selftest/s2-faults:
: .
: New KVM/arm64 selftests exercising various sorts of S2 faults, courtesy
: of Ricardo Koller. From the cover letter:
:
: "This series adds a new aarch64 selftest for testing stage 2 fault handling
: for various combinations of guest accesses (e.g., write, S1PTW), backing
: sources (e.g., anon), and types of faults (e.g., read on hugetlbfs with a
: hole, write on a readonly memslot). Each test tries a different combination
: and then checks that the access results in the right behavior (e.g., uffd
: faults with the right address and write/read flag). [...]"
: .
KVM: selftests: aarch64: Add mix of tests into page_fault_test
KVM: selftests: aarch64: Add readonly memslot tests into page_fault_test
KVM: selftests: aarch64: Add dirty logging tests into page_fault_test
KVM: selftests: aarch64: Add userfaultfd tests into page_fault_test
KVM: selftests: aarch64: Add aarch64/page_fault_test
KVM: selftests: Use the right memslot for code, page-tables, and data allocations
KVM: selftests: Fix alignment in virt_arch_pgd_alloc() and vm_vaddr_alloc()
KVM: selftests: Add vm->memslots[] and enum kvm_mem_region_type
KVM: selftests: Stash backing_src_type in struct userspace_mem_region
tools: Copy bitfield.h from the kernel sources
KVM: selftests: aarch64: Construct DEFAULT_MAIR_EL1 using sysreg.h macros
KVM: selftests: Add missing close and munmap in __vm_mem_region_delete()
KVM: selftests: aarch64: Add virt_get_pte_hva() library function
KVM: selftests: Add a userfaultfd library
Signed-off-by: Marc Zyngier <maz@kernel.org>
Drop the "atomic_" prefix from tools' atomic_test_and_set_bit() to
match the kernel nomenclature where test_and_set_bit() is atomic,
and __test_and_set_bit() provides the non-atomic variant.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20221119013450.2643007-9-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Disallow using kvm_get_supported_cpuid() and thus caching KVM's supported
CPUID info before enabling XSAVE-managed features that are off-by-default
and must be enabled by ARCH_REQ_XCOMP_GUEST_PERM. Caching the supported
CPUID before all XSAVE features are enabled can result in false negatives
due to testing features that were cached before they were enabled.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Link: https://lore.kernel.org/r/20221128225735.3291648-4-seanjc@google.com
Move __vm_xsave_require_permission() below the CPUID helpers so that a
future change can reference the cached result of KVM_GET_SUPPORTED_CPUID
while keeping the definition of the variable close to its intended user,
kvm_get_supported_cpuid().
No functional change intended.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Link: https://lore.kernel.org/r/20221128225735.3291648-3-seanjc@google.com
Move the kvm_cpu_has() check on X86_FEATURE_XFD out of the helper to
enable off-by-default XSAVE-managed features and into the one test that
currenty requires XFD (XFeature Disable) support. kvm_cpu_has() uses
kvm_get_supported_cpuid() and thus caches KVM_GET_SUPPORTED_CPUID, and so
using kvm_cpu_has() before ARCH_REQ_XCOMP_GUEST_PERM effectively results
in the test caching stale values, e.g. subsequent checks on AMX_TILE will
get false negatives.
Although off-by-default features are nonsensical without XFD, checking
for XFD virtualization prior to enabling such features isn't strictly
required.
Signed-off-by: Lei Wang <lei4.wang@intel.com>
Fixes: 7fbb653e01 ("KVM: selftests: Check KVM's supported CPUID, not host CPUID, for XFD")
Link: https://lore.kernel.org/r/20221125023839.315207-1-lei4.wang@intel.com
[sean: add Fixes, reword changelog]
Signed-off-by: Sean Christopherson <seanjc@google.com>
Link: https://lore.kernel.org/r/20221128225735.3291648-2-seanjc@google.com
Signal that a test run is complete through perf_test_args instead of
having tests open code a similar solution. Ensure that the field resets
to false at the beginning of a test run as the structure is reused
between test runs, eliminating a couple of bugs:
access_tracking_perf_test hangs indefinitely on a subsequent test run,
as 'done' remains true. The bug doesn't amount to much right now, as x86
supports a single guest mode. However, this is a precondition of
enabling the test for other architectures with >1 guest mode, like
arm64.
memslot_modification_stress_test has the exact opposite problem, where
subsequent test runs complete immediately as 'run_vcpus' remains false.
