Consider the case L1 had a IRQ/NMI event until it executed
VMLAUNCH/VMRESUME which wasn't delivered because it was disallowed
(e.g. interrupts disabled). When L1 executes VMLAUNCH/VMRESUME,
L0 needs to evaluate if this pending event should cause an exit from
L2 to L1 or delivered directly to L2 (e.g. In case L1 don't intercept
EXTERNAL_INTERRUPT).

Usually this would be handled by L0 requesting a IRQ/NMI window
by setting VMCS accordingly. However, this setting was done on
VMCS01 and now VMCS02 is active instead. Thus, when L1 executes
VMLAUNCH/VMRESUME we force L0 to perform pending event evaluation by
requesting a KVM_REQ_EVENT.

Note that above scenario exists when L1 KVM is about to enter L2 but
requests an "immediate-exit". As in this case, L1 will
disable-interrupts and then send a self-IPI before entering L2.
Reviewed-by: NNikita Leshchenko <nikita.leshchenko@oracle.com>
Co-developed-by: NSean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: NSean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: NLiran Alon <liran.alon@oracle.com>
Signed-off-by: NRadim Krčmář <rkrcmar@redhat.com>

kvm_unmap_hva is long gone, and we only have kvm_unmap_hva_range to
deal with. Drop the now obsolete code.

Fixes: fb1522e0 ("KVM: update to new mmu_notifier semantic v2")
Cc: James Hogan <jhogan@kernel.org>
Reviewed-by: NPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: NMarc Zyngier <marc.zyngier@arm.com>
Signed-off-by: NChristoffer Dall <christoffer.dall@arm.com>

Allowing x86_emulate_instruction() to be called directly has led to
subtle bugs being introduced, e.g. not setting EMULTYPE_NO_REEXECUTE
in the emulation type.  While most of the blame lies on re-execute
being opt-out, exporting x86_emulate_instruction() also exposes its
cr2 parameter, which may have contributed to commit d391f120
("x86/kvm/vmx: do not use vm-exit instruction length for fast MMIO
when running nested") using x86_emulate_instruction() instead of
emulate_instruction() because "hey, I have a cr2!", which in turn
introduced its EMULTYPE_NO_REEXECUTE bug.
Signed-off-by: NSean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: NRadim Krčmář <rkrcmar@redhat.com>

Lack of the kvm_ prefix gives the impression that it's a VMX or SVM
specific function, and there's no conflict that prevents adding the
kvm_ prefix.
Signed-off-by: NSean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: NRadim Krčmář <rkrcmar@redhat.com>

Commit a6f177ef ("KVM: Reenter guest after emulation failure if
due to access to non-mmio address") added reexecute_instruction() to
handle the scenario where two (or more) vCPUS race to write a shadowed
page, i.e. reexecute_instruction() is intended to return true if and
only if the instruction being emulated was accessing a shadowed page.
As L0 is only explicitly shadowing L1 tables, an emulation failure of
a nested VM instruction cannot be due to a race to write a shadowed
page and so should never be re-executed.

This fixes an issue where an "MMIO" emulation failure[1] in L2 is all
but guaranteed to result in an infinite loop when TDP is enabled.
Because "cr2" is actually an L2 GPA when TDP is enabled, calling
kvm_mmu_gva_to_gpa_write() to translate cr2 in the non-direct mapped
case (L2 is never direct mapped) will almost always yield UNMAPPED_GVA
and cause reexecute_instruction() to immediately return true.  The
!mmio_info_in_cache() check in kvm_mmu_page_fault() doesn't catch this
case because mmio_info_in_cache() returns false for a nested MMU (the
MMIO caching currently handles L1 only, e.g. to cache nested guests'
GPAs we'd have to manually flush the cache when switching between
VMs and when L1 updated its page tables controlling the nested guest).

Way back when, commit 68be0803 ("KVM: x86: never re-execute
instruction with enabled tdp") changed reexecute_instruction() to
always return false when using TDP under the assumption that KVM would
only get into the emulator for MMIO.  Commit 95b3cf69 ("KVM: x86:
let reexecute_instruction work for tdp") effectively reverted that
behavior in order to handle the scenario where emulation failed due to
an access from L1 to the shadow page tables for L2, but it didn't
account for the case where emulation failed in L2 with TDP enabled.

