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Bus lock debug exception introduces a new bit DR6_BUS_LOCK (bit 11 of
DR6) to indicate that bus lock #DB exception is generated. The set/clear
of DR6_BUS_LOCK is similar to the DR6_RTM. The processor clears
DR6_BUS_LOCK when the exception is generated. For all other #DB, the
processor sets this bit to 1. Software #DB handler should set this bit
before returning to the interrupted task.
In VMM, to avoid breaking the CPUs without bus lock #DB exception
support, activate the DR6_BUS_LOCK conditionally in DR6_FIXED_1 bits.
When intercepting the #DB exception caused by bus locks, bit 11 of the
exit qualification is set to identify it. The VMM should emulate the
exception by clearing the bit 11 of the guest DR6.
Co-developed-by: Xiaoyao Li <xiaoyao.li@intel.com>
Signed-off-by: Xiaoyao Li <xiaoyao.li@intel.com>
Signed-off-by: Chenyi Qiang <chenyi.qiang@intel.com>
Message-Id: <20210202090433.13441-3-chenyi.qiang@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Commit b1c5356e873c ("KVM: PPC: Convert to the gfn-based MMU notifier
callbacks") causes unmap_gfn_range and age_gfn callbacks to only work
on the first gfn in the range. It also makes the aging callbacks call
into both radix and hash aging functions for radix guests. Fix this.
Add warnings for the single-gfn calls that have been converted to range
callbacks, in case they ever receieve ranges greater than 1.
Fixes: b1c5356e873c ("KVM: PPC: Convert to the gfn-based MMU notifier callbacks")
Reported-by: Bharata B Rao <bharata@linux.ibm.com>
Tested-by: Bharata B Rao <bharata@linux.ibm.com>
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Message-Id: <20210505121509.1470207-1-npiggin@gmail.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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If probing MSR_TSC_AUX failed, hide RDTSCP and RDPID, and WARN if either
feature was reported as supported. In theory, such a scenario should
never happen as both Intel and AMD state that MSR_TSC_AUX is available if
RDTSCP or RDPID is supported. But, KVM injects #GP on MSR_TSC_AUX
accesses if probing failed, faults on WRMSR(MSR_TSC_AUX) may be fatal to
the guest (because they happen during early CPU bringup), and KVM itself
has effectively misreported RDPID support in the past.
Note, this also has the happy side effect of omitting MSR_TSC_AUX from
the list of MSRs that are exposed to userspace if probing the MSR fails.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210504171734.1434054-16-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Squish the Intel and AMD emulation of MSR_TSC_AUX together and tie it to
the guest CPU model instead of the host CPU behavior. While not strictly
necessary to avoid guest breakage, emulating cross-vendor "architecture"
will provide consistent behavior for the guest, e.g. WRMSR fault behavior
won't change if the vCPU is migrated to a host with divergent behavior.
Note, the "new" kvm_is_supported_user_return_msr() checks do not add new
functionality on either SVM or VMX. On SVM, the equivalent was
"tsc_aux_uret_slot < 0", and on VMX the check was buried in the
vmx_find_uret_msr() call at the find_uret_msr label.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210504171734.1434054-15-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Now that SVM and VMX both probe MSRs before "defining" user return slots
for them, consolidate the code for probe+define into common x86 and
eliminate the odd behavior of having the vendor code define the slot for
a given MSR.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210504171734.1434054-14-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Split out and export the number of configured user return MSRs so that
VMX can iterate over the set of MSRs without having to do its own tracking.
Keep the list itself internal to x86 so that vendor code still has to go
through the "official" APIs to add/modify entries.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210504171734.1434054-13-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Tag TSX_CTRL as not needing to be loaded when RTM isn't supported in the
host. Crushing the write mask to '0' has the same effect, but requires
more mental gymnastics to understand.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210504171734.1434054-12-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Drop VMX's global list of user return MSRs now that VMX doesn't resort said
list to isolate "active" MSRs, i.e. now that VMX's list and x86's list have
the same MSRs in the same order.
