The gs_index loading code uses the swapgs instruction to
switch to the user gs_base temporarily. This is unsave in an
lightweight exit-path in KVM on AMD because the
KERNEL_GS_BASE MSR is switches lazily. An NMI happening in
the critical path of load_gs_index may use the wrong GS_BASE
value then leading to unpredictable behavior, e.g. a
triple-fault.

This patch fixes the issue by making sure that load_gs_index
is called only with a valid KERNEL_GS_BASE value loaded in
KVM.
Signed-off-by: NJoerg Roedel <joerg.roedel@amd.com>
Signed-off-by: NAvi Kivity <avi@redhat.com>

For GRU and EPT, we need gup-fast to set referenced bit too (this is why
it's correct to return 0 when shadow_access_mask is zero, it requires
gup-fast to set the referenced bit).  qemu-kvm access already sets the
young bit in the pte if it isn't zero-copy, if it's zero copy or a shadow
paging EPT minor fault we relay on gup-fast to signal the page is in
use...

We also need to check the young bits on the secondary pagetables for NPT
and not nested shadow mmu as the data may never get accessed again by the
primary pte.

Without this closer accuracy, we'd have to remove the heuristic that
avoids collapsing hugepages in hugepage virtual regions that have not even
a single subpage in use.

->test_young is full backwards compatible with GRU and other usages that
don't have young bits in pagetables set by the hardware and that should
nuke the secondary mmu mappings when ->clear_flush_young runs just like
EPT does.

Removing the heuristic that checks the young bit in
khugepaged/collapse_huge_page completely isn't so bad either probably but
I thought it was worth it and this makes it reliable.
Signed-off-by: NAndrea Arcangeli <aarcange@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This should work for both hugetlbfs and transparent hugepages.

[akpm@linux-foundation.org: bring forward PageTransCompound() addition for bisectability]
Signed-off-by: NAndrea Arcangeli <aarcange@redhat.com>
Cc: Avi Kivity <avi@redhat.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

init_fpu() (which is indirectly called by the fpu switching code) assumes
it is in process context.  Rather than makeing init_fpu() use an atomic
allocation, which can cause a task to be killed, make sure the fpu is
already initialized when we enter the run loop.

KVM-Stable-Tag.
Reported-and-tested-by: NKirill A. Shutemov <kas@openvz.org>
Acked-by: NPekka Enberg <penberg@kernel.org>
Reviewed-by: NChristoph Lameter <cl@linux.com>
Signed-off-by: NAvi Kivity <avi@redhat.com>

VMX checks that base is equal segment shifted 4 bits left. Otherwise
guest entry fails.
Signed-off-by: NGleb Natapov <gleb@redhat.com>
Signed-off-by: NAvi Kivity <avi@redhat.com>

Move the operation of 'writable' to set_spte() to clean up code

[avi: remove unneeded booleanification]
Signed-off-by: NXiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Signed-off-by: NAvi Kivity <avi@redhat.com>

It only allows to audit one guest in the system since:
- 'audit_point' is a glob variable
- mmu_audit_disable() is called in kvm_mmu_destroy(), so audit is disabled
  after a guest exited

this patch fix those issues then allow to audit more guests at the same time
Signed-off-by: NXiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Signed-off-by: NAvi Kivity <avi@redhat.com>

Instead of syncing the guest cr3 every exit, which is expensince on vmx
with ept enabled, sync it only on demand.

[sheng: fix incorrect cr3 seen by Windows XP]
Signed-off-by: NSheng Yang <sheng@linux.intel.com>
Signed-off-by: NAvi Kivity <avi@redhat.com>

This allows us to keep cr3 in the VMCS, later on.
Signed-off-by: NAvi Kivity <avi@redhat.com>

If a pagetable contains a writeable large spte, all of its sptes will be
write protected, including non-leaf ones, leading to endless pagefaults.

