We switched to ABIv2 on Little Endian systems now which gets rid of the
dotted function names. Branch to the actual functions when we see such
a system.
Signed-off-by: Alexander Graf <agraf@suse.de>
Both kvmppc_hv_entry_trampoline and kvmppc_entry_trampoline are
assembly functions that are exported to modules and also require
a valid r2.
As such we need to use _GLOBAL_TOC so we provide a global entry
point that establishes the TOC (r2).
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Alexander Graf <agraf@suse.de>
To establish addressability quickly, ABIv2 requires the target
address of the function being called to be in r12.
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Alexander Graf <agraf@suse.de>
If we're running PR KVM in HV mode, we may get hypervisor doorbell interrupts.
Handle those the same way we treat normal doorbells.
Signed-off-by: Alexander Graf <agraf@suse.de>
When we're using PR KVM we must not allow the CPU to take interrupts
in virtual mode, as the SLB does not contain host kernel mappings
when running inside the guest context.
To make sure we get good performance for non-KVM tasks but still
properly functioning PR KVM, let's just disable AIL whenever a vcpu
is scheduled in.
This is fundamentally different from how we deal with AIL on pSeries
type machines where we disable AIL for the whole machine as soon as
a single KVM VM is up.
The reason for that is easy - on pSeries we do not have control over
per-cpu configuration of AIL. We also don't want to mess with CPU hotplug
races and AIL configuration, so setting it per CPU is easier and more
flexible.
This patch fixes running PR KVM on POWER8 bare metal for me.
Signed-off-by: Alexander Graf <agraf@suse.de>
Acked-by: Paul Mackerras <paulus@samba.org>
Writing to IC is not allowed in the privileged mode.
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Alexander Graf <agraf@suse.de>
virtual time base register is a per VM, per cpu register that needs
to be saved and restored on vm exit and entry. Writing to VTB is not
allowed in the privileged mode.
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
[agraf: fix compile error]
Signed-off-by: Alexander Graf <agraf@suse.de>
We use time base for PURR and SPURR emulation with PR KVM since we
are emulating a single threaded core. When using time base
we need to make sure that we don't accumulate time spent in the host
in PURR and SPURR value.
Also we don't need to emulate mtspr because both the registers are
hypervisor resource.
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Alexander Graf <agraf@suse.de>
Currently we forward MCEs to guest which have been recovered by guest.
And for unhandled errors we do not deliver the MCE to guest. It looks like
with no support of FWNMI in qemu, guest just panics whenever we deliver the
recovered MCEs to guest. Also, the existig code used to return to host for
unhandled errors which was casuing guest to hang with soft lockups inside
guest and makes it difficult to recover guest instance.
This patch now forwards all fatal MCEs to guest causing guest to crash/panic.
And, for recovered errors we just go back to normal functioning of guest
instead of returning to host. This fixes soft lockup issues in guest.
This patch also fixes an issue where guest MCE events were not logged to
host console.
Signed-off-by: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Pull powerpc updates from Ben Herrenschmidt:
"Here is the bulk of the powerpc changes for this merge window. It got
a bit delayed in part because I wasn't paying attention, and in part
because I discovered I had a core PCI change without a PCI maintainer
ack in it. Bjorn eventually agreed it was ok to merge it though we'll
probably improve it later and I didn't want to rebase to add his ack.
There is going to be a bit more next week, essentially fixes that I
still want to sort through and test.
The biggest item this time is the support to build the ppc64 LE kernel
with our new v2 ABI. We previously supported v2 userspace but the
kernel itself was a tougher nut to crack. This is now sorted mostly
thanks to Anton and Rusty.
We also have a fairly big series from Cedric that add support for
64-bit LE zImage boot wrapper. This was made harder by the fact that
traditionally our zImage wrapper was always 32-bit, but our new LE
toolchains don't really support 32-bit anymore (it's somewhat there
but not really "supported") so we didn't want to rely on it. This
meant more churn that just endian fixes.
This brings some more LE bits as well, such as the ability to run in
LE mode without a hypervisor (ie. under OPAL firmware) by doing the
right OPAL call to reinitialize the CPU to take HV interrupts in the
right mode and the usual pile of endian fixes.
There's another series from Gavin adding EEH improvements (one day we
*will* have a release with less than 20 EEH patches, I promise!).
