KVM: Remove redundant reading of rax on OUT instructions
kvm_emulate_pio() and complete_pio() both read out the
RAX register value and copy it to a place into which
the value read out from the port will be copied later.
This patch removes this redundancy.
/*** snippet from arch/x86/kvm/x86.c ***/
int complete_pio(struct kvm_vcpu *vcpu)
{
...
if (!io->string) {
if (io->in) {
val = kvm_register_read(vcpu, VCPU_REGS_RAX);
memcpy(&val, vcpu->arch.pio_data, io->size);
kvm_register_write(vcpu, VCPU_REGS_RAX, val);
}
...
Signed-off-by: Takuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp> Signed-off-by: Avi Kivity <avi@redhat.com>
Rik van Riel [Wed, 3 Feb 2010 21:11:03 +0000 (16:11 -0500)]
KVM: VMX: emulate accessed bit for EPT
Currently KVM pretends that pages with EPT mappings never got
accessed. This has some side effects in the VM, like swapping
out actively used guest pages and needlessly breaking up actively
used hugepages.
We can avoid those very costly side effects by emulating the
accessed bit for EPT PTEs, which should only be slightly costly
because pages pass through page_referenced infrequently.
TLB flushing is taken care of by kvm_mmu_notifier_clear_flush_young().
This seems to help prevent KVM guests from being swapped out when
they should not on my system.
Signed-off-by: Rik van Riel <riel@redhat.com> Signed-off-by: Avi Kivity <avi@redhat.com>
Joerg Roedel [Thu, 28 Jan 2010 11:37:56 +0000 (12:37 +0100)]
KVM: Introduce kvm_host_page_size
This patch introduces a generic function to find out the
host page size for a given gfn. This function is needed by
the kvm iommu code. This patch also simplifies the x86
host_mapping_level function.
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com> Signed-off-by: Avi Kivity <avi@redhat.com>
This patch fixes kvm_fix_hypercall() to propagate X86EMUL_*
info generated by emulator_write_emulated() to its callers:
suggested by Marcelo.
The effect of this is x86_emulate_insn() will begin to handle
the page faults which occur in emulator_write_emulated():
this should be OK because emulator_write_emulated_onepage()
always injects page fault when emulator_write_emulated()
returns X86EMUL_PROPAGATE_FAULT.
KVM: fix load_guest_segment_descriptor() to return X86EMUL_*
This patch fixes load_guest_segment_descriptor() to return
X86EMUL_PROPAGATE_FAULT when it tries to access the descriptor
table beyond the limit of it: suggested by Marcelo.
I have checked current callers of this helper function,
- kvm_load_segment_descriptor()
- kvm_task_switch()
and confirmed that this patch will change nothing in the
upper layers if we do not change the handling of this
return value from load_guest_segment_descriptor().
Next step: Although fixing the kvm_task_switch() to handle the
propagated faults properly seems difficult, and maybe not worth
it because TSS is not used commonly these days, we can fix
kvm_load_segment_descriptor(). By doing so, the injected #GP
becomes possible to be handled by the guest. The only problem
for this is how to differentiate this fault from the page faults
generated by kvm_read_guest_virt(). We may have to split this
function to achive this goal.
Avi Kivity [Sun, 24 Jan 2010 14:26:40 +0000 (16:26 +0200)]
KVM: VMX: Pass cr0.mp through to the guest when the fpu is active
When cr0.mp is clear, the guest doesn't expect a #NM in response to
a WAIT instruction. Because we always keep cr0.mp set, it will get
a #NM, and potentially be confused.
Fix by keeping cr0.mp set only when the fpu is inactive, and passing
it through when inactive.
Reported-by: Lorenzo Martignoni <martignlo@gmail.com> Analyzed-by: Gleb Natapov <gleb@redhat.com> Signed-off-by: Avi Kivity <avi@redhat.com> Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Wei Yongjun [Fri, 22 Jan 2010 08:55:05 +0000 (16:55 +0800)]
KVM: MMU: Remove some useless code from alloc_mmu_pages()
If we fail to alloc page for vcpu->arch.mmu.pae_root, call to
free_mmu_pages() is unnecessary, which just do free the page
malloc for vcpu->arch.mmu.pae_root.
