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Don't snapshot pending INIT/SIPI events prior to checking nested events,
architecturally there's nothing wrong with KVM processing (dropping) a
SIPI that is received immediately after synthesizing a VM-Exit. Taking
and consuming the snapshot makes the flow way more subtle than it needs
to be, e.g. nVMX consumes/clears events that trigger VM-Exit (INIT/SIPI),
and so at first glance it appears that KVM is double-dipping on pending
INITs and SIPIs. But that's not the case because INIT is blocked
unconditionally in VMX root mode the CPU cannot be in wait-for_SIPI after
VM-Exit, i.e. the paths that truly consume the snapshot are unreachable
if apic->pending_events is modified by kvm_check_nested_events().
nSVM is a similar story as GIF is cleared by the CPU on VM-Exit; INIT is
blocked regardless of whether or not it was pending prior to VM-Exit.
Drop the snapshot logic so that a future fix doesn't create weirdness
when kvm_vcpu_running()'s call to kvm_check_nested_events() is moved to
vcpu_block(). In that case, kvm_check_nested_events() will be called
immediately before kvm_apic_accept_events(), which raises the obvious
question of why that change doesn't break the snapshot logic.
Note, there is a subtle functional change. Previously, KVM would clear
pending SIPIs if and only SIPI was pending prior to VM-Exit, whereas now
KVM clears pending SIPI unconditionally if INIT+SIPI are blocked. The
latter is architecturally allowed, as SIPI is ignored if the CPU is not
in wait-for-SIPI mode (arguably, KVM should be even more aggressive in
dropping SIPIs). It is software's responsibility to ensure the SIPI is
delivered, i.e. software shouldn't be firing INIT-SIPI at a CPU until
it knows with 100% certaining that the target CPU isn't in VMX root mode.
Furthermore, the existing code is extra weird as SIPIs that arrive after
VM-Exit _are_ dropped if there also happened to be a pending SIPI before
VM-Exit.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220921003201.1441511-10-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Rename and invert kvm_vcpu_latch_init() to kvm_apic_init_sipi_allowed()
so as to match the behavior of {interrupt,nmi,smi}_allowed(), and expose
the helper so that it can be used by kvm_vcpu_has_events() to determine
whether or not an INIT or SIPI is pending _and_ can be taken immediately.
Opportunistically replaced usage of the "latch" terminology with "blocked"
and/or "allowed", again to align with KVM's terminology used for all other
event types.
No functional change intended.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220921003201.1441511-4-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Bug the VM if retrieving the x2APIC MSR/register while processing an
accelerated vAPIC trap VM-Exit fails. In theory it's impossible for the
lookup to fail as hardware has already validated the register, but bugs
happen, and not checking the result of kvm_lapic_msr_read() would result
in consuming the uninitialized "val" if a KVM or hardware bug occurs.
Fixes: 1bd9dfec9fd4 ("KVM: x86: Do not block APIC write for non ICR registers")
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220804235028.1766253-1-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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The commit 5413bcba7ed5 ("KVM: x86: Add support for vICR APIC-write
VM-Exits in x2APIC mode") introduces logic to prevent APIC write
for offset other than ICR in kvm_apic_write_nodecode() function.
This breaks x2AVIC support, which requires KVM to trap and emulate
x2APIC MSR writes.
Therefore, removes the warning and modify to logic to allow MSR write.
Fixes: 5413bcba7ed5 ("KVM: x86: Add support for vICR APIC-write VM-Exits in x2APIC mode")
Cc: Zeng Guang <guang.zeng@intel.com>
Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
Message-Id: <20220725053356.4275-1-suravee.suthikulpanit@amd.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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When applying the hotplug hack to match x2APIC IDs for vCPUs in xAPIC
mode, check the target APID ID for being unaddressable in xAPIC mode
instead of checking the vCPU's x2APIC ID, and in that case proceed as
if apic_x2apic_mode(vcpu) were true.
Functionally, it does not matter whether you compare kvm_x2apic_id(apic)
or mda with 0xff, since the two values are then checked for equality.