All of the above logic also applies to retry_instruction(), added by
commit 1cb3f3ae ("KVM: x86: retry non-page-table writing
instructions").  An indefinite loop in retry_instruction() should be
impossible as it protects against retrying the same instruction over
and over, but it's still correct to not retry an L2 instruction in
the first place.

Fix the immediate issue by adding a check for a nested guest when
determining whether or not to allow retry in kvm_mmu_page_fault().
In addition to fixing the immediate bug, add WARN_ON_ONCE in the
retry functions since they are not designed to handle nested cases,
i.e. they need to be modified even if there is some scenario in the
future where we want to allow retrying a nested guest.

[1] This issue was encountered after commit 3a2936de ("kvm: mmu:
    Don't expose private memslots to L2") changed the page fault path
    to return KVM_PFN_NOSLOT when translating an L2 access to a
    prive memslot.  Returning KVM_PFN_NOSLOT is semantically correct
    when we want to hide a memslot from L2, i.e. there effectively is
    no defined memory region for L2, but it has the unfortunate side
    effect of making KVM think the GFN is a MMIO page, thus triggering
    emulation.  The failure occurred with in-development code that
    deliberately exposed a private memslot to L2, which L2 accessed
    with an instruction that is not emulated by KVM.

Fixes: 95b3cf69 ("KVM: x86: let reexecute_instruction work for tdp")
Fixes: 1cb3f3ae ("KVM: x86: retry non-page-table writing instructions")
Signed-off-by: NSean Christopherson <sean.j.christopherson@intel.com>
Cc: Jim Mattson <jmattson@google.com>
Cc: Krish Sadhukhan <krish.sadhukhan@oracle.com>
Cc: Xiao Guangrong <xiaoguangrong@tencent.com>
Cc: stable@vger.kernel.org
Signed-off-by: NRadim Krčmář <rkrcmar@redhat.com>

Effectively force kvm_mmu_page_fault() to opt-in to allowing retry to
make it more obvious when and why it allows emulation to be retried.
Previously this approach was less convenient due to retry and
re-execute behavior being controlled by separate flags that were also
inverted in their implementations (opt-in versus opt-out).
Suggested-by: NPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: NSean Christopherson <sean.j.christopherson@intel.com>
Cc: stable@vger.kernel.org
Signed-off-by: NRadim Krčmář <rkrcmar@redhat.com>

retry_instruction() and reexecute_instruction() are a package deal,
i.e. there is no scenario where one is allowed and the other is not.
Merge their controlling emulation type flags to enforce this in code.
Name the combined flag EMULTYPE_ALLOW_RETRY to make it abundantly
clear that we are allowing re{try,execute} to occur, as opposed to
explicitly requesting retry of a previously failed instruction.
Signed-off-by: NSean Christopherson <sean.j.christopherson@intel.com>
Cc: stable@vger.kernel.org
Signed-off-by: NRadim Krčmář <rkrcmar@redhat.com>

Re-execution of an instruction after emulation decode failure is
intended to be used only when emulating shadow page accesses.  Invert
the flag to make allowing re-execution opt-in since that behavior is
by far in the minority.
Signed-off-by: NSean Christopherson <sean.j.christopherson@intel.com>
Cc: stable@vger.kernel.org
Signed-off-by: NRadim Krčmář <rkrcmar@redhat.com>

Re-execution after an emulation decode failure is only intended to
handle a case where two or vCPUs race to write a shadowed page, i.e.
we should never re-execute an instruction as part of RSM emulation.

Add a new helper, kvm_emulate_instruction_from_buffer(), to support
emulating from a pre-defined buffer.  This eliminates the last direct
call to x86_emulate_instruction() outside of kvm_mmu_page_fault(),
which means x86_emulate_instruction() can be unexported in a future
patch.