Co-developed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
[oliver: added commit message, preserve spin_wait_for_next_iteration()]
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
Reviewed-by: Gavin Shan <gshan@redhat.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20221118211503.4049023-2-oliver.upton@linux.dev
There's no need to pollute VMX and SVM code with Hyper-V specific
stuff and allocate Hyper-V specific test pages for all test as only
few really need them. Create a dedicated struct and an allocation
helper.
Reviewed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20221101145426.251680-43-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
In preparation to putting Hyper-V specific test pages to a dedicated
struct, move eVMCS load logic from load_vmcs(). Tests call load_vmcs()
directly and the only one which needs 'enlightened' version is
evmcs_test so there's not much gain in having this merged.
Temporary pass both GPA and HVA to load_evmcs().
Reviewed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20221101145426.251680-42-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Currently, tests can only request a new vaddr range by using
vm_vaddr_alloc()/vm_vaddr_alloc_page()/vm_vaddr_alloc_pages() but
these functions allocate and map physical pages too. Make it possible
to request unmapped range too.
Reviewed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20221101145426.251680-36-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This fixes three issues in nested SVM:
1) in the shutdown_interception() vmexit handler we call kvm_vcpu_reset().
However, if running nested and L1 doesn't intercept shutdown, the function
resets vcpu->arch.hflags without properly leaving the nested state.
This leaves the vCPU in inconsistent state and later triggers a kernel
panic in SVM code. The same bug can likely be triggered by sending INIT
via local apic to a vCPU which runs a nested guest.
On VMX we are lucky that the issue can't happen because VMX always
intercepts triple faults, thus triple fault in L2 will always be
redirected to L1. Plus, handle_triple_fault() doesn't reset the vCPU.
INIT IPI can't happen on VMX either because INIT events are masked while
in VMX mode.
Secondarily, KVM doesn't honour SHUTDOWN intercept bit of L1 on SVM.
A normal hypervisor should always intercept SHUTDOWN, a unit test on
the other hand might want to not do so.
Finally, the guest can trigger a kernel non rate limited printk on SVM
from the guest, which is fixed as well.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Now that a VM isn't needed to check for nEPT support, assert that KVM
supports nEPT in prepare_eptp() instead of skipping the test, and push
the TEST_REQUIRE() check out to individual tests. The require+assert are
somewhat redundant and will incur some amount of ongoing maintenance
burden, but placing the "require" logic in the test makes it easier to
find/understand a test's requirements and in this case, provides a very
strong hint that the test cares about nEPT.
Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: David Matlack <dmatlack@google.com>
Link: https://lore.kernel.org/r/20220927165209.930904-1-dmatlack@google.com
[sean: rebase on merged code, write changelog]
Signed-off-by: Sean Christopherson <seanjc@google.com>
When checking for nEPT support in KVM, use kvm_get_feature_msr() instead
of vcpu_get_msr() to retrieve KVM's default TRUE_PROCBASED_CTLS and
PROCBASED_CTLS2 MSR values, i.e. don't require a VM+vCPU to query nEPT
support.
Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: David Matlack <dmatlack@google.com>
Link: https://lore.kernel.org/r/20220927165209.930904-1-dmatlack@google.com
[sean: rebase on merged code, write changelog]
Signed-off-by: Sean Christopherson <seanjc@google.com>
Add dedicated helpers for getting x86's Family and Model, which are the
last holdouts that "need" raw access to CPUID information. FMS info is
a mess and requires not only splicing together multiple values, but
requires doing so conditional in the Family case.
Provide wrappers to reduce the odds of copy+paste errors, but mostly to
allow for the eventual removal of kvm_get_supported_cpuid_entry().
No functional change intended.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Link: https://lore.kernel.org/r/20221006005125.680782-11-seanjc@google.com
Introduce X86_PROPERTY_* to allow retrieving values/properties from CPUID
leafs, e.g. MAXPHYADDR from CPUID.0x80000008. Use the same core code as
X86_FEATURE_*, the primary difference is that properties are multi-bit
values, whereas features enumerate a single bit.