But in isolation, checking the x2APIC ID takes an unnecessary dependency
on the x2APIC ID being read-only (which isn't strictly true on AMD CPUs,
and is difficult to document as well); it also requires KVM to fallthrough
and check the xAPIC ID as well to deal with a writable xAPIC ID, whereas
the xAPIC ID _can't_ match a target ID greater than 0xff.
Opportunistically reword the comment to call out the various subtleties,
and to fix a typo reported by Zhang Jiaming.
No functional change intended.
Cc: Zhang Jiaming <jiaming@nfschina.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Add a helper to update KVM's in-kernel local APIC in response to MCG_CAP
being changed by userspace to fix multiple bugs. First and foremost,
KVM needs to check that there's an in-kernel APIC prior to dereferencing
vcpu->arch.apic. Beyond that, any "new" LVT entries need to be masked,
and the APIC version register needs to be updated as it reports out the
number of LVT entries.
Fixes: 4b903561ec49 ("KVM: x86: Add Corrected Machine Check Interrupt (CMCI) emulation to lapic.")
Reported-by: syzbot+8cdad6430c24f396f158@syzkaller.appspotmail.com
Cc: Siddh Raman Pant <code@siddh.me>
Cc: Jue Wang <juew@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
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Initialize the number of LVT entries during APIC creation, else the field
will be incorrectly left '0' if userspace never invokes KVM_X86_SETUP_MCE.
Add and use a helper to calculate the number of entries even though
MCG_CMCI_P is not set by default in vcpu->arch.mcg_cap. Relying on that
to always be true is unnecessarily risky, and subtle/confusing as well.
Fixes: 4b903561ec49 ("KVM: x86: Add Corrected Machine Check Interrupt (CMCI) emulation to lapic.")
Reported-by: Xiaoyao Li <xiaoyao.li@intel.com>
Cc: Jue Wang <juew@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
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APICv should be deactivated on vCPU that has APIC disabled.
Therefore, call kvm_vcpu_update_apicv() when changing
APIC mode, and add additional check for APIC disable mode
when determine APICV activation,
Suggested-by: Maxim Levitsky <mlevitsk@redhat.com>
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
Message-Id: <20220519102709.24125-9-suravee.suthikulpanit@amd.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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To signify that the macros only support 8-bit xAPIC destination ID.
Suggested-by: Maxim Levitsky <mlevitsk@redhat.com>
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Reviewed-by: Pankaj Gupta <pankaj.gupta@amd.com>
Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20220519102709.24125-3-suravee.suthikulpanit@amd.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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This patch calculates the number of lvt entries as part of
KVM_X86_MCE_SETUP conditioned on the presence of MCG_CMCI_P bit in
MCG_CAP and stores result in kvm_lapic. It translats from APIC_LVTx
register to index in lapic_lvt_entry enum. It extends the APIC_LVTx
macro as well as other lapic write/reset handling etc to support
Corrected Machine Check Interrupt.
Signed-off-by: Jue Wang <juew@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20220610171134.772566-5-juew@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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An APIC_LVTx macro is introduced to calcualte the APIC_LVTx register
offset based on the index in the lapic_lvt_entry enum. Later patches
will extend the APIC_LVTx macro to support the APIC_LVTCMCI register
in order to implement Corrected Machine Check Interrupt signaling.
Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Jue Wang <juew@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20220610171134.772566-4-juew@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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This patch defines a lapic_lvt_entry enum used as explicit indices to
the apic_lvt_mask array. In later patches a LVT_CMCI will be added to
implement the Corrected Machine Check Interrupt signaling.
Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Jue Wang <juew@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20220610171134.772566-3-juew@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Refactor APIC_VERSION so that the maximum number of LVT entries is
inserted at runtime rather than compile time. This will be used in a
subsequent commit to expose the LVT CMCI Register to VMs that support
Corrected Machine Check error counting/signaling
(IA32_MCG_CAP.MCG_CMCI_P=1).
Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Jue Wang <juew@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20220610171134.772566-2-juew@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Move the per-vCPU apicv_active flag into KVM's local APIC instance.
APICv is fully dependent on an in-kernel local APIC, but that's not at
all clear when reading the current code due to the flag being stored in
the generic kvm_vcpu_arch struct.