Fixes: 7607b717 ("KVM: SVM: install RSM intercept")
Cc: Brijesh Singh <brijesh.singh@amd.com>
Signed-off-by: NSean Christopherson <sean.j.christopherson@intel.com>
Cc: stable@vger.kernel.org
Signed-off-by: NRadim Krčmář <rkrcmar@redhat.com>

Re-execution after an emulation decode failure is only intended to
handle a case where two or vCPUs race to write a shadowed page, i.e.
we should never re-execute an instruction as part of MMIO emulation.
As handle_ept_misconfig() is only used for MMIO emulation, it should
pass EMULTYPE_NO_REEXECUTE when using the emulator to skip an instr
in the fast-MMIO case where VM_EXIT_INSTRUCTION_LEN is invalid.

And because the cr2 value passed to x86_emulate_instruction() is only
destined for use when retrying or reexecuting, we can simply call
emulate_instruction().

Fixes: d391f120 ("x86/kvm/vmx: do not use vm-exit instruction length
                      for fast MMIO when running nested")
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: NSean Christopherson <sean.j.christopherson@intel.com>
Cc: stable@vger.kernel.org
Signed-off-by: NRadim Krčmář <rkrcmar@redhat.com>

Variable dst_vaddr_end is being assigned but is never used hence it is
redundant and can be removed.

Cleans up clang warning:
variable 'dst_vaddr_end' set but not used [-Wunused-but-set-variable]
Signed-off-by: NColin Ian King <colin.king@canonical.com>
Signed-off-by: NRadim Krčmář <rkrcmar@redhat.com>

nested_run_pending is set 20 lines above and check_vmentry_prereqs()/
check_vmentry_postreqs() don't seem to be resetting it (the later, however,
checks it).
Signed-off-by: NVitaly Kuznetsov <vkuznets@redhat.com>
Reviewed-by: NPaolo Bonzini <pbonzini@redhat.com>
Reviewed-by: NJim Mattson <jmattson@google.com>
Reviewed-by: NEduardo Valentin <eduval@amazon.com>
Reviewed-by: NKrish Sadhukhan <krish.sadhukhan@oracle.com>
Signed-off-by: NRadim Krčmář <rkrcmar@redhat.com>

There are several blockable mmu notifiers which might sleep in
mmu_notifier_invalidate_range_start and that is a problem for the
oom_reaper because it needs to guarantee a forward progress so it cannot
depend on any sleepable locks.

Currently we simply back off and mark an oom victim with blockable mmu
notifiers as done after a short sleep.  That can result in selecting a new
oom victim prematurely because the previous one still hasn't torn its
memory down yet.

We can do much better though.  Even if mmu notifiers use sleepable locks
there is no reason to automatically assume those locks are held.  Moreover
majority of notifiers only care about a portion of the address space and
there is absolutely zero reason to fail when we are unmapping an unrelated
range.  Many notifiers do really block and wait for HW which is harder to
handle and we have to bail out though.

This patch handles the low hanging fruit.
__mmu_notifier_invalidate_range_start gets a blockable flag and callbacks
are not allowed to sleep if the flag is set to false.  This is achieved by
using trylock instead of the sleepable lock for most callbacks and
continue as long as we do not block down the call chain.

I think we can improve that even further because there is a common pattern
to do a range lookup first and then do something about that.  The first
part can be done without a sleeping lock in most cases AFAICS.

The oom_reaper end then simply retries if there is at least one notifier
which couldn't make any progress in !blockable mode.  A retry loop is
already implemented to wait for the mmap_sem and this is basically the
same thing.

The simplest way for driver developers to test this code path is to wrap
userspace code which uses these notifiers into a memcg and set the hard
limit to hit the oom.  This can be done e.g.  after the test faults in all
the mmu notifier managed memory and set the hard limit to something really
small.  Then we are looking for a proper process tear down.

[akpm@linux-foundation.org: coding style fixes]
[akpm@linux-foundation.org: minor code simplification]
Link: http://lkml.kernel.org/r/20180716115058.5559-1-mhocko@kernel.orgSigned-off-by: NMichal Hocko <mhocko@suse.com>
Acked-by: Christian König <christian.koenig@amd.com> # AMD notifiers
Acked-by: Leon Romanovsky <leonro@mellanox.com> # mlx and umem_odp
Reported-by: NDavid Rientjes <rientjes@google.com>
Cc: "David (ChunMing) Zhou" <David1.Zhou@amd.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: David Airlie <airlied@linux.ie>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: Doug Ledford <dledford@redhat.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Mike Marciniszyn <mike.marciniszyn@intel.com>
Cc: Dennis Dalessandro <dennis.dalessandro@intel.com>
Cc: Sudeep Dutt <sudeep.dutt@intel.com>
Cc: Ashutosh Dixit <ashutosh.dixit@intel.com>
Cc: Dimitri Sivanich <sivanich@sgi.com>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: "Jérôme Glisse" <jglisse@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Felix Kuehling <felix.kuehling@amd.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Two bug fixes:

