- Add support for chained PMU counters in guests
- Improve SError handling
- Handle Neoverse N1 erratum #1349291
- Allow side-channel mitigation status to be migrated
- Standardise most AArch64 system register accesses to msr_s/mrs_s
- Fix host MPIDR corruption on 32bit
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Merge tag 'kvm-arm-for-5.3' of git://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm into HEAD
KVM/arm updates for 5.3
- Add support for chained PMU counters in guests
- Improve SError handling
- Handle Neoverse N1 erratum #1349291
- Allow side-channel mitigation status to be migrated
- Standardise most AArch64 system register accesses to msr_s/mrs_s
- Fix host MPIDR corruption on 32bit
Added toctree hooks for indexing. Hooks added only for newly added
files.
The hook for the top of the tree will be added in a later patch series
when a few more substantial changes have been added.
Signed-off-by: Luke Nowakowski-Krijger <lnowakow@eng.ucsd.edu>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Convert cpuid.txt to .rst format to be parsable by sphinx.
Change format and spacing to make function definitions and return values
much more clear. Also added a table that is parsable by sphinx and makes
the information much more clean. Updated Author email to their new
active email address. Added license identifier with the consent of the
author.
Signed-off-by: Luke Nowakowski-Krijger <lnowakow@eng.ucsd.edu>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Convert paravirt_opts.txt to .rst format to be able to be parsed by
sphinx.
Made some minor spacing and formatting corrections to make defintions
much more clear and easy to read. Added default kernel license to the
document.
Signed-off-by: Luke Nowakowski-Krijger <lnowakow@eng.ucsd.edu>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
On VMX, KVM currently does not re-enable irqs until after it has exited
the guest context. As a result, a tick that fires in the window between
VM-Exit and guest_exit_irqoff() will be accounted as system time. While
said window is relatively small, it's large enough to be problematic in
some configurations, e.g. if VM-Exits are consistently occurring a hair
earlier than the tick irq.
Intentionally toggle irqs back off so that guest_exit_irqoff() can be
used in lieu of guest_exit() in order to avoid the save/restore of flags
in guest_exit(). On my Haswell system, "nop; cli; sti" is ~6 cycles,
versus ~28 cycles for "pushf; pop <reg>; cli; push <reg>; popf".
Fixes: f2485b3e0c ("KVM: x86: use guest_exit_irqoff")
Reported-by: Wei Yang <w90p710@gmail.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Some events can provide a guest with information about other guests or the
host (e.g. L3 cache stats); providing the capability to restrict access
to a "safe" set of events would limit the potential for the PMU to be used
in any side channel attacks. This change introduces a new VM ioctl that
sets an event filter. If the guest attempts to program a counter for
any blacklisted or non-whitelisted event, the kernel counter won't be
created, so any RDPMC/RDMSR will show 0 instances of that event.
Signed-off-by: Eric Hankland <ehankland@google.com>
[Lots of changes. All remaining bugs are probably mine. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
We get a warning when build kernel W=1:
arch/x86/kvm/../../../virt/kvm/eventfd.c:48:1: warning: no previous prototype for ‘kvm_arch_irqfd_allowed’ [-Wmissing-prototypes]
kvm_arch_irqfd_allowed(struct kvm *kvm, struct kvm_irqfd *args)
^
The reason is kvm_arch_irqfd_allowed() is declared in arch/x86/kvm/irq.h,
which is not included by eventfd.c. Considering kvm_arch_irqfd_allowed()
is a weakly defined function in eventfd.c, remove the declaration to
kvm_host.h can fix this.
Signed-off-by: Yi Wang <wang.yi59@zte.com.cn>
Reviewed-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
The field "page" is initialized to KVM_UNMAPPED_PAGE when it is not used
(i.e. when the memory lives outside kernel control). So this check will
always end up using kunmap even for memremap regions.
Fixes: e45adf665a ("KVM: Introduce a new guest mapping API")
Cc: stable@vger.kernel.org
Signed-off-by: KarimAllah Ahmed <karahmed@amazon.de>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
As part of setting up the host context, we populate its
MPIDR by using cpu_logical_map(). It turns out that contrary
to arm64, cpu_logical_map() on 32bit ARM doesn't return the
*full* MPIDR, but a truncated version.