No functional change intended.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220614230548.3852141-5-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Drop the unused @vcpu parameter from hwapic_isr_update(). AMD/AVIC is
unlikely to implement the helper, and VMX/APICv doesn't need the vCPU as
it operates on the current VMCS. The result is somewhat odd, but allows
for a decent amount of (future) cleanup in the APIC code.
No functional change intended.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220614230548.3852141-3-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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s390:
* add an interface to provide a hypervisor dump for secure guests
* improve selftests to show tests
x86:
* Intel IPI virtualization
* Allow getting/setting pending triple fault with KVM_GET/SET_VCPU_EVENTS
* PEBS virtualization
* Simplify PMU emulation by just using PERF_TYPE_RAW events
* More accurate event reinjection on SVM (avoid retrying instructions)
* Allow getting/setting the state of the speaker port data bit
* Rewrite gfn-pfn cache refresh
* Refuse starting the module if VM-Entry/VM-Exit controls are inconsistent
* "Notify" VM exit
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Neither of these settings should be changed by the guest and it is
a burden to support it in the acceleration code, so just inhibit
this code instead.
Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Message-Id: <20220606180829.102503-3-mlevitsk@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Add kvm_caps to hold a variety of capabilites and defaults that aren't
handled by kvm_cpu_caps because they aren't CPUID bits in order to reduce
the amount of boilerplate code required to add a new feature. The vast
majority (all?) of the caps interact with vendor code and are written
only during initialization, i.e. should be tagged __read_mostly, declared
extern in x86.h, and exported.
No functional change intended.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220524135624.22988-4-chenyi.qiang@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Upcoming Intel CPUs will support virtual x2APIC MSR writes to the vICR,
i.e. will trap and generate an APIC-write VM-Exit instead of intercepting
the WRMSR. Add support for handling "nodecode" x2APIC writes, which
were previously impossible.
Note, x2APIC MSR writes are 64 bits wide.
Signed-off-by: Zeng Guang <guang.zeng@intel.com>
Message-Id: <20220419153516.11739-1-guang.zeng@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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The timer is disarmed when switching between TSC deadline and other modes;
however, the pending timer is still in-flight, so let's accurately remove
any traces of the previous mode.
Fixes: 4427593258 ("KVM: x86: thoroughly disarm LAPIC timer around TSC deadline switch")
Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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In commit ec0671d5684a ("KVM: LAPIC: Delay trace_kvm_wait_lapic_expire
tracepoint to after vmexit", 2019-06-04), trace_kvm_wait_lapic_expire
was moved after guest_exit_irqoff() because invoking tracepoints within
kvm_guest_enter/kvm_guest_exit caused a lockdep splat.
These days this is not necessary, because commit 87fa7f3e98a1 ("x86/kvm:
Move context tracking where it belongs", 2020-07-09) restricted
the RCU extended quiescent state to be closer to vmentry/vmexit.
Moving the tracepoint back to __kvm_wait_lapic_expire is more accurate,
because it will be reported even if vcpu_enter_guest causes multiple
vmentries via the IPI/Timer fast paths, and it allows the removal of
advance_expire_delta.
Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
Message-Id: <1650961551-38390-1-git-send-email-wanpengli@tencent.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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When kvm_irq_delivery_to_apic_fast() is called with APIC_DEST_SELF
shorthand, 'src' must not be NULL. Crash the VM with KVM_BUG_ON()
instead of crashing the host.
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20220325132140.25650-3-vkuznets@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Hide the lapic's "raw" write helper inside lapic.c to force non-APIC code
to go through proper helpers when modification the vAPIC state. Keep the
read helper visible to outsiders for now, refactoring KVM to hide it too
is possible, it will just take more work to do so.
No functional change intended.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220204214205.3306634-11-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Emulate the x2APIC ICR as a single 64-bit register, as opposed to forking
it across ICR and ICR2 as two 32-bit registers. This mirrors hardware
behavior for Intel's upcoming IPI virtualization support, which does not
split the access.
Previous versions of Intel's SDM and AMD's APM don't explicitly state
exactly how ICR is reflected in the vAPIC page for x2APIC, KVM just
happened to speculate incorrectly.