Another highlight is the support for the "Split core" functionality on
P8 by Michael. This allows a P8 core to be split into "sub cores" of
4 threads which allows the subcores to run different guests under KVM
(the HW still doesn't support a partition per thread).
And then the usual misc bits and fixes ..."
[ Further delayed by gmail deciding that BenH is a dirty spammer.
Google knows. ]
* 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/benh/powerpc: (155 commits)
powerpc/powernv: Add missing include to LPC code
selftests/powerpc: Test the THP bug we fixed in the previous commit
powerpc/mm: Check paca psize is up to date for huge mappings
powerpc/powernv: Pass buffer size to OPAL validate flash call
powerpc/pseries: hcall functions are exported to modules, need _GLOBAL_TOC()
powerpc: Exported functions __clear_user and copy_page use r2 so need _GLOBAL_TOC()
powerpc/powernv: Set memory_block_size_bytes to 256MB
powerpc: Allow ppc_md platform hook to override memory_block_size_bytes
powerpc/powernv: Fix endian issues in memory error handling code
powerpc/eeh: Skip eeh sysfs when eeh is disabled
powerpc: 64bit sendfile is capped at 2GB
powerpc/powernv: Provide debugfs access to the LPC bus via OPAL
powerpc/serial: Use saner flags when creating legacy ports
powerpc: Add cpu family documentation
powerpc/xmon: Fix up xmon format strings
powerpc/powernv: Add calls to support little endian host
powerpc: Document sysfs DSCR interface
powerpc: Fix regression of per-CPU DSCR setting
powerpc: Split __SYSFS_SPRSETUP macro
arch: powerpc/fadump: Cleaning up inconsistent NULL checks
...
was a pretty active cycle for KVM. Changes include:
- a lot of s390 changes: optimizations, support for migration,
GDB support and more
- ARM changes are pretty small: support for the PSCI 0.2 hypercall
interface on both the guest and the host (the latter acked by Catalin)
- initial POWER8 and little-endian host support
- support for running u-boot on embedded POWER targets
- pretty large changes to MIPS too, completing the userspace interface
and improving the handling of virtualized timer hardware
- for x86, a larger set of changes is scheduled for 3.17. Still,
we have a few emulator bugfixes and support for running nested
fully-virtualized Xen guests (para-virtualized Xen guests have
always worked). And some optimizations too.
The only missing architecture here is ia64. It's not a coincidence
that support for KVM on ia64 is scheduled for removal in 3.17.
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Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm into next
Pull KVM updates from Paolo Bonzini:
"At over 200 commits, covering almost all supported architectures, this
was a pretty active cycle for KVM. Changes include:
- a lot of s390 changes: optimizations, support for migration, GDB
support and more
- ARM changes are pretty small: support for the PSCI 0.2 hypercall
interface on both the guest and the host (the latter acked by
Catalin)
- initial POWER8 and little-endian host support
- support for running u-boot on embedded POWER targets
- pretty large changes to MIPS too, completing the userspace
interface and improving the handling of virtualized timer hardware
- for x86, a larger set of changes is scheduled for 3.17. Still, we
have a few emulator bugfixes and support for running nested
fully-virtualized Xen guests (para-virtualized Xen guests have
always worked). And some optimizations too.
The only missing architecture here is ia64. It's not a coincidence
that support for KVM on ia64 is scheduled for removal in 3.17"
* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (203 commits)
KVM: add missing cleanup_srcu_struct
KVM: PPC: Book3S PR: Rework SLB switching code
KVM: PPC: Book3S PR: Use SLB entry 0
KVM: PPC: Book3S HV: Fix machine check delivery to guest
KVM: PPC: Book3S HV: Work around POWER8 performance monitor bugs
KVM: PPC: Book3S HV: Make sure we don't miss dirty pages
KVM: PPC: Book3S HV: Fix dirty map for hugepages
KVM: PPC: Book3S HV: Put huge-page HPTEs in rmap chain for base address
KVM: PPC: Book3S HV: Fix check for running inside guest in global_invalidates()
KVM: PPC: Book3S: Move KVM_REG_PPC_WORT to an unused register number
KVM: PPC: Book3S: Add ONE_REG register names that were missed
KVM: PPC: Add CAP to indicate hcall fixes
KVM: PPC: MPIC: Reset IRQ source private members
KVM: PPC: Graciously fail broken LE hypercalls
PPC: ePAPR: Fix hypercall on LE guest
KVM: PPC: BOOK3S: Remove open coded make_dsisr in alignment handler
KVM: PPC: BOOK3S: Always use the saved DAR value
PPC: KVM: Make NX bit available with magic page
KVM: PPC: Disable NX for old magic page using guests
KVM: PPC: BOOK3S: HV: Add mixed page-size support for guest
...