This leaves the host MPIDR slightly corrupted after the first
run of a VM, since we won't correctly restore the MPIDR on
exit. Oops.
Since we cannot trust cpu_logical_map(), let's adopt a different
strategy. We move the initialization of the host CPU context as
part of the per-CPU initialization (which, in retrospect, makes
a lot of sense), and directly read the MPIDR from the HW. This
is guaranteed to work on both arm and arm64.
Reported-by: Andre Przywara <Andre.Przywara@arm.com>
Tested-by: Andre Przywara <Andre.Przywara@arm.com>
Fixes: 32f1395519 ("arm/arm64: KVM: Statically configure the host's view of MPIDR")
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Retry tune per-vCPU timer_advance_ns if adaptive tuning goes insane which
can happen sporadically in product environment.
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Replace a magic 64-bit mask with a list of valid registers, computing
the same mask in the end.
Suggested-by: Liran Alon <liran.alon@oracle.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Currently, the {read,write}_sysreg_el*() accessors for accessing
particular ELs' sysregs in the presence of VHE rely on some local
hacks and define their system register encodings in a way that is
inconsistent with the core definitions in <asm/sysreg.h>.
As a result, it is necessary to add duplicate definitions for any
system register that already needs a definition in sysreg.h for
other reasons.
This is a bit of a maintenance headache, and the reasons for the
_el*() accessors working the way they do is a bit historical.
This patch gets rid of the shadow sysreg definitions in
<asm/kvm_hyp.h>, converts the _el*() accessors to use the core
__msr_s/__mrs_s interface, and converts all call sites to use the
standard sysreg #define names (i.e., upper case, with SYS_ prefix).
This patch will conflict heavily anyway, so the opportunity
to clean up some bad whitespace in the context of the changes is
taken.
The change exposes a few system registers that have no sysreg.h
definition, due to msr_s/mrs_s being used in place of msr/mrs:
additions are made in order to fill in the gaps.
Signed-off-by: Dave Martin <Dave.Martin@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christoffer Dall <christoffer.dall@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Link: https://www.spinics.net/lists/kvm-arm/msg31717.html
[Rebased to v4.21-rc1]
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
[Rebased to v5.2-rc5, changelog updates]
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Add documentation for the newly defined firmware registers to save and
restore any vulnerability mitigation status.
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Reviewed-by: Steven Price <steven.price@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
KVM implements the firmware interface for mitigating cache speculation
vulnerabilities. Guests may use this interface to ensure mitigation is
active.
If we want to migrate such a guest to a host with a different support
level for those workarounds, migration might need to fail, to ensure that
critical guests don't loose their protection.
Introduce a way for userland to save and restore the workarounds state.
On restoring we do checks that make sure we don't downgrade our
mitigation level.
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Reviewed-by: Eric Auger <eric.auger@redhat.com>
Reviewed-by: Steven Price <steven.price@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Recent commits added the explicit notion of "workaround not required" to
the state of the Spectre v2 (aka. BP_HARDENING) workaround, where we
just had "needed" and "unknown" before.
Export this knowledge to the rest of the kernel and enhance the existing
kvm_arm_harden_branch_predictor() to report this new state as well.
Export this new state to guests when they use KVM's firmware interface
emulation.
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Reviewed-by: Steven Price <steven.price@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
ARMv8 provides support for chained PMU counters, where an event type
of 0x001E is set for odd-numbered counters, the event counter will
increment by one for each overflow of the preceding even-numbered
counter. Let's emulate this in KVM by creating a 64 bit perf counter
when a user chains two emulated counters together.
For chained events we only support generating an overflow interrupt
on the high counter. We use the attributes of the low counter to
determine the attributes of the perf event.
Suggested-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Andrew Murray <andrew.murray@arm.com>
Reviewed-by: Julien Thierry <julien.thierry@arm.com>
Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
We currently use pmc->bitmask to determine the width of the pmc - however
it's superfluous as the pmc index already describes if the pmc is a cycle
counter or event counter. The architecture clearly describes the widths of
these counters.