Handling the upcoming behavior is necessary in order to maintain
backwards compatibility with KVM_{G,S}ET_LAPIC, e.g. failure to shuffle
the 64-bit ICR to ICR+ICR2 and vice versa would break live migration if
IPI virtualization support isn't symmetrical across the source and dest.
Cc: Zeng Guang <guang.zeng@intel.com>
Cc: Chao Gao <chao.gao@intel.com>
Cc: Maxim Levitsky <mlevitsk@redhat.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220204214205.3306634-10-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Add helpers to handle 64-bit APIC read/writes via MSRs to deduplicate the
x2APIC and Hyper-V code needed to service reads/writes to ICR. Future
support for IPI virtualization will add yet another path where KVM must
handle 64-bit APIC MSR reads/write (to ICR).
Opportunistically fix the comment in the write path; ICR2 holds the
destination (if there's no shorthand), not the vector.
No functional change intended.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220204214205.3306634-9-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Make the low level read/write lapic helpers static, any accesses to the
local APIC from vendor code or non-APIC code should be routed through
proper helpers.
No functional change intended.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220204214205.3306634-8-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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WARN if KVM emulates an IPI without clearing the BUSY flag, failure to do
so could hang the guest if it waits for the IPI be sent.
Opportunistically use APIC_ICR_BUSY macro instead of open coding the
magic number, and add a comment to clarify why kvm_recalculate_apic_map()
is unconditionally invoked (it's really, really confusing for IPIs due to
the existence of fast paths that don't trigger a potential recalc).
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220204214205.3306634-7-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Don't bother rewriting the ICR value into the vAPIC page on an AVIC IPI
virtualization failure, the access is a trap, i.e. the value has already
been written to the vAPIC page. The one caveat is if hardware left the
BUSY flag set (which appears to happen somewhat arbitrarily), in which
case go through the "nodecode" APIC-write path in order to clear the BUSY
flag.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220204214205.3306634-6-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Use the "raw" helper to read the vAPIC register after an APIC-write trap
VM-Exit. Hardware is responsible for vetting the write, and the caller
is responsible for sanitizing the offset. This is a functional change,
as it means KVM will consume whatever happens to be in the vAPIC page if
the write was dropped by hardware. But, unless userspace deliberately
wrote garbage into the vAPIC page via KVM_SET_LAPIC, the value should be
zero since it's not writable by the guest.
This aligns common x86 with SVM's AVIC logic, i.e. paves the way for
using the nodecode path to handle APIC-write traps when AVIC is enabled.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220204214205.3306634-4-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Move the vAPIC offset adjustments done in the APIC-write trap path from
common x86 to VMX in anticipation of using the nodecode path for SVM's
AVIC. The adjustment reflects hardware behavior, i.e. it's technically a
property of VMX, no common x86. SVM's AVIC behavior is identical, so
it's a bit of a moot point, the goal is purely to make it easier to
understand why the adjustment is ok.
No functional change intended.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220204214205.3306634-3-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Emulating writes to SELF_IPI with a write to ICR has an unwanted side effect:
the value of ICR in vAPIC page gets changed. The lists SELF_IPI as write-only,
with no associated MMIO offset, so any write should have no visible side
effect in the vAPIC page.
Reported-by: Chao Gao <chao.gao@intel.com>
Reviewed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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In emulation of writing to cr8, one of the lowest four bits in TPR[3:0]
is kept.
According to Intel SDM 10.8.6.1(baremetal scenario):
"APIC.TPR[bits 7:4] = CR8[bits 3:0], APIC.TPR[bits 3:0] = 0";
and SDM 28.3(use TPR shadow):
"MOV to CR8. The instruction stores bits 3:0 of its source operand into
bits 7:4 of VTPR; the remainder of VTPR (bits 3:0 and bits 31:8) are
cleared.";
and AMD's APM 16.6.4:
"Task Priority Sub-class (TPS)-Bits 3 : 0. The TPS field indicates the
current sub-priority to be used when arbitrating lowest-priority messages.