Do not write protect pages above PT_PAGE_TABLE_LEVEL, as the spte fault
paths assume non-leaf sptes are writable.
Tested-by: NAlex Williamson <alex.williamson@redhat.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

'error' is byte sized, so use a byte register constraint.
Acked-by: NRandy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: NAvi Kivity <avi@redhat.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

Signed-off-by: NAvi Kivity <avi@redhat.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

When NX is enabled on the host but not on the guest, we use the entry/exit
msr load facility, which is slow.  Optimize it to use entry/exit efer load,
which is ~1200 cycles faster.
Signed-off-by: NAvi Kivity <avi@redhat.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

In case of a nested page fault or an intercepted #PF newer SVM
implementations provide a copy of the faulting instruction bytes
in the VMCB.
Use these bytes to feed the instruction emulator and avoid the costly
guest instruction fetch in this case.
Signed-off-by: NAndre Przywara <andre.przywara@amd.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

When the DecodeAssist feature is available, the linear address
is provided in the VMCB on INVLPG intercepts. Use it directly to
avoid any decoding and emulation.
This is only useful for shadow paging, though.
Signed-off-by: NAndre Przywara <andre.przywara@amd.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

Newer SVM implementations provide the GPR number in the VMCB, so
that the emulation path is no longer necesarry to handle debug
register access intercepts. Implement the handling in svm.c and
use it when the info is provided.
Signed-off-by: NAndre Przywara <andre.przywara@amd.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

Newer SVM implementations provide the GPR number in the VMCB, so
that the emulation path is no longer necesarry to handle CR
register access intercepts. Implement the handling in svm.c and
use it when the info is provided.
Signed-off-by: NAndre Przywara <andre.przywara@amd.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

the recent APM Vol.2 and the recent AMD CPUID specification describe
new CPUID features bits for SVM. Name them here for later usage.
Signed-off-by: NAndre Przywara <andre.przywara@amd.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

emulate_instruction had many callers, but only one used all
parameters. One parameter was unused, another one is now
hidden by a wrapper function (required for a future addition
anyway), so most callers use now a shorter parameter list.
Signed-off-by: NAndre Przywara <andre.przywara@amd.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

move the complete_insn_gp() helper function out of the VMX part
into the generic x86 part to make it usable by SVM.
Signed-off-by: NAndre Przywara <andre.przywara@amd.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

The handling of CR8 writes in KVM is currently somewhat cumbersome.
This patch makes it look like the other CR register handlers
and fixes a possible issue in VMX, where the RIP would be incremented
despite an injected #GP.
Signed-off-by: NAndre Przywara <andre.przywara@amd.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

In KVM_CREATE_IRQCHIP, kvm_io_bus_unregister_dev() is called without taking
slots_lock in the error handling path.
Signed-off-by: NTakuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp>
Signed-off-by: NAvi Kivity <avi@redhat.com>

userspace may check this extension in runtime.
Signed-off-by: NLai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: NAvi Kivity <avi@redhat.com>

Currently, we record '1' for count regardless of the real count.  Fix.
Signed-off-by: NAvi Kivity <avi@redhat.com>

If KVM sees a read-only host page, it will map it as read-only to prevent
breaking a COW.  However, if the page was part of a large guest page, KVM
incorrectly extends the write protection to the entire large page frame
instead of limiting it to the normal host page.

This results in the instantiation of a new shadow page with read-only access.

If this happens for a MOVS instruction that moves memory between two normal
pages, within a single large page frame, and mapped within the guest as a
large page, and if, in addition, the source operand is not writeable in the
host (perhaps due to KSM), then KVM will instantiate a read-only direct
shadow page, instantiate an spte for the source operand, then instantiate
a new read/write direct shadow page and instantiate an spte for the
destination operand.  Since these two sptes are in different shadow pages,
MOVS will never see them at the same time and the guest will not make
progress.

Fix by mapping the direct shadow page read/write, and only marking the
host page read-only.
Signed-off-by: NAvi Kivity <avi@redhat.com>

This patch implements the xsetbv intercept to the AMD part
of KVM. This makes AVX usable in a save way for the guest on
AVX capable AMD hardware.