Let's remove the bitmask to simplify the code.
Signed-off-by: Andrew Murray <andrew.murray@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
The perf event sample_period is currently set based upon the current
counter value, when PMXEVTYPER is written to and the perf event is created.
However the user may choose to write the type before the counter value in
which case sample_period will be set incorrectly. Let's instead decouple
event creation from PMXEVTYPER and (re)create the event in either
suitation.
Signed-off-by: Andrew Murray <andrew.murray@arm.com>
Reviewed-by: Julien Thierry <julien.thierry@arm.com>
Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Let's reduce code duplication by extracting common code to its own
function.
Signed-off-by: Andrew Murray <andrew.murray@arm.com>
Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
The kvm_pmu_{enable/disable}_counter functions can enable/disable
multiple counters at once as they operate on a bitmask. Let's
make this clearer by renaming the function.
Suggested-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Andrew Murray <andrew.murray@arm.com>
Reviewed-by: Julien Thierry <julien.thierry@arm.com>
Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
kvm-unit-tests were adjusted to match bare metal behavior, but KVM
itself was not doing what bare metal does; fix that.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
During __guest_exit() we need to consume any SError left pending by the
guest so it doesn't contaminate the host. With v8.2 we use the
ESB-instruction. For systems without v8.2, we use dsb+isb and unmask
SError. We do this on every guest exit.
Use the same dsb+isr_el1 trick, this lets us know if an SError is pending
after the dsb, allowing us to skip the isb and self-synchronising PSTATE
write if its not.
This means SError remains masked during KVM's world-switch, so any SError
that occurs during this time is reported by the host, instead of causing
a hyp-panic.
As we're benchmarking this code lets polish the layout. If you give gcc
likely()/unlikely() hints in an if() condition, it shuffles the generated
assembly so that the likely case is immediately after the branch. Lets
do the same here.
Signed-off-by: James Morse <james.morse@arm.com>
Changes since v2:
* Added isb after the dsb to prevent an early read
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
KVM consumes any SError that were pending during guest exit with a
dsb/isb and unmasking SError. It currently leaves SError unmasked for
the rest of world-switch.
This means any SError that occurs during this part of world-switch
will cause a hyp-panic. We'd much prefer it to remain pending until
we return to the host.
Signed-off-by: James Morse <james.morse@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Neoverse-N1 affected by #1349291 may report an Uncontained RAS Error
as Unrecoverable. The kernel's architecture code already considers
Unrecoverable errors as fatal as without kernel-first support no
further error-handling is possible.
Now that KVM attributes SError to the host/guest more precisely
the host's architecture code will always handle host errors that
become pending during world-switch.
Errors misclassified by this errata that affected the guest will be
re-injected to the guest as an implementation-defined SError, which can
be uncontained.
Until kernel-first support is implemented, no workaround is needed
for this issue.
Signed-off-by: James Morse <james.morse@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
SError that occur during world-switch's entry to the guest will be
accounted to the guest, as the exception is masked until we enter the
guest... but we want to attribute the SError as precisely as possible.
Reading DISR_EL1 before guest entry requires free registers, and using
ESB+DISR_EL1 to consume and read back the ESR would leave KVM holding
a host SError... We would rather leave the SError pending and let the
host take it once we exit world-switch. To do this, we need to defer
guest-entry if an SError is pending.
Read the ISR to see if SError (or an IRQ) is pending. If so fake an
exit. Place this check between __guest_enter()'s save of the host
registers, and restore of the guest's. SError that occur between
here and the eret into the guest must have affected the guest's
registers, which we can naturally attribute to the guest.
The dsb is needed to ensure any previous writes have been done before
we read ISR_EL1. On systems without the v8.2 RAS extensions this
doesn't give us anything as we can't contain errors, and the ESR bits
to describe the severity are all implementation-defined. Replace
this with a nop for these systems.