Avi Kivity [Thu, 21 Jan 2010 13:31:51 +0000 (15:31 +0200)]
KVM: Optimize kvm_read_cr[04]_bits()
'mask' is always a constant, so we can check whether it includes a bit that
might be owned by the guest very cheaply, and avoid the decache call. Saves
a few hundred bytes of module text.
Signed-off-by: Avi Kivity <avi@redhat.com> Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Gleb Natapov [Thu, 21 Jan 2010 13:28:46 +0000 (15:28 +0200)]
KVM: x86: fix checking of cr0 validity
Move to/from Control Registers chapter of Intel SDM says. "Reserved bits
in CR0 remain clear after any load of those registers; attempts to set
them have no impact". Control Register chapter says "Bits 63:32 of CR0 are
reserved and must be written with zeros. Writing a nonzero value to any
of the upper 32 bits results in a general-protection exception, #GP(0)."
The commit 0953ca73 "KVM: Simplify coalesced mmio initialization"
allocate kvm_coalesced_mmio_ring in the kvm_coalesced_mmio_init(), but
didn't discard the original allocation...
Signed-off-by: Sheng Yang <sheng@linux.intel.com> Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Jan Kiszka [Wed, 20 Jan 2010 17:20:20 +0000 (18:20 +0100)]
KVM: SVM: Clean up and enhance mov dr emulation
Enhance mov dr instruction emulation used by SVM so that it properly
handles dr4/5: alias to dr6/7 if cr4.de is cleared. Otherwise return
EMULATE_FAIL which will let our only possible caller in that scenario,
ud_interception, re-inject UD.
We do not need to inject faults, SVM does this for us (exceptions take
precedence over instruction interceptions). For the same reason, the
value overflow checks can be removed.
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com> Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Jan Kiszka [Wed, 20 Jan 2010 17:20:20 +0000 (18:20 +0100)]
KVM: VMX: Fix exceptions of mov to dr
Injecting GP without an error code is a bad idea (causes unhandled guest
exits). Moreover, we must not skip the instruction if we injected an
exception.
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com> Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Takuya Yoshikawa [Wed, 20 Jan 2010 07:47:21 +0000 (16:47 +0900)]
KVM: x86: Use macros for x86_emulate_ops to avoid future mistakes
The return values from x86_emulate_ops are defined
in kvm_emulate.h as macros X86EMUL_*.
But in emulate.c, we are comparing the return values
from these ops with 0 to check if they're X86EMUL_CONTINUE
or not: X86EMUL_CONTINUE is defined as 0 now.
To avoid possible mistakes in the future, this patch
substitutes "X86EMUL_CONTINUE" for "0" that are being
compared with the return values from x86_emulate_ops.
We think that there are more places we should use these
macros, but the meanings of rc values in x86_emulate_insn()
were not so clear at a glance. If we use proper macros in
this function, we would be able to follow the flow of each
emulation more easily and, maybe, more securely.
Sheng Yang [Tue, 19 Jan 2010 09:43:21 +0000 (17:43 +0800)]
KVM: VMX: Remove emulation failure report
As Avi noted:
>There are two problems with the kernel failure report. First, it
>doesn't report enough data - registers, surrounding instructions, etc.
>that are needed to explain what is going on. Second, it can flood
>dmesg, which is a pretty bad thing to do.
So we remove the emulation failure report in handle_invalid_guest_state(),
and would inspected the guest using userspace tool in the future.
Signed-off-by: Sheng Yang <sheng@linux.intel.com> Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Alexander Graf [Fri, 15 Jan 2010 13:49:14 +0000 (14:49 +0100)]
KVM: PPC: Move Shadow MSR calculation to function
We keep a copy of the MSR around that we use when we go into the guest context.
That copy is basically the normal process MSR flags OR some allowed guest
specified MSR flags. We also AND the external providers into this, so we get
traps on FPU usage when we haven't activated it on the host yet.
Currently this calculation is part of the set_msr function that we use whenever
we set the guest MSR value. With the external providers, we also have the case
that we don't modify the guest's MSR, but only want to update the shadow MSR.
So let's move the shadow MSR parts to a separate function that we then use
whenever we only need to update it. That way we don't accidently kvm_vcpu_block
within a preempt notifier context.