This field is written with zero when TPR is written using the architectural
CR8 register.";
so in KVM emulated scenario, clear TPR[3:0] to make a consistent behavior
as in other scenarios.
This doesn't impact evaluation and delivery of pending virtual interrupts
because processor does not use the processor-priority sub-class to
determine which interrupts to delivery and which to inhibit.
Sub-class is used by hardware to arbitrate lowest priority interrupts,
but KVM just does a round-robin style delivery.
Fixes: b93463aa59d6 ("KVM: Accelerated apic support")
Signed-off-by: Zhenzhong Duan <zhenzhong.duan@intel.com>
Reviewed-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220210094506.20181-1-zhenzhong.duan@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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All their invocations are conditional on vcpu->arch.apicv_active,
meaning that they need not be implemented by vendor code: even
though at the moment both vendors implement APIC virtualization,
all of them can be optional. In fact SVM does not need many of
them, and their implementation can be deleted now.
Reviewed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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As commit 0c5f81dad46 ("KVM: LAPIC: Inject timer interrupt via posted
interrupt") mentioned that the host admin should well tune the guest
setup, so that vCPUs are placed on isolated pCPUs, and with several pCPUs
surplus for *busy* housekeeping. In this setup, it is preferrable to
disable mwait/hlt/pause vmexits to keep the vCPUs in non-root mode.
However, if only some guests isolated and others not, they would not
have any benefit from posted timer interrupts, and at the same time lose
VMX preemption timer fast paths because kvm_can_post_timer_interrupt()
returns true and therefore forces kvm_can_use_hv_timer() to false.
By guaranteeing that posted-interrupt timer is only used if MWAIT or
HLT are done without vmexit, KVM can make a better choice and use the
VMX preemption timer and the corresponding fast paths.
Reported-by: Aili Yao <yaoaili@kingsoft.com>
Reviewed-by: Sean Christopherson <seanjc@google.com>
Cc: Aili Yao <yaoaili@kingsoft.com>
Cc: Sean Christopherson <seanjc@google.com>
Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
Message-Id: <1643112538-36743-1-git-send-email-wanpengli@tencent.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Define and use a static_call() for kvm_x86_ops.vcpu_deliver_sipi_vector(),
mostly so that the op is defined in kvm-x86-ops.h. This will allow using
KVM_X86_OP in vendor code to wire up the implementation. Any performance
gains eeked out by using static_call() is a happy bonus and not the
primary motiviation.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220128005208.4008533-6-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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kvm_apic_update_apicv is called when AVIC is still active, thus IRR bits
can be set by the CPU after it is called, and don't cause the irr_pending
to be set to true.
Also logic in avic_kick_target_vcpu doesn't expect a race with this
function so to make it simple, just keep irr_pending set to true and
let the next interrupt injection to the guest clear it.
Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Message-Id: <20220207155447.840194-9-mlevitsk@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Handle non-APICv interrupt delivery in vendor code, even though it means
VMX and SVM will temporarily have duplicate code. SVM's AVIC has a race
condition that requires KVM to fall back to legacy interrupt injection
_after_ the interrupt has been logged in the vIRR, i.e. to fix the race,
SVM will need to open code the full flow anyways[*]. Refactor the code
so that the SVM bug without introducing other issues, e.g. SVM would
return "success" and thus invoke trace_kvm_apicv_accept_irq() even when
delivery through the AVIC failed, and to opportunistically prepare for
using KVM_X86_OP to fill each vendor's kvm_x86_ops struct, which will
rely on the vendor function matching the kvm_x86_op pointer name.
No functional change intended.
[*] https://lore.kernel.org/all/20211213104634.199141-4-mlevitsk@redhat.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220128005208.4008533-3-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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The below warning is splatting during guest reboot.