Signed-off-by: James Morse <james.morse@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
On systems with v8.2 we switch the 'vaxorcism' of guest SError with an
alternative sequence that uses the ESB-instruction, then reads DISR_EL1.
This saves the unmasking and remasking of asynchronous exceptions.
We do this after we've saved the guest registers and restored the
host's. Any SError that becomes pending due to this will be accounted
to the guest, when it actually occurred during host-execution.
Move the ESB-instruction as early as possible. Any guest SError
will become pending due to this ESB-instruction and then consumed to
DISR_EL1 before the host touches anything.
This lets us account for host/guest SError precisely on the guest
exit exception boundary.
Because the ESB-instruction now lands in the preamble section of
the vectors, we need to add it to the unpatched indirect vectors
too, and to any sequence that may be patched in over the top.
The ESB-instruction always lives in the head of the vectors,
to be before any memory write. Whereas the register-store always
lives in the tail.
Signed-off-by: James Morse <james.morse@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
The KVM indirect vectors support is a little complicated. Different CPUs
may use different exception vectors for KVM that are generated at boot.
Adding new instructions involves checking all the possible combinations
do the right thing.
To make changes here easier to review lets state what we expect of the
preamble:
1. The first vector run, must always run the preamble.
2. Patching the head or tail of the vector shouldn't remove
preamble instructions.
Today, this is easy as we only have one instruction in the preamble.
Change the unpatched tail of the indirect vector so that it always
runs this, regardless of patching.
Signed-off-by: James Morse <james.morse@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
The EL2 vector hardening feature causes KVM to generate vectors for
each type of CPU present in the system. The generated sequences already
do some of the early guest-exit work (i.e. saving registers). To avoid
duplication the generated vectors branch to the original vector just
after the preamble. This size is hard coded.
Adding new instructions to the HYP vector causes strange side effects,
which are difficult to debug as the affected code is patched in at
runtime.
Add KVM_VECTOR_PREAMBLE to tell kvm_patch_vector_branch() how big
the preamble is. The valid_vect macro can then validate this at
build time.
Reviewed-by: Julien Thierry <julien.thierry@arm.com>
Signed-off-by: James Morse <james.morse@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
The ESB-instruction is a nop on CPUs that don't implement the RAS
extensions. This lets us use it in places like the vectors without
having to use alternatives.
If someone disables CONFIG_ARM64_RAS_EXTN, this instruction still has
its RAS extensions behaviour, but we no longer read DISR_EL1 as this
register does depend on alternatives.
This could go wrong if we want to synchronize an SError from a KVM
guest. On a CPU that has the RAS extensions, but the KConfig option
was disabled, we consume the pending SError with no chance of ever
reading it.
Hide the ESB-instruction behind the CONFIG_ARM64_RAS_EXTN option,
outputting a regular nop if the feature has been disabled.
Reported-by: Julien Thierry <julien.thierry@arm.com>
Signed-off-by: James Morse <james.morse@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
According to section "Checks on Host Segment and Descriptor-Table
Registers" in Intel SDM vol 3C, the following checks are performed on
vmentry of nested guests:
- In the selector field for each of CS, SS, DS, ES, FS, GS and TR, the
RPL (bits 1:0) and the TI flag (bit 2) must be 0.
- The selector fields for CS and TR cannot be 0000H.
- The selector field for SS cannot be 0000H if the "host address-space
size" VM-exit control is 0.
- On processors that support Intel 64 architecture, the base-address
fields for FS, GS and TR must contain canonical addresses.
Signed-off-by: Krish Sadhukhan <krish.sadhukhan@oracle.com>
Reviewed-by: Karl Heubaum <karl.heubaum@oracle.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
KVM does not have 100% coverage of VMX consistency checks, i.e. some
checks that cause VM-Fail may only be detected by hardware during a
nested VM-Entry. In such a case, KVM must restore L1's state to the
pre-VM-Enter state as L2's state has already been loaded into KVM's
software model.
L1's CR3 and PDPTRs in particular are loaded from vmcs01.GUEST_*. But
when EPT is disabled, the associated fields hold KVM's shadow values,
not L1's "real" values. Fortunately, when EPT is disabled the PDPTRs
come from memory, i.e. are not cached in the VMCS. Which leaves CR3
as the sole anomaly.