In addition to eliminating the redundant list, this will also allow moving
more of the list management into common x86.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210504171734.1434054-11-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Explicitly flag a uret MSR as needing to be loaded into hardware instead of
resorting the list of "active" MSRs and tracking how many MSRs in total
need to be loaded. The only benefit to sorting the list is that the loop
to load MSRs during vmx_prepare_switch_to_guest() doesn't need to iterate
over all supported uret MRS, only those that are active. But that is a
pointless optimization, as the most common case, running a 64-bit guest,
will load the vast majority of MSRs. Not to mention that a single WRMSR is
far more expensive than iterating over the list.
Providing a stable list order obviates the need to track a given MSR's
"slot" in the per-CPU list of user return MSRs; all lists simply use the
same ordering. Future patches will take advantage of the stable order to
further simplify the related code.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210504171734.1434054-10-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Configure the list of user return MSRs that are actually supported at
module init instead of reprobing the list of possible MSRs every time a
vCPU is created. Curating the list on a per-vCPU basis is pointless; KVM
is completely hosed if the set of supported MSRs changes after module init,
or if the set of MSRs differs per physical PCU.
The per-vCPU lists also increase complexity (see __vmx_find_uret_msr()) and
creates corner cases that _should_ be impossible, but theoretically exist
in KVM, e.g. advertising RDTSCP to userspace without actually being able to
virtualize RDTSCP if probing MSR_TSC_AUX fails.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210504171734.1434054-9-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Allow userspace to enable RDPID for a guest without also enabling RDTSCP.
Aside from checking for RDPID support in the obvious flows, VMX also needs
to set ENABLE_RDTSCP=1 when RDPID is exposed.
For the record, there is no known scenario where enabling RDPID without
RDTSCP is desirable. But, both AMD and Intel architectures allow for the
condition, i.e. this is purely to make KVM more architecturally accurate.
Fixes: 41cd02c6f7f6 ("kvm: x86: Expose RDPID in KVM_GET_SUPPORTED_CPUID")
Cc: stable@vger.kernel.org
Reported-by: Reiji Watanabe <reijiw@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210504171734.1434054-8-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Probe MSR_TSC_AUX whether or not RDTSCP is supported in the host, and
if probing succeeds, load the guest's MSR_TSC_AUX into hardware prior to
VMRUN. Because SVM doesn't support interception of RDPID, RDPID cannot
be disallowed in the guest (without resorting to binary translation).
Leaving the host's MSR_TSC_AUX in hardware would leak the host's value to
the guest if RDTSCP is not supported.
Note, there is also a kernel bug that prevents leaking the host's value.
The host kernel initializes MSR_TSC_AUX if and only if RDTSCP is
supported, even though the vDSO usage consumes MSR_TSC_AUX via RDPID.
I.e. if RDTSCP is not supported, there is no host value to leak. But,
if/when the host kernel bug is fixed, KVM would start leaking MSR_TSC_AUX
in the case where hardware supports RDPID but RDTSCP is unavailable for
whatever reason.
Probing MSR_TSC_AUX will also allow consolidating the probe and define
logic in common x86, and will make it simpler to condition the existence
of MSR_TSX_AUX (from the guest's perspective) on RDTSCP *or* RDPID.
Cc: stable@vger.kernel.org
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210504171734.1434054-7-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Disable preemption when probing a user return MSR via RDSMR/WRMSR. If
the MSR holds a different value per logical CPU, the WRMSR could corrupt
the host's value if KVM is preempted between the RDMSR and WRMSR, and
then rescheduled on a different CPU.
Opportunistically land the helper in common x86, SVM will use the helper
in a future commit.
Fixes: 4be534102624 ("KVM: VMX: Initialize vmx->guest_msrs[] right after allocation")
Cc: stable@vger.kernel.org
Cc: Xiaoyao Li <xiaoyao.li@intel.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210504171734.1434054-6-seanjc@google.com>
Reviewed-by: Jim Mattson <jmattson@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Add a dedicated intercept enum for RDPID instead of piggybacking RDTSCP.