Signed-off-by: Alexander Graf <agraf@suse.de> Signed-off-by: Avi Kivity <avi@redhat.com>
Alexander Graf [Fri, 15 Jan 2010 13:49:13 +0000 (14:49 +0100)]
KVM: PPC: Keep SRR1 flags around in shadow_msr
SRR1 stores more information that just the MSR value. It also stores
valuable information about the type of interrupt we received, for
example whether the storage interrupt we just got was because of a
missing htab entry or not.
We use that information to speed up the exit path.
Now if we get preempted before we can interpret the shadow_msr values,
we get into vcpu_put which then calls the MSR handler, which then sets
all the SRR1 information bits in shadow_msr to 0. Great.
So let's preserve the SRR1 specific bits in shadow_msr whenever we set
the MSR. They don't hurt.
Signed-off-by: Alexander Graf <agraf@suse.de> Signed-off-by: Avi Kivity <avi@redhat.com>
Alexander Graf [Fri, 15 Jan 2010 13:49:12 +0000 (14:49 +0100)]
KVM: PPC: Fix initial GPR settings
Commit 7d01b4c3ed2bb33ceaf2d270cb4831a67a76b51b introduced PACA backed vcpu
values. With this patch, when a userspace app was setting GPRs before it was
actually first loaded, the set values get discarded.
This is because vcpu_load loads them from the vcpu backing store that we use
whenever we're not owning the PACA.
That behavior is not really a major problem, because we don't need it for
qemu. Other users (like kvmctl) do have problems with it though, so let's
better do it right.
Signed-off-by: Alexander Graf <agraf@suse.de> Signed-off-by: Avi Kivity <avi@redhat.com>
Alexander Graf [Fri, 15 Jan 2010 13:49:11 +0000 (14:49 +0100)]
KVM: PPC: Add support for FPU/Altivec/VSX
When our guest starts using either the FPU, Altivec or VSX we need to make
sure Linux knows about it and sneak into its process switching code
accordingly.
This patch makes accesses to the above parts of the system work inside the
VM.
Signed-off-by: Alexander Graf <agraf@suse.de> Signed-off-by: Avi Kivity <avi@redhat.com>
Alexander Graf [Fri, 15 Jan 2010 13:49:10 +0000 (14:49 +0100)]
KVM: PPC: Add helper functions to call real mode loaders
Linux contains quite some bits of code to load FPU, Altivec and VSX lazily for
a task. It calls those bits in real mode, coming from an interrupt handler.
For KVM we better reuse those, so let's wrap a bit of trampoline magic around
them and then we can call them from normal module code.
Signed-off-by: Alexander Graf <agraf@suse.de> Signed-off-by: Avi Kivity <avi@redhat.com>
Avi Kivity [Wed, 6 Jan 2010 08:55:27 +0000 (10:55 +0200)]
KVM: SVM: Selective cr0 intercept
If two conditions apply:
- no bits outside TS and EM differ between the host and guest cr0
- the fpu is active
then we can activate the selective cr0 write intercept and drop the
unconditional cr0 read and write intercept, and allow the guest to run
with the host fpu state. This reduces cr0 exits due to guest fpu management
while the guest fpu is loaded.
Acked-by: Joerg Roedel <joerg.roedel@amd.com> Signed-off-by: Avi Kivity <avi@redhat.com>
Avi Kivity [Thu, 7 Jan 2010 11:16:08 +0000 (13:16 +0200)]
KVM: SVM: Initialize fpu_active in init_vmcb()
init_vmcb() sets up the intercepts as if the fpu is active, so initialize it
there. This avoids an INIT from setting up intercepts inconsistent with
fpu_active.
Acked-by: Joerg Roedel <joerg.roedel@amd.com> Signed-off-by: Avi Kivity <avi@redhat.com>
Avi Kivity [Wed, 6 Jan 2010 11:13:01 +0000 (13:13 +0200)]
KVM: SVM: Fix SVM_CR0_SELECTIVE_MASK
Instead of selecting TS and MP as the comments say, the macro included TS and
PE. Luckily the macro is unused now, but fix in order to save a few hours of
debugging from anyone who attempts to use it.