1) missing entries in the l1d_param array; this can cause a host crash
if an access attempts to reach the missing entry. Future-proof the get
function against any overflows as well.  However, the two entries
VMENTER_L1D_FLUSH_EPT_DISABLED and VMENTER_L1D_FLUSH_NOT_REQUIRED must
not be accepted by the parse function, so disable them there.

2) invalid values must be rejected even if the CPU does not have the
bug, so test for them before checking boot_cpu_has(X86_BUG_L1TF)

... and a small refactoring, since the .cmd field is redundant with
the index in the array.
Reported-by: NBandan Das <bsd@redhat.com>
Cc: stable@vger.kernel.org
Fixes: a7b9020bSigned-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Mikhail reported the following lockdep splat:

WARNING: possible irq lock inversion dependency detected
CPU 0/KVM/10284 just changed the state of lock:
  000000000d538a88 (&st->lock){+...}, at:
  speculative_store_bypass_update+0x10b/0x170

but this lock was taken by another, HARDIRQ-safe lock
in the past:

(&(&sighand->siglock)->rlock){-.-.}

   and interrupts could create inverse lock ordering between them.

Possible interrupt unsafe locking scenario:

    CPU0                    CPU1
    ----                    ----
   lock(&st->lock);
                           local_irq_disable();
                           lock(&(&sighand->siglock)->rlock);
                           lock(&st->lock);
    <Interrupt>
     lock(&(&sighand->siglock)->rlock);
     *** DEADLOCK ***

The code path which connects those locks is:

   speculative_store_bypass_update()
   ssb_prctl_set()
   do_seccomp()
   do_syscall_64()

In svm_vcpu_run() speculative_store_bypass_update() is called with
interupts enabled via x86_virt_spec_ctrl_set_guest/host().

This is actually a false positive, because GIF=0 so interrupts are
disabled even if IF=1; however, we can easily move the invocations of
x86_virt_spec_ctrl_set_guest/host() into the interrupt disabled region to
cure it, and it's a good idea to keep the GIF=0/IF=1 area as small
and self-contained as possible.

Fixes: 1f50ddb4 ("x86/speculation: Handle HT correctly on AMD")
Reported-by: NMikhail Gavrilov <mikhail.v.gavrilov@gmail.com>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Tested-by: NMikhail Gavrilov <mikhail.v.gavrilov@gmail.com>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Borislav Petkov <bp@suse.de>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: kvm@vger.kernel.org
Cc: x86@kernel.org
Cc: stable@vger.kernel.org
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Virtualization of Intel SGX depends on Enclave Page Cache (EPC)
management that is not yet available in the kernel, i.e. KVM support
for exposing SGX to a guest cannot be added until basic support
for SGX is upstreamed, which is a WIP[1].

Until SGX is properly supported in KVM, ensure a guest sees expected
behavior for ENCLS, i.e. all ENCLS #UD.  Because SGX does not have a
true software enable bit, e.g. there is no CR4.SGXE bit, the ENCLS
instruction can be executed[1] by the guest if SGX is supported by the
system.  Intercept all ENCLS leafs (via the ENCLS- exiting control and
field) and unconditionally inject #UD.