On LPAR guest systems Linux enables the shadow SLB to indicate to the
hypervisor a number of SLB entries that always have to be available.
Today we go through this shadow SLB and disable all ESID's valid bits.
However, pHyp doesn't like this approach very much and honors us with
fancy machine checks.
Fortunately the shadow SLB descriptor also has an entry that indicates
the number of valid entries following. During the lifetime of a guest
we can just swap that value to 0 and don't have to worry about the
SLB restoration magic.
While we're touching the code, let's also make it more readable (get
rid of rldicl), allow it to deal with a dynamic number of bolted
SLB entries and only do shadow SLB swizzling on LPAR systems.
Signed-off-by: Alexander Graf <agraf@suse.de>
We didn't make use of SLB entry 0 because ... of no good reason. SLB entry 0
will always be used by the Linux linear SLB entry, so the fact that slbia
does not invalidate it doesn't matter as we overwrite SLB 0 on exit anyway.
Just enable use of SLB entry 0 for our shadow SLB code.
Signed-off-by: Alexander Graf <agraf@suse.de>
The code that delivered a machine check to the guest after handling
it in real mode failed to load up r11 before calling kvmppc_msr_interrupt,
which needs the old MSR value in r11 so it can see the transactional
state there. This adds the missing load.
Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Alexander Graf <agraf@suse.de>
This adds workarounds for two hardware bugs in the POWER8 performance
monitor unit (PMU), both related to interrupt generation. The effect
of these bugs is that PMU interrupts can get lost, leading to tools
such as perf reporting fewer counts and samples than they should.
The first bug relates to the PMAO (perf. mon. alert occurred) bit in
MMCR0; setting it should cause an interrupt, but doesn't. The other
bug relates to the PMAE (perf. mon. alert enable) bit in MMCR0.
Setting PMAE when a counter is negative and counter negative
conditions are enabled to cause alerts should cause an alert, but
doesn't.
The workaround for the first bug is to create conditions where a
counter will overflow, whenever we are about to restore a MMCR0
value that has PMAO set (and PMAO_SYNC clear). The workaround for
the second bug is to freeze all counters using MMCR2 before reading
MMCR0.
Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Alexander Graf <agraf@suse.de>
Current, when testing whether a page is dirty (when constructing the
bitmap for the KVM_GET_DIRTY_LOG ioctl), we test the C (changed) bit
in the HPT entries mapping the page, and if it is 0, we consider the
page to be clean. However, the Power ISA doesn't require processors
to set the C bit to 1 immediately when writing to a page, and in fact
allows them to delay the writeback of the C bit until they receive a
TLB invalidation for the page. Thus it is possible that the page
could be dirty and we miss it.
Now, if there are vcpus running, this is not serious since the
collection of the dirty log is racy already - some vcpu could dirty
the page just after we check it. But if there are no vcpus running we
should return definitive results, in case we are in the final phase of
migrating the guest.
Also, if the permission bits in the HPTE don't allow writing, then we
know that no CPU can set C. If the HPTE was previously writable and
the page was modified, any C bit writeback would have been flushed out
by the tlbie that we did when changing the HPTE to read-only.
Otherwise we need to do a TLB invalidation even if the C bit is 0, and
then check the C bit.
Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Alexander Graf <agraf@suse.de>
The dirty map that we construct for the KVM_GET_DIRTY_LOG ioctl has
one bit per system page (4K/64K). Currently, we only set one bit in
the map for each HPT entry with the Change bit set, even if the HPT is
for a large page (e.g., 16MB). Userspace then considers only the
first system page dirty, though in fact the guest may have modified
anywhere in the large page.
To fix this, we make kvm_test_clear_dirty() return the actual number
of pages that are dirty (and rename it to kvm_test_clear_dirty_npages()
to emphasize that that's what it returns). In kvmppc_hv_get_dirty_log()
we then set that many bits in the dirty map.
Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Alexander Graf <agraf@suse.de>
Currently, when a huge page is faulted in for a guest, we select the
rmap chain to insert the HPTE into based on the guest physical address
that the guest tried to access. Since there is an rmap chain for each
system page, there are many rmap chains for the area covered by a huge
page (e.g. 256 for 16MB pages when PAGE_SIZE = 64kB), and the huge-page
HPTE could end up in any one of them.
For consistency, and to make the huge-page HPTEs easier to find, we now
put huge-page HPTEs in the rmap chain corresponding to the base address
of the huge page.
Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Alexander Graf <agraf@suse.de>
The global_invalidates() function contains a check that is intended
to tell whether we are currently executing in the context of a hypercall
issued by the guest. The reason is that the optimization of using a
local TLB invalidate instruction is only valid in that context. The
check was testing local_paca->kvm_hstate.kvm_vcore, which gets set
when entering the guest but no longer gets cleared when exiting the
guest. To fix this, we use the kvm_vcpu field instead, which does
get cleared when exiting the guest, by the kvmppc_release_hwthread()
calls inside kvmppc_run_core().
The effect of having the check wrong was that when kvmppc_do_h_remove()
got called from htab_write() on the destination machine during a
migration, it cleared the current cpu's bit in kvm->arch.need_tlb_flush.
This meant that when the guest started running in the destination VM,
it may miss out on doing a complete TLB flush, and therefore may end
up using stale TLB entries from a previous guest that used the same
LPID value.
This should make migration more reliable.
Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Alexander Graf <agraf@suse.de>
We worked around some nasty KVM magic page hcall breakages:
1) NX bit not honored, so ignore NX when we detect it
2) LE guests swizzle hypercall instruction
Without these fixes in place, there's no way it would make sense to expose kvm
hypercalls to a guest. Chances are immensely high it would trip over and break.
So add a new CAP that gives user space a hint that we have workarounds for the
bugs above in place. It can use those as hint to disable PV hypercalls when
the guest CPU is anything POWER7 or higher and the host does not have fixes
in place.
Signed-off-by: Alexander Graf <agraf@suse.de>
When we reset the in-kernel MPIC controller, we forget to reset some hidden
state such as destmask and output. This state is usually set when the guest
writes to the IDR register for a specific IRQ line.
To make sure we stay in sync and don't forget hidden state, treat reset of
the IDR register as a simple write of the IDR register. That automatically
updates all the hidden state as well.
Reported-by: Paul Janzen <pcj@pauljanzen.org>
Signed-off-by: Alexander Graf <agraf@suse.de>
There are LE Linux guests out there that don't handle hypercalls correctly.
Instead of interpreting the instruction stream from device tree as big endian
they assume it's a little endian instruction stream and fail.
When we see an illegal instruction from such a byte reversed instruction stream,
bail out graciously and just declare every hcall as error.
Signed-off-by: Alexander Graf <agraf@suse.de>
Use make_dsisr instead of open coding it. This also have
the added benefit of handling alignment interrupt on additional
instructions.
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Alexander Graf <agraf@suse.de>
Although it's optional, IBM POWER cpus always had DAR value set on
alignment interrupt. So don't try to compute these values.
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Alexander Graf <agraf@suse.de>
Old guests try to use the magic page, but map their trampoline code inside
of an NX region.
Since we can't fix those old kernels, try to detect whether the guest is sane
or not. If not, just disable NX functionality in KVM so that old guests at
least work at all. For newer guests, add a bit that we can set to keep NX
functionality available.
Signed-off-by: Alexander Graf <agraf@suse.de>
On recent IBM Power CPUs, while the hashed page table is looked up using
the page size from the segmentation hardware (i.e. the SLB), it is
possible to have the HPT entry indicate a larger page size. Thus for
example it is possible to put a 16MB page in a 64kB segment, but since
the hash lookup is done using a 64kB page size, it may be necessary to
put multiple entries in the HPT for a single 16MB page. This
capability is called mixed page-size segment (MPSS). With MPSS,
there are two relevant page sizes: the base page size, which is the
size used in searching the HPT, and the actual page size, which is the
size indicated in the HPT entry. [ Note that the actual page size is
always >= base page size ].