A previously applied workaround to handle CR3 was to force nested early
checks if EPT is disabled:
commit 2b27924bb1 ("KVM: nVMX: always use early vmcs check when EPT
is disabled")
Forcing nested early checks is undesirable as doing so adds hundreds of
cycles to every nested VM-Entry. Rather than take this performance hit,
handle CR3 by overwriting vmcs01.GUEST_CR3 with L1's CR3 during nested
VM-Entry when EPT is disabled *and* nested early checks are disabled.
By stuffing vmcs01.GUEST_CR3, nested_vmx_restore_host_state() will
naturally restore the correct vcpu->arch.cr3 from vmcs01.GUEST_CR3.
These shenanigans work because nested_vmx_restore_host_state() does a
full kvm_mmu_reset_context(), i.e. unloads the current MMU, which
guarantees vmcs01.GUEST_CR3 will be rewritten with a new shadow CR3
prior to re-entering L1.
vcpu->arch.root_mmu.root_hpa is set to INVALID_PAGE via:
nested_vmx_restore_host_state() ->
kvm_mmu_reset_context() ->
kvm_mmu_unload() ->
kvm_mmu_free_roots()
kvm_mmu_unload() has WARN_ON(root_hpa != INVALID_PAGE), i.e. we can bank
on 'root_hpa == INVALID_PAGE' unless the implementation of
kvm_mmu_reset_context() is changed.
On the way into L1, VMCS.GUEST_CR3 is guaranteed to be written (on a
successful entry) via:
vcpu_enter_guest() ->
kvm_mmu_reload() ->
kvm_mmu_load() ->
kvm_mmu_load_cr3() ->
vmx_set_cr3()
Stuff vmcs01.GUEST_CR3 if and only if nested early checks are disabled
as a "late" VM-Fail should never happen win that case (KVM WARNs), and
the conditional write avoids the need to restore the correct GUEST_CR3
when nested_vmx_check_vmentry_hw() fails.
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Message-Id: <20190607185534.24368-1-sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Note that in such a case it is quite likely that KVM will BUG_ON
in __pte_list_remove when the VM is closed. However, there is no
immediate risk of memory corruption in the host so a WARN_ON is
enough and it lets you gather traces for debugging.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
After the previous patch, the low bits of the gfn are masked in
both FNAME(fetch) and __direct_map, so we do not need to clear them
in transparent_hugepage_adjust.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
These two functions are basically doing the same thing through
kvm_mmu_get_page, link_shadow_page and mmu_set_spte; yet, for historical
reasons, their code looks very different. This patch tries to take the
best of each and make them very similar, so that it is easy to understand
changes that apply to both of them.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Release the page at the call-site where it was originally acquired.
This makes the exit code cleaner for most call sites, since they
do not need to duplicate code between success and the failure
label.
Signed-off-by: Junaid Shahid <junaids@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
The has_leaf_count member was originally added for KVM's paravirtualization
CPUID leaves. However, since then the leaf count _has_ been added to those
leaves as well, so we can drop that special case.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
do_cpuid_1_ent does not do the entire processing for a CPUID entry, it
only retrieves the host's values. Rename it to match reality.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
do_cpuid_1_ent is typically called in two places by __do_cpuid_func
for CPUID functions that have subleafs. Both places have to set
the KVM_CPUID_FLAG_SIGNIFCANT_INDEX. Set that flag, and
KVM_CPUID_FLAG_STATEFUL_FUNC as well, directly in do_cpuid_1_ent.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
CPUID function 7 has multiple subleafs. Instead of having nested
switch statements, move the logic to filter supported features to
a separate function, and call it for each subleaf.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Rename it as well as __do_cpuid_ent and __do_cpuid_ent_emulated to have
"func" in its name, and drop the index parameter which is always 0.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
The trailing newlines will lead to extra newlines in the trace file
which looks like the following output, so remove it.
qemu-system-x86-15695 [002] ...1 15774.839240: kvm_hv_timer_state: vcpu_id 0 hv_timer 1
qemu-system-x86-15695 [002] ...1 15774.839309: kvm_hv_timer_state: vcpu_id 0 hv_timer 1
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Allow testing code for old processors that lack the next RIP save
feature, by disabling usage of the next_rip field.