Add this_cpu_has_p() to allow querying whether or not a property exists
based on the maximum leaf associated with the property, e.g. MAXPHYADDR
doesn't exist if the max leaf for 0x8000_xxxx is less than 0x8000_0008.
Use the new property infrastructure in vm_compute_max_gfn() to prove
that the code works as intended. Future patches will convert additional
selftests code.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Link: https://lore.kernel.org/r/20221006005125.680782-4-seanjc@google.com
Provide the error code on a fault in KVM_ASM_SAFE(), e.g. to allow tests
to assert that #PF generates the correct error code without needing to
manually install a #PF handler. Use r10 as the scratch register for the
error code, as it's already clobbered by the asm blob (loaded with the
RIP of the to-be-executed instruction). Deliberately load the output
"error_code" even in the non-faulting path so that error_code is always
initialized with deterministic data (the aforementioned RIP), i.e to
ensure a selftest won't end up with uninitialized consumption regardless
of how KVM_ASM_SAFE() is used.
Don't clear r10 in the non-faulting case and instead load error code with
the RIP (see above). The error code is valid if and only if an exception
occurs, and '0' isn't necessarily a better "invalid" value, e.g. '0'
could result in false passes for a buggy test.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: David Matlack <dmatlack@google.com>
Link: https://lore.kernel.org/r/20221102184654.282799-9-dmatlack@google.com
Play nice with huge pages when getting PTEs and translating GVAs to GPAs,
there's no reason to disallow using huge pages in selftests. Use
PG_LEVEL_NONE to indicate that the caller doesn't care about the mapping
level and just wants to get the pte+level.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Link: https://lore.kernel.org/r/20221006004512.666529-8-seanjc@google.com
Remove the pointless shift from GPA=>GFN and immediately back to
GFN=>GPA when creating guest page tables. Ignore the other walkers
that have a similar pattern for the moment, they will be converted
to use virt_get_pte() in the near future.
No functional change intended.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Link: https://lore.kernel.org/r/20221006004512.666529-4-seanjc@google.com
Drop the reserved bit checks from the helper to retrieve a PTE, there's
very little value in sanity checking the constructed page tables as any
will quickly be noticed in the form of an unexpected #PF. The checks
also place unnecessary restrictions on the usage of the helpers, e.g. if
a test _wanted_ to set reserved bits for whatever reason.
Removing the NX check in particular allows for the removal of the @vcpu
param, which will in turn allow the helper to be reused nearly verbatim
for addr_gva2gpa().
Signed-off-by: Sean Christopherson <seanjc@google.com>
Link: https://lore.kernel.org/r/20221006004512.666529-3-seanjc@google.com
Drop vm_{g,s}et_page_table_entry() and instead expose the "inner"
helper (was _vm_get_page_table_entry()) that returns a _pointer_ to the
PTE, i.e. let tests directly modify PTEs instead of bouncing through
helpers that just make life difficult.
Opportunsitically use BIT_ULL() in emulator_error_test, and use the
MAXPHYADDR define to set the "rogue" GPA bit instead of open coding the
same value.
No functional change intended.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Link: https://lore.kernel.org/r/20221006004512.666529-2-seanjc@google.com
To play nice with guests whose stack memory is encrypted, e.g. AMD SEV,
introduce a new "ucall pool" implementation that passes the ucall struct
via dedicated memory (which can be mapped shared, a.k.a. as plain text).
Because not all architectures have access to the vCPU index in the guest,
use a bitmap with atomic accesses to track which entries in the pool are
free/used. A list+lock could also work in theory, but synchronizing the
individual pointers to the guest would be a mess.
Note, there's no need to rewalk the bitmap to ensure success. If all
vCPUs are simply allocating, success is guaranteed because there are
enough entries for all vCPUs. If one or more vCPUs are freeing and then
reallocating, success is guaranteed because vCPUs _always_ walk the
bitmap from 0=>N; if vCPU frees an entry and then wins a race to
re-allocate, then either it will consume the entry it just freed (bit is
the first free bit), or the losing vCPU is guaranteed to see the freed
bit (winner consumes an earlier bit, which the loser hasn't yet visited).