Unlike VMX's ENABLE_RDTSCP, RDPID is not bound to SVM's RDTSCP intercept.
Fixes: fb6d4d340e05 ("KVM: x86: emulate RDPID")
Cc: stable@vger.kernel.org
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210504171734.1434054-5-seanjc@google.com>
Reviewed-by: Jim Mattson <jmattson@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Intercept RDTSCP to inject #UD if RDTSC is disabled in the guest.
Note, SVM does not support intercepting RDPID. Unlike VMX's
ENABLE_RDTSCP control, RDTSCP interception does not apply to RDPID. This
is a benign virtualization hole as the host kernel (incorrectly) sets
MSR_TSC_AUX if RDTSCP is supported, and KVM loads the guest's MSR_TSC_AUX
into hardware if RDTSCP is supported in the host, i.e. KVM will not leak
the host's MSR_TSC_AUX to the guest.
But, when the kernel bug is fixed, KVM will start leaking the host's
MSR_TSC_AUX if RDPID is supported in hardware, but RDTSCP isn't available
for whatever reason. This leak will be remedied in a future commit.
Fixes: 46896c73c1a4 ("KVM: svm: add support for RDTSCP")
Cc: stable@vger.kernel.org
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210504171734.1434054-4-seanjc@google.com>
Reviewed-by: Jim Mattson <jmattson@google.com>
Reviewed-by: Reiji Watanabe <reijiw@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Do not advertise emulation support for RDPID if RDTSCP is unsupported.
RDPID emulation subtly relies on MSR_TSC_AUX to exist in hardware, as
both vmx_get_msr() and svm_get_msr() will return an error if the MSR is
unsupported, i.e. ctxt->ops->get_msr() will fail and the emulator will
inject a #UD.
Note, RDPID emulation also relies on RDTSCP being enabled in the guest,
but this is a KVM bug and will eventually be fixed.
Fixes: fb6d4d340e05 ("KVM: x86: emulate RDPID")
Cc: stable@vger.kernel.org
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210504171734.1434054-3-seanjc@google.com>
Reviewed-by: Jim Mattson <jmattson@google.com>
Reviewed-by: Reiji Watanabe <reijiw@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Clear KVM's RDPID capability if the ENABLE_RDTSCP secondary exec control is
unsupported. Despite being enumerated in a separate CPUID flag, RDPID is
bundled under the same VMCS control as RDTSCP and will #UD in VMX non-root
if ENABLE_RDTSCP is not enabled.
Fixes: 41cd02c6f7f6 ("kvm: x86: Expose RDPID in KVM_GET_SUPPORTED_CPUID")
Cc: stable@vger.kernel.org
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210504171734.1434054-2-seanjc@google.com>
Reviewed-by: Jim Mattson <jmattson@google.com>
Reviewed-by: Reiji Watanabe <reijiw@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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While in most cases, when returning to use the VMCB01,
the exit reason stored in it will be SVM_EXIT_VMRUN,
on first VM exit after a nested migration this field
can contain anything since the VM entry did happen
before the migration.
Remove this warning to avoid the false positive.
Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Message-Id: <20210504143936.1644378-3-mlevitsk@redhat.com>
Fixes: 9a7de6ecc3ed ("KVM: nSVM: If VMRUN is single-stepped, queue the #DB intercept in nested_svm_vmexit()")
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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While usually the L1's GIF is set while L2 runs, and usually
migration nested state is loaded after a vCPU reset which
also sets L1's GIF to true, this is not guaranteed.
Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Message-Id: <20210504143936.1644378-2-mlevitsk@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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In ioctl KVM_X86_SET_MSR_FILTER, input from user space is validated
after a memdup_user(). For invalid inputs we'd memdup and then call
kfree unnecessarily. Hoist input validation to avoid kfree altogether.