Acked-by: Joerg Roedel <joerg.roedel@amd.com> Signed-off-by: Avi Kivity <avi@redhat.com>
Avi Kivity [Wed, 30 Dec 2009 16:07:40 +0000 (18:07 +0200)]
KVM: VMX: Give the guest ownership of cr0.ts when the fpu is active
If the guest fpu is loaded, there is nothing interesing about cr0.ts; let
the guest play with it as it will. This makes context switches between fpu
intensive guest processes faster, as we won't trap the clts and cr0 write
instructions.
Avi Kivity [Wed, 30 Dec 2009 10:40:26 +0000 (12:40 +0200)]
KVM: Lazify fpu activation and deactivation
Defer fpu deactivation as much as possible - if the guest fpu is loaded, keep
it loaded until the next heavyweight exit (where we are forced to unload it).
This reduces unnecessary exits.
We also defer fpu activation on clts; while clts signals the intent to use the
fpu, we can't be sure the guest will actually use it.
Alexander Graf [Sun, 10 Jan 2010 02:27:47 +0000 (03:27 +0100)]
KVM: PPC: Make large pages work
An SLB entry contains two pieces of information related to size:
1) PTE size
2) SLB size
The L bit defines the PTE be "large" (usually means 16MB),
SLB_VSID_B_1T defines that the SLB should span 1 GB instead of the
default 256MB.
Apparently I messed things up and just put those two in one box,
shaked it heavily and came up with the current code which handles
large pages incorrectly, because it also treats large page SLB entries
as "1TB" segment entries.
This patch splits those two features apart, making Linux guests boot
even when they have > 256MB.
Signed-off-by: Alexander Graf <agraf@suse.de> Signed-off-by: Avi Kivity <avi@redhat.com>
Alexander Graf [Sun, 10 Jan 2010 02:27:32 +0000 (03:27 +0100)]
KVM: PPC: Pass through program interrupts
When we get a program interrupt in guest kernel mode, we try to emulate the
instruction.
If that doesn't fail, we report to the user and try again - at the exact same
instruction pointer. So if the guest kernel really does trigger an invalid
instruction, we loop forever.
So let's better go and forward program exceptions to the guest when we don't
know the instruction we're supposed to emulate.
Signed-off-by: Alexander Graf <agraf@suse.de> Signed-off-by: Avi Kivity <avi@redhat.com>
Alexander Graf [Fri, 8 Jan 2010 01:58:09 +0000 (02:58 +0100)]
KVM: PPC: Pass program interrupt flags to the guest
When we need to reinject a program interrupt into the guest, we also need to
reinject the corresponding flags into the guest.
Signed-off-by: Alexander Graf <agraf@suse.de> Reported-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Signed-off-by: Avi Kivity <avi@redhat.com>
Alexander Graf [Fri, 8 Jan 2010 01:58:08 +0000 (02:58 +0100)]
KVM: PPC: Fix HID5 setting code
The code to unset HID5.dcbz32 is broken.
This patch makes it do the right rotate magic.
Signed-off-by: Alexander Graf <agraf@suse.de> Reported-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Signed-off-by: Avi Kivity <avi@redhat.com>
Alexander Graf [Fri, 8 Jan 2010 01:58:05 +0000 (02:58 +0100)]
KVM: PPC: Get rid of unnecessary RFI
Using an RFI in IR=1 is dangerous. We need to set two SRRs and then do an RFI
without getting interrupted at all, because every interrupt could potentially
overwrite the SRR values.
Fortunately, we don't need to RFI in at least this particular case of the code,
so we can just replace it with an mtmsr and b.
Signed-off-by: Alexander Graf <agraf@suse.de> Signed-off-by: Avi Kivity <avi@redhat.com>
Alexander Graf [Fri, 8 Jan 2010 01:58:04 +0000 (02:58 +0100)]
KVM: PPC: Implement 'skip instruction' mode
To fetch the last instruction we were interrupted on, we enable DR in early
exit code, where we are still in a very transitional phase between guest
and host state.
Most of the time this seemed to work, but another CPU can easily flush our
TLB and HTAB which makes us go in the Linux page fault handler which totally
breaks because we still use the guest's SLB entries.
To work around that, let's introduce a second KVM guest mode that defines
that whenever we get a trap, we don't call the Linux handler or go into
the KVM exit code, but just jump over the faulting instruction.
That way a potentially bad lwz doesn't trigger any faults and we can later
on interpret the invalid instruction we fetched as "fetch didn't work".