Reviewed-by: Andrew Jones <andrew.jones@linux.dev>
Signed-off-by: Peter Gonda <pgonda@google.com>
Co-developed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Link: https://lore.kernel.org/r/20221006003409.649993-8-seanjc@google.com
Drop ucall_uninit() and ucall_arch_uninit() now that ARM doesn't modify
the host's copy of ucall_exit_mmio_addr, i.e. now that there's no need to
reset the pointer before potentially creating a new VM. The few calls to
ucall_uninit() are all immediately followed by kvm_vm_free(), and that is
likely always going to hold true, i.e. it's extremely unlikely a test
will want to effectively disable ucall in the middle of a test.
Reviewed-by: Andrew Jones <andrew.jones@linux.dev>
Tested-by: Peter Gonda <pgonda@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Link: https://lore.kernel.org/r/20221006003409.649993-7-seanjc@google.com
Fix a mostly-theoretical bug where ARM's ucall MMIO setup could result in
different VMs stomping on each other by cloberring the global pointer.
Fix the most obvious issue by saving the MMIO gpa into the VM.
A more subtle bug is that creating VMs in parallel (on multiple tasks)
could result in a VM using the wrong address. Synchronizing a global to
a guest effectively snapshots the value on a per-VM basis, i.e. the
"global" is already prepped to work with multiple VMs, but setting the
global in the host is not thread-safe. To fix that bug, add
write_guest_global() to allow stuffing a VM's copy of a "global" without
modifying the host value.
Reviewed-by: Andrew Jones <andrew.jones@linux.dev>
Tested-by: Peter Gonda <pgonda@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Link: https://lore.kernel.org/r/20221006003409.649993-6-seanjc@google.com
Do init_ucall() automatically during VM creation to kill two (three?)
birds with one stone.
First, initializing ucall immediately after VM creations allows forcing
aarch64's MMIO ucall address to immediately follow memslot0. This is
still somewhat fragile as tests could clobber the MMIO address with a
new memslot, but it's safe-ish since tests have to be conversative when
accounting for memslot0. And this can be hardened in the future by
creating a read-only memslot for the MMIO page (KVM ARM exits with MMIO
if the guest writes to a read-only memslot). Add a TODO to document that
selftests can and should use a memslot for the ucall MMIO (doing so
requires yet more rework because tests assumes thay can use all memslots
except memslot0).
Second, initializing ucall for all VMs prepares for making ucall
initialization meaningful on all architectures. aarch64 is currently the
only arch that needs to do any setup, but that will change in the future
by switching to a pool-based implementation (instead of the current
stack-based approach).
Lastly, defining the ucall MMIO address from common code will simplify
switching all architectures (except s390) to a common MMIO-based ucall
implementation (if there's ever sufficient motivation to do so).
Cc: Oliver Upton <oliver.upton@linux.dev>
Reviewed-by: Andrew Jones <andrew.jones@linux.dev>
Tested-by: Peter Gonda <pgonda@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Link: https://lore.kernel.org/r/20221006003409.649993-4-seanjc@google.com
Consolidate the actual copying of a ucall struct from guest=>host into
the common get_ucall(). Return a host virtual address instead of a guest
virtual address even though the addr_gva2hva() part could be moved to
get_ucall() too. Conceptually, get_ucall() is invoked from the host and
should return a host virtual address (and returning NULL for "nothing to
see here" is far superior to returning 0).
Use pointer shenanigans instead of an unnecessary bounce buffer when the
caller of get_ucall() provides a valid pointer.
Reviewed-by: Andrew Jones <andrew.jones@linux.dev>
Tested-by: Peter Gonda <pgonda@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Link: https://lore.kernel.org/r/20221006003409.649993-3-seanjc@google.com
Make ucall() a common helper that populates struct ucall, and only calls
into arch code to make the actually call out to userspace.
Rename all arch-specific helpers to make it clear they're arch-specific,
and to avoid collisions with common helpers (one more on its way...)
Add WRITE_ONCE() to stores in ucall() code (as already done to aarch64
code in commit 9e2f6498ef ("selftests: KVM: Handle compiler
optimizations in ucall")) to prevent clang optimizations breaking ucalls.
Cc: Colton Lewis <coltonlewis@google.com>
Reviewed-by: Andrew Jones <andrew.jones@linux.dev>
Tested-by: Peter Gonda <pgonda@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Link: https://lore.kernel.org/r/20221006003409.649993-2-seanjc@google.com