------------[ cut here ]------------
WARNING: CPU: 0 PID: 1931 at arch/x86/kvm/x86.c:10322 kvm_arch_vcpu_ioctl_run+0x874/0x880 [kvm]
CPU: 0 PID: 1931 Comm: qemu-system-x86 Tainted: G I 5.17.0-rc1+ #5
RIP: 0010:kvm_arch_vcpu_ioctl_run+0x874/0x880 [kvm]
Call Trace:
<TASK>
kvm_vcpu_ioctl+0x279/0x710 [kvm]
__x64_sys_ioctl+0x83/0xb0
do_syscall_64+0x3b/0xc0
entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x7fd39797350b
This can be triggered by not exposing tsc-deadline mode and doing a reboot in
the guest. The lapic_shutdown() function which is called in sys_reboot path
will not disarm the flying timer, it just masks LVTT. lapic_shutdown() clears
APIC state w/ LVT_MASKED and timer-mode bit is 0, this can trigger timer-mode
switch between tsc-deadline and oneshot/periodic, which can result in preemption
timer be cancelled in apic_update_lvtt(). However, We can't depend on this when
not exposing tsc-deadline mode and oneshot/periodic modes emulated by preemption
timer. Qemu will synchronise states around reset, let's cancel preemption timer
under KVM_SET_LAPIC.
Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
Message-Id: <1643102220-35667-1-git-send-email-wanpengli@tencent.com>
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Unexport switch_to_{hv,sw}_timer() now that common x86 handles the
transitions.
No functional change intended.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Message-Id: <20211208015236.1616697-9-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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This allows to see how many interrupts were delivered via the
APICv/AVIC from the host.
Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Message-Id: <20211209115440.394441-3-mlevitsk@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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merge pv_eoi_get_pending and pv_eoi_clr_pending into a single
function pv_eoi_test_and_clear_pending, which returns and clear
the value of the pending bit.
This makes it possible to clear the pending bit only if the guest
had set it, and otherwise skip the call to pv_eoi_put_user().
This can save up to 300 nsec on AMD EPYC processors.
Suggested-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Li RongQing <lirongqing@baidu.com>
Message-Id: <1636026974-50555-2-git-send-email-lirongqing@baidu.com>
Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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If guest gives MSR_KVM_PV_EOI_EN a wrong value, this printk() will
be trigged, and kernel log is spammed with the useless message
Fixes: 0d88800d5472 ("kvm: x86: ioapic and apic debug macros cleanup")
Reported-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Li RongQing <lirongqing@baidu.com>
Cc: stable@kernel.org
Message-Id: <1636026974-50555-1-git-send-email-lirongqing@baidu.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Add helpers to wake and query a blocking vCPU. In addition to providing
nice names, the helpers reduce the probability of KVM neglecting to use
kvm_arch_vcpu_get_wait().
No functional change intended.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20211009021236.4122790-20-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Everywhere we use kvm_for_each_vpcu(), we use an int as the vcpu
index. Unfortunately, we're about to move rework the iterator,
which requires this to be upgrade to an unsigned long.
Let's bite the bullet and repaint all of it in one go.
Signed-off-by: Marc Zyngier <maz@kernel.org>
Message-Id: <20211116160403.4074052-7-maz@kernel.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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The IRTE for an assigned device can trigger a POSTED_INTR_VECTOR even
if APICv is disabled on the vCPU that receives it. In that case, the
interrupt will just cause a vmexit and leave the ON bit set together
with the PIR bit corresponding to the interrupt.
Right now, the interrupt would not be delivered until APICv is re-enabled.
However, fixing this is just a matter of always doing the PIR->IRR
synchronization, even if the vCPU has temporarily disabled APICv.
This is not a problem for performance, or if anything it is an
improvement. First, in the common case where vcpu->arch.apicv_active is
true, one fewer check has to be performed. Second, static_call_cond will
elide the function call if APICv is not present or disabled. Finally,
in the case for AMD hardware we can remove the sync_pir_to_irr callback:
it is only needed for apic_has_interrupt_for_ppr, and that function
already has a fallback for !APICv.