[1] https://www.spinics.net/lists/kvm/msg171333.html or
    https://lkml.org/lkml/2018/7/3/879

[2] A guest can execute ENCLS in the sense that ENCLS will not take
    an immediate #UD, but no ENCLS will ever succeed in a guest
    without explicit support from KVM (map EPC memory into the guest),
    unless KVM has a *very* egregious bug, e.g. accidentally mapped
    EPC memory into the guest SPTEs.  In other words this patch is
    needed only to prevent the guest from seeing inconsistent behavior,
    e.g. #GP (SGX not enabled in Feature Control MSR) or #PF (leaf
    operand(s) does not point at EPC memory) instead of #UD on ENCLS.
    Intercepting ENCLS is not required to prevent the guest from truly
    utilizing SGX.
Signed-off-by: NSean Christopherson <sean.j.christopherson@intel.com>
Message-Id: <20180814163334.25724-3-sean.j.christopherson@intel.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Substitute spaces with tab. No functional changes.
Signed-off-by: NYi Wang <wang.yi59@zte.com.cn>
Reviewed-by: NJiang Biao <jiang.biao2@zte.com.cn>
Message-Id: <1534398159-48509-1-git-send-email-wang.yi59@zte.com.cn>
Cc: stable@vger.kernel.org # L1TF
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Removing one of the two accesses of the maxphyaddr variable led to
a harmless warning:

arch/x86/kvm/x86.c: In function 'kvm_set_mmio_spte_mask':
arch/x86/kvm/x86.c:6563:6: error: unused variable 'maxphyaddr' [-Werror=unused-variable]

Removing the #ifdef seems to be the nicest workaround, as it
makes the code look cleaner than adding another #ifdef.

Fixes: 28a1f3ac ("kvm: x86: Set highest physical address bits in non-present/reserved SPTEs")
Signed-off-by: NArnd Bergmann <arnd@arndb.de>
Cc: stable@vger.kernel.org # L1TF
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

These are already defined higher up in the file.

Fixes: 7db92e16 ("x86/kvm: Move l1tf setup function")
Signed-off-by: NJosh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/d7ca03ae210d07173452aeed85ffe344301219a5.1534253536.git.jpoimboe@redhat.com

Always set the 5 upper-most supported physical address bits to 1 for SPTEs
that are marked as non-present or reserved, to make them unusable for
L1TF attacks from the guest. Currently, this just applies to MMIO SPTEs.
(We do not need to mark PTEs that are completely 0 as physical page 0
is already reserved.)

This allows mitigation of L1TF without disabling hyper-threading by using
shadow paging mode instead of EPT.
Signed-off-by: NJunaid Shahid <junaids@google.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Remove open-coded uses of set instructions to use CC_SET()/CC_OUT() in
arch/x86/kvm/vmx.c.
Signed-off-by: NUros Bizjak <ubizjak@gmail.com>
[Mark error paths as unlikely while touching this. - Paolo]
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Using hypercall to send IPIs by one vmexit instead of one by one for
xAPIC/x2APIC physical mode and one vmexit per-cluster for x2APIC cluster
mode. Intel guest can enter x2apic cluster mode when interrupt remmaping
is enabled in qemu, however, latest AMD EPYC still just supports xapic
mode which can get great improvement by Exit-less IPIs. This patchset
lets a guest send multicast IPIs, with at most 128 destinations per
hypercall in 64-bit mode and 64 vCPUs per hypercall in 32-bit mode.

Hardware: Xeon Skylake 2.5GHz, 2 sockets, 40 cores, 80 threads, the VM
is 80 vCPUs, IPI microbenchmark(https://lkml.org/lkml/2017/12/19/141):

x2apic cluster mode, vanilla

 Dry-run:                         0,            2392199 ns
 Self-IPI:                  6907514,           15027589 ns
 Normal IPI:              223910476,          251301666 ns
 Broadcast IPI:                   0,         9282161150 ns
 Broadcast lock:                  0,         8812934104 ns

x2apic cluster mode, pv-ipi

 Dry-run:                         0,            2449341 ns
 Self-IPI:                  6720360,           15028732 ns
 Normal IPI:              228643307,          255708477 ns
 Broadcast IPI:                   0,         7572293590 ns  => 22% performance boost
 Broadcast lock:                  0,         8316124651 ns

x2apic physical mode, vanilla

 Dry-run:                         0,            3135933 ns
 Self-IPI:                  8572670,           17901757 ns
 Normal IPI:              226444334,          255421709 ns
 Broadcast IPI:                   0,        19845070887 ns
 Broadcast lock:                  0,        19827383656 ns

x2apic physical mode, pv-ipi

 Dry-run:                         0,            2446381 ns
 Self-IPI:                  6788217,           15021056 ns
 Normal IPI:              219454441,          249583458 ns
 Broadcast IPI:                   0,         7806540019 ns  => 154% performance boost
 Broadcast lock:                  0,         9143618799 ns

Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: NWanpeng Li <wanpengli@tencent.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

X86_CR4_OSXSAVE check belongs to sregs check and so move into
kvm_valid_sregs().
Signed-off-by: NLan Tianyu <Tianyu.Lan@microsoft.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Considering the fact that the pae_root shadow is not needed when
tdp is in use, skip the pae_root shadow page allocation to allow
mmu creation even not being able to obtain memory from DMA32
zone when particular cgroup cpuset.mems or mempolicy control is
applied.
Signed-off-by: NLiang Chen <liangchen.linux@gmail.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

mmu_set_spte() flushes remote tlbs for drop_parent_pte/drop_spte()
and set_spte() separately. This may introduce redundant flush. This
patch is to combine these flushes and check flush request after
calling set_spte().
Signed-off-by: NLan Tianyu <Tianyu.Lan@microsoft.com>
Reviewed-by: NJunaid Shahid <junaids@google.com>
Reviewed-by: NXiao Guangrong <xiaoguangrong@tencent.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

The host's FS.base and GS.base rarely change, e.g. ~0.1% of host/guest
swaps on my system.  Cache the last value written to the VMCS and skip
the VMWRITE to the associated VMCS fields when loading host state if
the value hasn't changed since the last VMWRITE.
Signed-off-by: NSean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

On a 64-bit host, FS.sel and GS.sel are all but guaranteed to be 0,
which in turn means they'll rarely change.  Skip the VMWRITE for the
associated VMCS fields when loading host state if the selector hasn't
changed since the last VMWRITE.
Signed-off-by: NSean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

The HOST_{FS,GS}_BASE fields are guaranteed to be written prior to
VMENTER, by way of vmx_prepare_switch_to_guest().  Initialize the
fields to zero for 64-bit kernels instead of pulling the base values
from their respective MSRs.  In addition to eliminating two RDMSRs,
vmx_prepare_switch_to_guest() can safely assume the initial value of
the fields is zero in all cases.
Signed-off-by: NSean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Make host_state a property of a loaded_vmcs so that it can be
used as a cache of the VMCS fields, e.g. to lazily VMWRITE the
corresponding VMCS field.  Treating host_state as a cache does
not work if it's not VMCS specific as the cache would become
incoherent when switching between vmcs01 and vmcs02.

Move vmcs_host_cr3 and vmcs_host_cr4 into host_state.

Explicitly zero out host_state when allocating a new VMCS for a
loaded_vmcs.  Unlike the pre-existing vmcs_host_cr{3,4} usage,
the segment information is not guaranteed to be (re)initialized
when running a new nested VMCS, e.g. HOST_FS_BASE is not written
in vmx_set_constant_host_state().
Signed-off-by: NSean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Remove fs_reload_needed and gs_ldt_reload_needed from host_state
and instead compute whether we need to reload various state at
the time we actually do the reload.  The state that is tracked
by the *_reload_needed variables is not any more volatile than
the trackers themselves.
Signed-off-by: NSean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

prepare_vmcs02() has an odd comment that says certain fields are
"not in vmcs02".  AFAICT the intent of the comment is to document
that various VMCS fields are not handled by prepare_vmcs02(),
e.g. HOST_{FS,GS}_{BASE,SELECTOR}.  While technically true, the
comment is misleading, e.g. it can lead the reader to think that
KVM never writes those fields to vmcs02.

Remove the comment altogether as the handling of FS and GS is
not specific to nested VMX, and GUEST_PML_INDEX has been written
by prepare_vmcs02() since commit "4e59516a (kvm: vmx: ensure
VMCS is current while enabling PML)"
Signed-off-by: NSean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Now that the vmx_load_host_state() wrapper is gone, i.e. the only
time we call the core functions is when we're actually about to
switch between guest/host, rename the functions that handle lazy
state switching to vmx_prepare_switch_to_{guest,host}_state() to
better document the full extent of their functionality.
Signed-off-by: NSean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

When lazy save/restore of MSR_KERNEL_GS_BASE was introduced[1], the
MSR was intercepted in all modes and was only restored for the host
when the guest is in 64-bit mode.  So at the time, going through the
full host restore prior to accessing MSR_KERNEL_GS_BASE was necessary
to load host state and was not a significant waste of cycles.