Signed-off-by: Alexander Graf <agraf@suse.de> Signed-off-by: Avi Kivity <avi@redhat.com>
Alexander Graf [Fri, 8 Jan 2010 01:58:03 +0000 (02:58 +0100)]
KVM: PPC: Use PACA backed shadow vcpu
We're being horribly racy right now. All the entry and exit code hijacks
random fields from the PACA that could easily be used by different code in
case we get interrupted, for example by a #MC or even page fault.
After discussing this with Ben, we figured it's best to reserve some more
space in the PACA and just shove off some vcpu state to there.
That way we can drastically improve the readability of the code, make it
less racy and less complex.
Signed-off-by: Alexander Graf <agraf@suse.de> Signed-off-by: Avi Kivity <avi@redhat.com>
Alexander Graf [Fri, 8 Jan 2010 01:58:01 +0000 (02:58 +0100)]
KVM: PPC: Use accessor functions for GPR access
All code in PPC KVM currently accesses gprs in the vcpu struct directly.
While there's nothing wrong with that wrt the current way gprs are stored
and loaded, it doesn't suffice for the PACA acceleration that will follow
in this patchset.
So let's just create little wrapper inline functions that we call whenever
a GPR needs to be read from or written to. The compiled code shouldn't really
change at all for now.
Signed-off-by: Alexander Graf <agraf@suse.de> Signed-off-by: Avi Kivity <avi@redhat.com>
Alexander Graf [Mon, 4 Jan 2010 21:19:25 +0000 (22:19 +0100)]
KVM: PPC: Enable lightweight exits again
The PowerPC C ABI defines that registers r14-r31 need to be preserved across
function calls. Since our exit handler is written in C, we can make use of that
and don't need to reload r14-r31 on every entry/exit cycle.
This technique is also used in the BookE code and is called "lightweight exits"
there. To follow the tradition, it's called the same in Book3S.
So far this optimization was disabled though, as the code didn't do what it was
expected to do, but failed to work.
This patch fixes and enables lightweight exits again.
Signed-off-by: Alexander Graf <agraf@suse.de> Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Avi Kivity [Mon, 28 Dec 2009 12:08:30 +0000 (14:08 +0200)]
KVM: avoid taking ioapic mutex for non-ioapic EOIs
When the guest acknowledges an interrupt, it sends an EOI message to the local
apic, which broadcasts it to the ioapic. To handle the EOI, we need to take
the ioapic mutex.
On large guests, this causes a lot of contention on this mutex. Since large
guests usually don't route interrupts via the ioapic (they use msi instead),
this is completely unnecessary.
Avoid taking the mutex by introducing a handled_vectors bitmap. Before taking
the mutex, check if the ioapic was actually responsible for the acked vector.
If not, we can return early.
Signed-off-by: Avi Kivity <avi@redhat.com> Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Avi Kivity [Sun, 27 Dec 2009 15:00:46 +0000 (17:00 +0200)]
KVM: Bump maximum vcpu count to 64
With slots_lock converted to rcu, the entire kvm hotpath on modern processors
(with npt or ept) now scales beautifully. Increase the maximum vcpu count to
64 to reflect this.
Signed-off-by: Avi Kivity <avi@redhat.com> Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Marcelo Tosatti [Wed, 23 Dec 2009 16:35:21 +0000 (14:35 -0200)]
KVM: introduce kvm->srcu and convert kvm_set_memory_region to SRCU update
Use two steps for memslot deletion: mark the slot invalid (which stops
instantiation of new shadow pages for that slot, but allows destruction),
then instantiate the new empty slot.
Alexander Graf [Mon, 21 Dec 2009 19:21:24 +0000 (20:21 +0100)]
KVM: powerpc: Improve DEC handling
We treated the DEC interrupt like an edge based one. This is not true for
Book3s. The DEC keeps firing until mtdec is issued again and thus clears
the interrupt line.
So let's implement this logic in KVM too. This patch moves the line clearing
from the firing of the interrupt to the mtdec emulation.
This makes PPC64 guests work without AGGRESSIVE_DEC defined.
Signed-off-by: Alexander Graf <agraf@suse.de> Acked-by: Acked-by: Hollis Blanchard <hollis@penguinppc.org> Signed-off-by: Avi Kivity <avi@redhat.com>
projects / mv-sheeva.git / log