Cc: stable@vger.kernel.org
Co-developed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Reviewed-by: David Matlack <dmatlack@google.com>
Message-Id: <20211123004311.2954158-4-pbonzini@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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* Fix misuse of gfn-to-pfn cache when recording guest steal time / preempted status
* Fix selftests on APICv machines
* Fix sparse warnings
* Fix detection of KVM features in CPUID
* Cleanups for bogus writes to MSR_KVM_PV_EOI_EN
* Fixes and cleanups for MSR bitmap handling
* Cleanups for INVPCID
* Make x86 KVM_SOFT_MAX_VCPUS consistent with other architectures
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When kvm_gfn_to_hva_cache_init() call from kvm_lapic_set_pv_eoi() fails,
MSR write to MSR_KVM_PV_EOI_EN results in #GP so it is reasonable to
expect that the value we keep internally in KVM wasn't updated.
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20211108152819.12485-3-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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kvm_lapic_enable_pv_eoi() is a misnomer as the function is also
used to disable PV EOI. Rename it to kvm_lapic_set_pv_eoi().
No functional change intended.
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20211108152819.12485-2-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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WARN if the static keys used to track if any vCPU has disabled its APIC
are left elevated at module exit. Unlike the underflow case, nothing in
the static key infrastructure will complain if a key is left elevated,
and because an elevated key only affects performance, nothing in KVM will
fail if either key is improperly incremented.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20211013003554.47705-3-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Revert a change to open code bits of kvm_lapic_set_base() when emulating
APIC RESET to fix an apic_hw_disabled underflow bug due to arch.apic_base
and apic_hw_disabled being unsyncrhonized when the APIC is created. If
kvm_arch_vcpu_create() fails after creating the APIC, kvm_free_lapic()
will see the initialized-to-zero vcpu->arch.apic_base and decrement
apic_hw_disabled without KVM ever having incremented apic_hw_disabled.
Using kvm_lapic_set_base() in kvm_lapic_reset() is also desirable for a
potential future where KVM supports RESET outside of vCPU creation, in
which case all the side effects of kvm_lapic_set_base() are needed, e.g.
to handle the transition from x2APIC => xAPIC.
Alternatively, KVM could temporarily increment apic_hw_disabled (and call
kvm_lapic_set_base() at RESET), but that's a waste of cycles and would
impact the performance of other vCPUs and VMs. The other subtle side
effect is that updating the xAPIC ID needs to be done at RESET regardless
of whether the APIC was previously enabled, i.e. kvm_lapic_reset() needs
an explicit call to kvm_apic_set_xapic_id() regardless of whether or not
kvm_lapic_set_base() also performs the update. That makes stuffing the
enable bit at vCPU creation slightly more palatable, as doing so affects
only the apic_hw_disabled key.
Opportunistically tweak the comment to explicitly call out the connection
between vcpu->arch.apic_base and apic_hw_disabled, and add a comment to
call out the need to always do kvm_apic_set_xapic_id() at RESET.
Underflow scenario:
kvm_vm_ioctl() {
kvm_vm_ioctl_create_vcpu() {
kvm_arch_vcpu_create() {
if (something_went_wrong)
goto fail_free_lapic;
/* vcpu->arch.apic_base is initialized when something_went_wrong is false. */
kvm_vcpu_reset() {
kvm_lapic_reset(struct kvm_vcpu *vcpu, bool init_event) {
vcpu->arch.apic_base = APIC_DEFAULT_PHYS_BASE | MSR_IA32_APICBASE_ENABLE;
}
}
return 0;
fail_free_lapic:
kvm_free_lapic() {
/* vcpu->arch.apic_base is not yet initialized when something_went_wrong is true. */
if (!(vcpu->arch.apic_base & MSR_IA32_APICBASE_ENABLE))
static_branch_slow_dec_deferred(&apic_hw_disabled); // <= underflow bug.
}
return r;
}
}
}
This (mostly) reverts commit 421221234ada41b4a9f0beeb08e30b07388bd4bd.
Fixes: 421221234ada ("KVM: x86: Open code necessary bits of kvm_lapic_set_base() at vCPU RESET")
Reported-by: syzbot+9fc046ab2b0cf295a063@syzkaller.appspotmail.com
Debugged-by: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20211013003554.47705-2-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Sean Christopherson
Suravee Suthikulpanit
Jue Wang
Paolo Bonzini
Maxim Levitsky
Zeng Guang
Wanpeng Li
Vitaly Kuznetsov
Zhenzhong Duan
Li RongQing
Marc Zyngier