The patch is tested by using AVX in the guest and host in
parallel and checking for data corruption. I also used the
KVM xsave unit-tests and they all pass.
Signed-off-by: NJoerg Roedel <joerg.roedel@amd.com>
Signed-off-by: NAvi Kivity <avi@redhat.com>

Large page information has two elements but one of them, write_count, alone
is accessed by a helper function.

This patch replaces this helper function with more generic one which returns
newly named kvm_lpage_info structure and use it to access the other element
rmap_pde.
Signed-off-by: NTakuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp>
Signed-off-by: NAvi Kivity <avi@redhat.com>

In certain use-cases, we want to allocate guests fixed time slices where idle
guest cycles leave the machine idling.  There are many approaches to achieve
this but the most direct is to simply avoid trapping the HLT instruction which
lets the guest directly execute the instruction putting the processor to sleep.

Introduce this as a module-level option for kvm-vmx.ko since if you do this
for one guest, you probably want to do it for all.
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>
Signed-off-by: NAvi Kivity <avi@redhat.com>

This patch adds the new flush-by-asid of upcoming AMD
processors to the KVM-AMD module.
Signed-off-by: NJoerg Roedel <joerg.roedel@amd.com>
Signed-off-by: NAvi Kivity <avi@redhat.com>

This patch replaces all calls to force_new_asid which are
intended to flush the guest-tlb by the more appropriate
function svm_flush_tlb. As a side-effect the force_new_asid
function is removed.
Signed-off-by: NJoerg Roedel <joerg.roedel@amd.com>
Signed-off-by: NAvi Kivity <avi@redhat.com>

This function is unused and there is svm_flush_tlb which
does the same. So this function can be removed.
Signed-off-by: NJoerg Roedel <joerg.roedel@amd.com>
Signed-off-by: NAvi Kivity <avi@redhat.com>

Retry #PF for softmmu only when the current vcpu has the same cr3 as the time
when #PF occurs
Signed-off-by: NXiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Signed-off-by: NAvi Kivity <avi@redhat.com>

Retry #PF is the speculative path, so don't set the accessed bit
Signed-off-by: NXiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Signed-off-by: NAvi Kivity <avi@redhat.com>

It's the speculative path if 'no_apf = 1' and we will specially handle this
speculative path in the later patch, so 'prefault' is better to fit the sense.
Signed-off-by: NXiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Signed-off-by: NAvi Kivity <avi@redhat.com>

This patch implements the clean-bit for all LBR related
state. This includes the debugctl, br_from, br_to,
last_excp_from, and last_excp_to msrs.
Signed-off-by: NJoerg Roedel <joerg.roedel@amd.com>
Signed-off-by: NAvi Kivity <avi@redhat.com>

This patch implements the clean-bit for the cr2 register in
the vmcb.
Signed-off-by: NJoerg Roedel <joerg.roedel@amd.com>
Signed-off-by: NAvi Kivity <avi@redhat.com>

This patch implements the clean-bit defined for the cs, ds,
ss, an es segemnts and the current cpl saved in the vmcb.
Signed-off-by: NJoerg Roedel <joerg.roedel@amd.com>
Signed-off-by: NAvi Kivity <avi@redhat.com>

This patch implements the clean-bit for the base and limit
of the gdt and idt in the vmcb.
Signed-off-by: NJoerg Roedel <joerg.roedel@amd.com>
Signed-off-by: NAvi Kivity <avi@redhat.com>

This patch implements the clean-bit for the dr6 and dr7
debug registers in the vmcb.
Signed-off-by: NJoerg Roedel <joerg.roedel@amd.com>
Signed-off-by: NAvi Kivity <avi@redhat.com>

This patch implements the CRx clean-bit for the vmcb. This
bit covers cr0, cr3, cr4, and efer.
Signed-off-by: NJoerg Roedel <joerg.roedel@amd.com>
Signed-off-by: NAvi Kivity <avi@redhat.com>