Signed-off-by: Siddharth Chandrasekaran <sidcha@amazon.de>
Message-Id: <20210503122111.13775-1-sidcha@amazon.de>
Reviewed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Clang's integrated assembler does not allow symbols with non-absolute
values to be reassigned. Modify the interrupt entry loop macro to be
compatible with IAS by using a label and an offset.
Cc: Jian Cai <caij2003@gmail.com>
Signed-off-by: Bill Wendling <morbo@google.com>
References: https://lore.kernel.org/lkml/20200714233024.1789985-1-caij2003@gmail.com/
Message-Id: <20201211012317.3722214-1-morbo@google.com>
Reviewed-by: Jim Mattson <jmattson@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Eliminate the probably unwanted hole in 'struct kvm_vmx_nested_state_hdr':
Pre-patch:
struct kvm_vmx_nested_state_hdr {
__u64 vmxon_pa; /* 0 8 */
__u64 vmcs12_pa; /* 8 8 */
struct {
__u16 flags; /* 16 2 */
} smm; /* 16 2 */
/* XXX 2 bytes hole, try to pack */
__u32 flags; /* 20 4 */
__u64 preemption_timer_deadline; /* 24 8 */
};
Post-patch:
struct kvm_vmx_nested_state_hdr {
__u64 vmxon_pa; /* 0 8 */
__u64 vmcs12_pa; /* 8 8 */
struct {
__u16 flags; /* 16 2 */
} smm; /* 16 2 */
__u16 pad; /* 18 2 */
__u32 flags; /* 20 4 */
__u64 preemption_timer_deadline; /* 24 8 */
};
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20210503150854.1144255-3-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Add a test for the regression, introduced by commit f2c7ef3ba955
("KVM: nSVM: cancel KVM_REQ_GET_NESTED_STATE_PAGES on nested vmexit"). When
L2->L1 exit is forced immediately after restoring nested state,
KVM_REQ_GET_NESTED_STATE_PAGES request is cleared and VMCS12 changes
(e.g. fresh RIP) are not reflected to eVMCS. The consequent nested
vCPU run gets broken.
Utilize NMI injection to do the job.
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20210505151823.1341678-3-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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'run->exit_reason == KVM_EXIT_SHUTDOWN' check is not ideal as we may be
getting some unexpected exception. Directly check for #UD instead.
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20210505151823.1341678-2-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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When enlightened VMCS is in use and nested state is migrated with
vmx_get_nested_state()/vmx_set_nested_state() KVM can't map evmcs
page right away: evmcs gpa is not 'struct kvm_vmx_nested_state_hdr'
and we can't read it from VP assist page because userspace may decide
to restore HV_X64_MSR_VP_ASSIST_PAGE after restoring nested state
(and QEMU, for example, does exactly that). To make sure eVMCS is
mapped /vmx_set_nested_state() raises KVM_REQ_GET_NESTED_STATE_PAGES
request.
Commit f2c7ef3ba955 ("KVM: nSVM: cancel KVM_REQ_GET_NESTED_STATE_PAGES
on nested vmexit") added KVM_REQ_GET_NESTED_STATE_PAGES clearing to
nested_vmx_vmexit() to make sure MSR permission bitmap is not switched
when an immediate exit from L2 to L1 happens right after migration (caused
by a pending event, for example). Unfortunately, in the exact same
situation we still need to have eVMCS mapped so
nested_sync_vmcs12_to_shadow() reflects changes in VMCS12 to eVMCS.
As a band-aid, restore nested_get_evmcs_page() when clearing
KVM_REQ_GET_NESTED_STATE_PAGES in nested_vmx_vmexit(). The 'fix' is far
from being ideal as we can't easily propagate possible failures and even if
we could, this is most likely already too late to do so. The whole
'KVM_REQ_GET_NESTED_STATE_PAGES' idea for mapping eVMCS after migration
seems to be fragile as we diverge too much from the 'native' path when
vmptr loading happens on vmx_set_nested_state().