Later, MSR_KERNEL_GS_BASE interception was disabled for a 64-bit
guest[2], and then unconditionally saved/restored for the host[3].
As a result, loading full host state is overkill for accesses to
MSR_KERNEL_GS_BASE, and completely unnecessary when the guest is
not in 64-bit mode.

Add a dedicated utility to read/write the guest's MSR_KERNEL_GS_BASE
(outside of the save/restore flow) to minimize the overhead incurred
when accessing the MSR.  When setting EFER, only decache the MSR if
the new EFER will disable long mode.

Removing out-of-band usage of vmx_load_host_state() also eliminates,
or at least reduces, potential corner cases in its usage, which in
turn will (hopefuly) make it easier to reason about future changes
to the save/restore flow, e.g. optimization of saving host state.

[1] commit 44ea2b17 ("KVM: VMX: Move MSR_KERNEL_GS_BASE out of the vmx
                                    autoload msr area")
[2] commit 5897297b ("KVM: VMX: Don't intercept MSR_KERNEL_GS_BASE")
[3] commit c8770e7b ("KVM: VMX: Fix host userspace gsbase corruption")
Signed-off-by: NSean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Using 'struct loaded_vmcs*' to track whether the CPU registers
contain host or guest state kills two birds with one stone.

  1. The (effective) boolean host_state.loaded is poorly named.
     It does not track whether or not host state is loaded into
     the CPU registers (which most readers would expect), but
     rather tracks if host state has been saved AND guest state
     is loaded.

  2. Using a loaded_vmcs pointer provides a more robust framework
     for the optimized guest/host state switching, especially when
     consideration per-VMCS enhancements.  To that end, WARN_ONCE
     if we try to switch to host state with a different VMCS than
     was last used to save host state.

Resolve an occurrence of the new WARN by setting loaded_vmcs after
the call to vmx_vcpu_put() in vmx_switch_vmcs().
Signed-off-by: NSean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Use local variables in vmx_save_host_state() to temporarily track
the selector and base values for FS and GS, and reorganize the
code so that the 64-bit vs 32-bit portions are contained within
a single #ifdef.  This refactoring paves the way for future patches
to modify the updating of VMCS state with minimal changes to the
code, and (hopefully) simplifies resolving a likely conflict with
another in-flight patch[1] by being the whipping boy for future
patches.

[1] https://www.spinics.net/lists/kvm/msg171647.htmlSigned-off-by: NSean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

When checking emulated VMX instructions for faults, the #UD for "IF
(not in VMX operation)" should take precedence over the #GP for "ELSIF
CPL > 0."
Suggested-by: NEric Northup <digitaleric@google.com>
Signed-off-by: NJim Mattson <jmattson@google.com>
Reviewed-by: NDavid Hildenbrand <david@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

The fault that should be raised for a privilege level violation is #GP
rather than #UD.

Fixes: 727ba748 ("kvm: nVMX: Enforce cpl=0 for VMX instructions")
Signed-off-by: NJim Mattson <jmattson@google.com>
Reviewed-by: NDavid Hildenbrand <david@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Register tlb_remote_flush callback for vmx when hyperv capability of
nested guest mapping flush is detected. The interface can help to
reduce overhead when flush ept table among vcpus for nested VM. The
tradition way is to send IPIs to all affected vcpus and executes
INVEPT on each vcpus. It will trigger several vmexits for IPI
and INVEPT emulation. Hyper-V provides such hypercall to do
flush for all vcpus and call the hypercall when all ept table
pointers of single VM are same.
Signed-off-by: NLan Tianyu <Tianyu.Lan@microsoft.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Merge check of "sp->role.cr4_pae != !!is_pae(vcpu))" and "vcpu->
arch.mmu.sync_page(vcpu, sp) == 0". kvm_mmu_prepare_zap_page()
is called under both these conditions.
Signed-off-by: NLan Tianyu <Tianyu.Lan@microsoft.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

It is a duplicate of X86_CR3_PCID_NOFLUSH. So just use that instead.
Signed-off-by: NJunaid Shahid <junaids@google.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>