We use "ibm,segment-page-sizes" device tree node to advertise
the MPSS support to PAPR guest. The penc encoding indicates whether
we support a specific combination of base page size and actual
page size in the same segment. We also use the penc value in the
LP encoding of HPTE entry.
This patch exposes MPSS support to KVM guest by advertising the
feature via "ibm,segment-page-sizes". It also adds the necessary changes
to decode the base page size and the actual page size correctly from the
HPTE entry.
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Alexander Graf <agraf@suse.de>
Today when KVM tries to reserve memory for the hash page table it
allocates from the normal page allocator first. If that fails it
falls back to CMA's reserved region. One of the side effects of
this is that we could end up exhausting the page allocator and
get linux into OOM conditions while we still have plenty of space
available in CMA.
This patch addresses this issue by first trying hash page table
allocation from CMA's reserved region before falling back to the normal
page allocator. So if we run out of memory, we really are out of memory.
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Alexander Graf <agraf@suse.de>
POWER8 introduces transactional memory which brings along a number of new
registers and MSR bits.
Implementing all of those is a pretty big headache, so for now let's at least
emulate enough to make Linux's context switching code happy.
Signed-off-by: Alexander Graf <agraf@suse.de>
POWER8 introduces a new facility called the "Event Based Branch" facility.
It contains of a few registers that indicate where a guest should branch to
when a defined event occurs and it's in PR mode.
We don't want to really enable EBB as it will create a big mess with !PR guest
mode while hardware is in PR and we don't really emulate the PMU anyway.
So instead, let's just leave it at emulation of all its registers.
Signed-off-by: Alexander Graf <agraf@suse.de>
POWER8 implements a new register called TAR. This register has to be
enabled in FSCR and then from KVM's point of view is mere storage.
This patch enables the guest to use TAR.
Signed-off-by: Alexander Graf <agraf@suse.de>
POWER8 introduced a new interrupt type called "Facility unavailable interrupt"
which contains its status message in a new register called FSCR.
Handle these exits and try to emulate instructions for unhandled facilities.
Follow-on patches enable KVM to expose specific facilities into the guest.
Signed-off-by: Alexander Graf <agraf@suse.de>
In parallel to the Processor ID Register (PIR) threaded POWER8 also adds a
Thread ID Register (TIR). Since PR KVM doesn't emulate more than one thread
per core, we can just always expose 0 here.
Signed-off-by: Alexander Graf <agraf@suse.de>
When we expose a POWER8 CPU into the guest, it will start accessing PMU SPRs
that we don't emulate. Just ignore accesses to them.
Signed-off-by: Alexander Graf <agraf@suse.de>
With the previous patches applied, we can now successfully use PR KVM on
little endian hosts which means we can now allow users to select it.
However, HV KVM still needs some work, so let's keep the kconfig conflict
on that one.
Signed-off-by: Alexander Graf <agraf@suse.de>
When the host CPU we're running on doesn't support dcbz32 itself, but the
guest wants to have dcbz only clear 32 bytes of data, we loop through every
executable mapped page to search for dcbz instructions and patch them with
a special privileged instruction that we emulate as dcbz32.
The only guests that want to see dcbz act as 32byte are book3s_32 guests, so
we don't have to worry about little endian instruction ordering. So let's
just always search for big endian dcbz instructions, also when we're on a
little endian host.
Signed-off-by: Alexander Graf <agraf@suse.de>
The shared (magic) page is a data structure that contains often used
supervisor privileged SPRs accessible via memory to the user to reduce
the number of exits we have to take to read/write them.
When we actually share this structure with the guest we have to maintain
it in guest endianness, because some of the patch tricks only work with
native endian load/store operations.
Since we only share the structure with either host or guest in little
endian on book3s_64 pr mode, we don't have to worry about booke or book3s hv.
For booke, the shared struct stays big endian. For book3s_64 hv we maintain
the struct in host native endian, since it never gets shared with the guest.
For book3s_64 pr we introduce a variable that tells us which endianness the
shared struct is in and route every access to it through helper inline
functions that evaluate this variable.
Signed-off-by: Alexander Graf <agraf@suse.de>
We expose a blob of hypercall instructions to user space that it gives to
the guest via device tree again. That blob should contain a stream of
instructions necessary to do a hypercall in big endian, as it just gets
passed into the guest and old guests use them straight away.