Fixes: f2c7ef3ba955 ("KVM: nSVM: cancel KVM_REQ_GET_NESTED_STATE_PAGES on nested vmexit")
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20210503150854.1144255-2-vkuznets@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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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: 1a155254ff93 ("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>
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Simplify the code by making PV features shutdown happen in one place.
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20210414123544.1060604-6-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Crash shutdown handler only disables kvmclock and steal time, other PV
features remain active so we risk corrupting memory or getting some
side-effects in kdump kernel. Move crash handler to kvm.c and unify
with CPU offline.
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20210414123544.1060604-5-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Currenly, we disable kvmclock from machine_shutdown() hook and this
only happens for boot CPU. We need to disable it for all CPUs to
guard against memory corruption e.g. on restore from hibernate.
Note, writing '0' to kvmclock MSR doesn't clear memory location, it
just prevents hypervisor from updating the location so for the short
while after write and while CPU is still alive, the clock remains usable
and correct so we don't need to switch to some other clocksource.
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20210414123544.1060604-4-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Various PV features (Async PF, PV EOI, steal time) work through memory
shared with hypervisor and when we restore from hibernation we must
properly teardown all these features to make sure hypervisor doesn't
write to stale locations after we jump to the previously hibernated kernel
(which can try to place anything there). For secondary CPUs the job is
already done by kvm_cpu_down_prepare(), register syscore ops to do
the same for boot CPU.
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20210414123544.1060604-3-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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'pr_fmt' already has 'kvm-guest: ' so 'KVM' prefix is redundant.
"Unregister pv shared memory" is very ambiguous, it's hard to
say which particular PV feature it relates to.
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20210414123544.1060604-2-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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The fget can potentially return null, so the fput on the error return
path can cause a null pointer dereference. Fix this by checking for
a null source_kvm_file before doing a fput.
Addresses-Coverity: ("Dereference null return")
Fixes: 54526d1fd593 ("KVM: x86: Support KVM VMs sharing SEV context")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Message-Id: <20210430170303.131924-1-colin.king@canonical.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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The function name of kdoc of __handle_changed_spte() should be itself,
rather than handle_changed_spte(). Fix the typo.
Signed-off-by: Kai Huang <kai.huang@intel.com>
Message-Id: <20210503042446.154695-1-kai.huang@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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This allows the KVM to load the nested state more than
once without warnings.
Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Message-Id: <20210503125446.1353307-4-mlevitsk@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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* 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: 4995a3685f1b ("KVM: SVM: Use a separate vmcb for the nested L2 guest")
Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Message-Id: <20210503125446.1353307-3-mlevitsk@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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When forcibly leaving the nested mode, we should switch to vmcb01
Fixes: 4995a3685f1b ("KVM: SVM: Use a separate vmcb for the nested L2 guest")
Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Message-Id: <20210503125446.1353307-2-mlevitsk@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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single_task_running() is usually more general than need_resched()
but CFS_BANDWIDTH throttling will use resched_task() when there
is just one task to get the task to block. This was causing
long-need_resched warnings and was likely allowing VMs to
overrun their quota when halt polling.
Signed-off-by: Ben Segall <bsegall@google.com>
Signed-off-by: Venkatesh Srinivas <venkateshs@chromium.org>
Message-Id: <20210429162233.116849-1-venkateshs@chromium.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Cc: stable@vger.kernel.org
Reviewed-by: Jim Mattson <jmattson@google.com>
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Commit ee66e453db13d (KVM: lapic: Busy wait for timer to expire when
using hv_timer) tries to set ktime->expired_tscdeadline by checking
ktime->hv_timer_in_use since lapic timer oneshot/periodic modes which
are emulated by vmx preemption timer also get advanced, they leverage
the same vmx preemption timer logic with tsc-deadline mode. However,
ktime->hv_timer_in_use is cleared before apic_timer_expired() handling,
let's delay this clearing in preemption-disabled region.