Nested hypervisors however get the feature unconditionally.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This bit is purely advisory. Passing it through to the guest indicates
that the virtual processor, like the physical processor, prefers that
STIBP is only set once during boot and not changed.
Signed-off-by: Jim Mattson <jmattson@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
When L0 is executing handle_invept(), the TDP MMU is active. Emulating
an L1 INVEPT does require synchronizing the appropriate shadow EPT
root(s), but a call to kvm_mmu_sync_roots in this context won't do
that. Similarly, the hardware TLB and paging-structure-cache entries
associated with the appropriate shadow EPT root(s) must be flushed,
but requesting a TLB_FLUSH from this context won't do that either.
How did this ever work? KVM always does a sync_roots and TLB flush (in
the correct context) when transitioning from L1 to L2. That isn't the
best choice for nested VM performance, but it effectively papers over
the mistakes here.
Remove the unnecessary operations and leave a comment to try to do
better in the future.
Reported-by: Junaid Shahid <junaids@google.com>
Fixes: bfd0a56b90 ("nEPT: Nested INVEPT")
Cc: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
Cc: Nadav Har'El <nyh@il.ibm.com>
Cc: Jun Nakajima <jun.nakajima@intel.com>
Cc: Xinhao Xu <xinhao.xu@intel.com>
Cc: Yang Zhang <yang.z.zhang@Intel.com>
Cc: Gleb Natapov <gleb@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by Peter Shier <pshier@google.com>
Reviewed-by: Junaid Shahid <junaids@google.com>
Signed-off-by: Jim Mattson <jmattson@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Expose PV_SCHED_YIELD feature bit to guest, the guest can check this
feature bit before using paravirtualized sched yield.
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Cc: Liran Alon <liran.alon@oracle.com>
Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
The target vCPUs are in runnable state after vcpu_kick and suitable
as a yield target. This patch implements the sched yield hypercall.
17% performance increasement of ebizzy benchmark can be observed in an
over-subscribe environment. (w/ kvm-pv-tlb disabled, testing TLB flush
call-function IPI-many since call-function is not easy to be trigged
by userspace workload).
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Cc: Liran Alon <liran.alon@oracle.com>
Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
When sending a call-function IPI-many to vCPUs, yield if any of
the IPI target vCPUs was preempted, we just select the first
preempted target vCPU which we found since the state of target
vCPUs can change underneath and to avoid race conditions.
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Cc: Liran Alon <liran.alon@oracle.com>
Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
When Enlightened VMCS is in use, it is valid to do VMCLEAR and,
according to TLFS, this should "transition an enlightened VMCS from the
active to the non-active state". It is, however, wrong to assume that
it is only valid to do VMCLEAR for the eVMCS which is currently active
on the vCPU performing VMCLEAR.
Currently, the logic in handle_vmclear() is broken: in case, there is no
active eVMCS on the vCPU doing VMCLEAR we treat the argument as a 'normal'
VMCS and kvm_vcpu_write_guest() to the 'launch_state' field irreversibly
corrupts the memory area.
So, in case the VMCLEAR argument is not the current active eVMCS on the
vCPU, how can we know if the area it is pointing to is a normal or an
enlightened VMCS?
Thanks to the bug in Hyper-V (see commit 72aeb60c52 ("KVM: nVMX: Verify
eVMCS revision id match supported eVMCS version on eVMCS VMPTRLD")) we can
not, the revision can't be used to distinguish between them. So let's
assume it is always enlightened in case enlightened vmentry is enabled in
the assist page. Also, check if vmx->nested.enlightened_vmcs_enabled to
minimize the impact for 'unenlightened' workloads.
Fixes: b8bbab928f ("KVM: nVMX: implement enlightened VMPTRLD and VMCLEAR")
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Paolo Bonzini