Signed-off-by: Alexander Graf <agraf@suse.de>
When the guest does an RTAS hypercall it keeps all RTAS variables inside a
big endian data structure.
To make sure we don't have to bother about endianness inside the actual RTAS
handlers, let's just convert the whole structure to host endian before we
call our RTAS handlers and back to big endian when we return to the guest.
Signed-off-by: Alexander Graf <agraf@suse.de>
The HTAB on PPC is always in big endian. When we access it via hypercalls
on behalf of the guest and we're running on a little endian host, we need
to make sure we swap the bits accordingly.
Signed-off-by: Alexander Graf <agraf@suse.de>
The default MSR when user space does not define anything should be identical
on little and big endian hosts, so remove MSR_LE from it.
Signed-off-by: Alexander Graf <agraf@suse.de>
The "shadow SLB" in the PACA is shared with the hypervisor, so it has to
be big endian. We access the shadow SLB during world switch, so let's make
sure we access it in big endian even when we're on a little endian host.
Signed-off-by: Alexander Graf <agraf@suse.de>
The HTAB is always big endian. We access the guest's HTAB using
copy_from/to_user, but don't yet take care of the fact that we might
be running on an LE host.
Wrap all accesses to the guest HTAB with big endian accessors.
Signed-off-by: Alexander Graf <agraf@suse.de>
The HTAB is always big endian. We access the guest's HTAB using
copy_from/to_user, but don't yet take care of the fact that we might
be running on an LE host.
Wrap all accesses to the guest HTAB with big endian accessors.
Signed-off-by: Alexander Graf <agraf@suse.de>
Commit 9308ab8e2d made C/R HTAB updates go byte-wise into the target HTAB.
However, it didn't update the guest's copy of the HTAB, but instead the
host local copy of it.
Write to the guest's HTAB instead.
Signed-off-by: Alexander Graf <agraf@suse.de>
CC: Paul Mackerras <paulus@samba.org>
Acked-by: Paul Mackerras <paulus@samba.org>
This patch make sure we inherit the LE bit correctly in different case
so that we can run Little Endian distro in PR mode
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Alexander Graf <agraf@suse.de>
The dcbtls instruction is able to lock data inside the L1 cache.
We don't want to give the guest actual access to hardware cache locks,
as that could influence other VMs on the same system. But we can tell
the guest that its locking attempt failed.
By implementing the instruction we at least don't give the guest a
program exception which it definitely does not expect.
Signed-off-by: Alexander Graf <agraf@suse.de>
The L1 instruction cache control register contains bits that indicate
that we're still handling a request. Mask those out when we set the SPR
so that a read doesn't assume we're still doing something.
Signed-off-by: Alexander Graf <agraf@suse.de>
Since commit "efcac65 powerpc: Per process DSCR + some fixes (try#4)"
it is no longer possible to set the DSCR on a per-CPU basis.
The old behaviour was to minipulate the DSCR SPR directly but this is no
longer sufficient: the value is quickly overwritten by context switching.
This patch stores the per-CPU DSCR value in a kernel variable rather than
directly in the SPR and it is used whenever a process has not set the DSCR
itself. The sysfs interface (/sys/devices/system/cpu/cpuN/dscr) is unchanged.
Writes to the old global default (/sys/devices/system/cpu/dscr_default)
now set all of the per-CPU values and reads return the last written value.
The new per-CPU default is added to the paca_struct and is used everywhere
outside of sysfs.c instead of the old global default.
Signed-off-by: Sam Bobroff <sam.bobroff@au1.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To support split core on POWER8 we need to modify various parts of the
KVM code to use threads_per_subcore instead of threads_per_core. On
systems that do not support split core threads_per_subcore ==
threads_per_core and these changes are a nop.
We use threads_per_subcore as the value reported by KVM_CAP_PPC_SMT.
This communicates to userspace that guests can only be created with
a value of threads_per_core that is less than or equal to the current
threads_per_subcore. This ensures that guests can only be created with a
thread configuration that we are able to run given the current split
core mode.
Although threads_per_subcore can change during the life of the system,
the commit that enables that will ensure that threads_per_subcore does
not change during the life of a KVM VM.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Michael Neuling <mikey@neuling.org>
Acked-by: Alexander Graf <agraf@suse.de>
Acked-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