Fixes: ee66e453db13d ("KVM: lapic: Busy wait for timer to expire when using hv_timer")
Reviewed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
Message-Id: <1619608082-4187-1-git-send-email-wanpengli@tencent.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Large pages not being created properly may result in increased memory
access time. The 'lpages' kvm stat used to keep track of the current
number of large pages in the system, but with TDP MMU enabled the stat
is not showing the correct number.
This patch extends the lpages counter to cover the TDP case.
Signed-off-by: Md Shahadat Hossain Shahin <shahinmd@amazon.de>
Cc: Bartosz Szczepanek <bsz@amazon.de>
Message-Id: <1619783551459.35424@amazon.de>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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In kvm_tdp_mmu_map(), while iterating TDP MMU page table entries, it is
possible SPTE has already been frozen by another thread but the frozen
is not done yet, for instance, when another thread is still in middle of
zapping large page. In this case, the !is_shadow_present_pte() check
for old SPTE in tdp_mmu_for_each_pte() may hit true, and in this case
allocating new page table is unnecessary since tdp_mmu_set_spte_atomic()
later will return false and page table will need to be freed. Add
is_removed_spte() check before allocating new page table to avoid this.
Signed-off-by: Kai Huang <kai.huang@intel.com>
Message-Id: <20210429041226.50279-1-kai.huang@intel.com>
Reviewed-by: Ben Gardon <bgardon@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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The generic/464 xfstest causes kAFS to emit occasional warnings of the
form:
kAFS: vnode modified {100055:8a} 30->31 YFS.StoreData64 (c=6015)
This indicates that the data version received back from the server did not
match the expected value (the DV should be incremented monotonically for
each individual modification op committed to a vnode).
What is happening is that a lookup call is doing a bulk status fetch
speculatively on a bunch of vnodes in a directory besides getting the
status of the vnode it's actually interested in. This is racing with a
StoreData operation (though it could also occur with, say, a MakeDir op).
On the client, a modification operation locks the vnode, but the bulk
status fetch only locks the parent directory, so no ordering is imposed
there (thereby avoiding an avenue to deadlock).
On the server, the StoreData op handler doesn't lock the vnode until it's
received all the request data, and downgrades the lock after committing the
data until it has finished sending change notifications to other clients -
which allows the status fetch to occur before it has finished.
This means that:
- a status fetch can access the target vnode either side of the exclusive
section of the modification
- the status fetch could start before the modification, yet finish after,
and vice-versa.
- the status fetch and the modification RPCs can complete in either order.
- the status fetch can return either the before or the after DV from the
modification.
- the status fetch might regress the locally cached DV.
Some of these are handled by the previous fix[1], but that's not sufficient
because it checks the DV it received against the DV it cached at the start
of the op, but the DV might've been updated in the meantime by a locally
generated modification op.
Fix this by the following means:
(1) Keep track of when we're performing a modification operation on a
vnode. This is done by marking vnode parameters with a 'modification'
note that causes the AFS_VNODE_MODIFYING flag to be set on the vnode
for the duration.
(2) Alter the speculation race detection to ignore speculative status
fetches if either the vnode is marked as being modified or the data
version number is not what we expected.
Note that whilst the "vnode modified" warning does get recovered from as it
causes the client to refetch the status at the next opportunity, it will
also invalidate the pagecache, so changes might get lost.
Fixes: a9e5c87ca744 ("afs: Fix speculative status fetch going out of order wrt to modifications")
Reported-by: Marc Dionne <marc.dionne@auristor.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Tested-and-reviewed-by: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
Link: https://lore.kernel.org/r/160605082531.252452.14708077925602709042.stgit@warthog.procyon.org.uk/ [1]
Link: https://lore.kernel.org/linux-fsdevel/161961335926.39335.2552653972195467566.stgit@warthog.procyon.org.uk/ # v1
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Commit 29efc390b946 ("md/md0: optimize raid0 discard handling") and
commit d30588b2731f ("md/raid10: improve raid10 discard request")
remove MD raid0's and raid10's inability to properly handle large
discards. So eliminate associated constraints from dm-raid's support.
Depends-on: 29efc390b946 ("md/md0: optimize raid0 discard handling")
Depends-on: d30588b2731f ("md/raid10: improve raid10 discard request")
Reported-by: Matthew Ruffell <matthew.ruffell@canonical.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
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It appears that unmap_mapping_range() actually takes a 'size' as its third
argument rather than a location, the current calling fashion causes
unnecessary amount of unmapping to occur.
Link: https://lkml.kernel.org/r/20210420002821.2749748-1-jane.chu@oracle.com
Fixes: 6100e34b2526e ("mm, memory_failure: Teach memory_failure() about dev_pagemap pages")
Signed-off-by: Jane Chu <jane.chu@oracle.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Reviewed-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: Dave Jiang <dave.jiang@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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There are a couple of kernel-doc comments in include/linux/mmzone.h but
they have minor formatting issues that would cause kernel-doc warnings.
Fix the formatting of those comments, add missing Return: descriptions and
link include/linux/mmzone.h to Documentation/core-api/mm-api.rst
Link: https://lkml.kernel.org/r/20210426141927.1314326-2-rppt@kernel.org
Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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On !ARCH_SUPPORTS_DEBUG_PAGEALLOC (like ia64) debug_pagealloc=1 implies
page_poison=on:
if (page_poisoning_enabled() ||
(!IS_ENABLED(CONFIG_ARCH_SUPPORTS_DEBUG_PAGEALLOC) &&
debug_pagealloc_enabled()))
static_branch_enable(&_page_poisoning_enabled);
page_poison=on needs to override init_on_free=1.
Before the change it did not work as expected for the following case:
- have PAGE_POISONING=y
- have page_poison unset
- have !ARCH_SUPPORTS_DEBUG_PAGEALLOC arch (like ia64)
- have init_on_free=1
- have debug_pagealloc=1
That way we get both keys enabled:
- static_branch_enable(&init_on_free);
- static_branch_enable(&_page_poisoning_enabled);
which leads to poisoned pages returned for __GFP_ZERO pages.
After the change we execute only:
- static_branch_enable(&_page_poisoning_enabled);
and ignore init_on_free=1.
Link: https://lkml.kernel.org/r/20210329222555.3077928-1-slyfox@gentoo.org
Link: https://lkml.org/lkml/2021/3/26/443
Fixes: 8db26a3d4735 ("mm, page_poison: use static key more efficiently")
Signed-off-by: Sergei Trofimovich <slyfox@gentoo.org>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: David Hildenbrand <david@redhat.com>
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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There are cases where the page_pool need to refill with pages from the
page allocator. Some workloads cause the page_pool to release pages
instead of recycling these pages.
For these workload it can improve performance to bulk alloc pages from the
page-allocator to refill the alloc cache.
For XDP-redirect workload with 100G mlx5 driver (that use page_pool)
redirecting xdp_frame packets into a veth, that does XDP_PASS to create an
SKB from the xdp_frame, which then cannot return the page to the
page_pool.
Performance results under GitHub xdp-project[1]:
[1] https://github.com/xdp-project/xdp-project/blob/master/areas/mem/page_pool06_alloc_pages_bulk.org
Mel: The patch "net: page_pool: convert to use alloc_pages_bulk_array
variant" was squashed with this patch. From the test page, the array
variant was superior with one of the test results as follows.
Kernel XDP stats CPU pps Delta
Baseline XDP-RX CPU total 3,771,046 n/a
List XDP-RX CPU total 3,940,242 +4.49%
Array XDP-RX CPU total 4,249,224 +12.68%
Link: https://lkml.kernel.org/r/20210325114228.27719-10-mgorman@techsingularity.net
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Reviewed-by: Alexander Lobakin <alobakin@pm.me>
Cc: Alexander Duyck <alexander.duyck@gmail.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Chuck Lever <chuck.lever@oracle.com>
Cc: David Miller <davem@davemloft.net>
Cc: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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In preparation for next patch, move the dma mapping into its own function,
as this will make it easier to follow the changes.
[ilias.apalodimas: make page_pool_dma_map return boolean]
Link: https://lkml.kernel.org/r/20210325114228.27719-9-mgorman@techsingularity.net
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Reviewed-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Reviewed-by: Alexander Lobakin <alobakin@pm.me>
Cc: Alexander Duyck <alexander.duyck@gmail.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Chuck Lever <chuck.lever@oracle.com>
Cc: David Miller <davem@davemloft.net>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Reduce the rate at which nfsd threads hammer on the page allocator. This
improves throughput scalability by enabling the threads to run more
independently of each other.
[mgorman: Update interpretation of alloc_pages_bulk return value]
Link: https://lkml.kernel.org/r/20210325114228.27719-8-mgorman@techsingularity.net
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Reviewed-by: Alexander Lobakin <alobakin@pm.me>
Cc: Alexander Duyck <alexander.duyck@gmail.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: David Miller <davem@davemloft.net>
Cc: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Cc: Jesper Dangaard Brouer <brouer@redhat.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Patch series "SUNRPC consumer for the bulk page allocator"
This patch set and the measurements below are based on yesterday's
bulk allocator series:
git://git.kernel.org/pub/scm/linux/kernel/git/mel/linux.git mm-bulk-rebase-v5r9
The patches change SUNRPC to invoke the array-based bulk allocator
instead of alloc_page().
The micro-benchmark results are promising. I ran a mixture of 256KB
reads and writes over NFSv3. The server's kernel is built with KASAN
enabled, so the comparison is exaggerated but I believe it is still
valid.
I instrumented svc_recv() to measure the latency of each call to
svc_alloc_arg() and report it via a trace point. The following results
are averages across the trace events.
Single page: 25.007 us per call over 532,571 calls
Bulk list: 6.258 us per call over 517,034 calls
Bulk array: 4.590 us per call over 517,442 calls
This patch (of 2)
Refactor:
I'm about to use the loop variable @i for something else.
As far as the "i++" is concerned, that is a post-increment. The
value of @i is not used subsequently, so the increment operator
is unnecessary and can be removed.
Also note that nfsd_read_actor() was renamed nfsd_splice_actor()
by commit cf8208d0eabd ("sendfile: convert nfsd to
splice_direct_to_actor()").
Link: https://lkml.kernel.org/r/20210325114228.27719-7-mgorman@techsingularity.net
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Reviewed-by: Alexander Lobakin <alobakin@pm.me>
Cc: Alexander Duyck <alexander.duyck@gmail.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: David Miller <davem@davemloft.net>
Cc: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Cc: Jesper Dangaard Brouer <brouer@redhat.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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When __alloc_pages_bulk() got introduced two callers of __rmqueue_pcplist
exist and the compiler chooses to not inline this function.
./scripts/bloat-o-meter vmlinux-before vmlinux-inline__rmqueue_pcplist
add/remove: 0/1 grow/shrink: 2/0 up/down: 164/-125 (39)
Function old new delta
rmqueue 2197 2296 +99
__alloc_pages_bulk 1921 1986 +65
__rmqueue_pcplist 125 - -125
Total: Before=19374127, After=19374166, chg +0.00%
modprobe page_bench04_bulk loops=$((10**7))
Type:time_bulk_page_alloc_free_array
- Per elem: 106 cycles(tsc) 29.595 ns (step:64)
- (measurement period time:0.295955434 sec time_interval:295955434)
- (invoke count:10000000 tsc_interval:1065447105)
Before:
- Per elem: 110 cycles(tsc) 30.633 ns (step:64)
Link: https://lkml.kernel.org/r/20210325114228.27719-6-mgorman@techsingularity.net
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Reviewed-by: Alexander Lobakin <alobakin@pm.me>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Alexander Duyck <alexander.duyck@gmail.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Chuck Lever <chuck.lever@oracle.com>
Cc: David Miller <davem@davemloft.net>
Cc: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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