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: NAlexander Graf <agraf@suse.de>

Signed-off-by: NAneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
[agraf: squash in compile fix]
Signed-off-by: NAlexander Graf <agraf@suse.de>

This patch add a new callback kvmppc_ops. This will help us in enabling
both HV and PR KVM together in the same kernel. The actual change to
enable them together is done in the later patch in the series.
Signed-off-by: NAneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
[agraf: squash in booke changes]
Signed-off-by: NAlexander Graf <agraf@suse.de>

Currently PR-style KVM keeps the volatile guest register values
(R0 - R13, CR, LR, CTR, XER, PC) in a shadow_vcpu struct rather than
the main kvm_vcpu struct.  For 64-bit, the shadow_vcpu exists in two
places, a kmalloc'd struct and in the PACA, and it gets copied back
and forth in kvmppc_core_vcpu_load/put(), because the real-mode code
can't rely on being able to access the kmalloc'd struct.

This changes the code to copy the volatile values into the shadow_vcpu
as one of the last things done before entering the guest.  Similarly
the values are copied back out of the shadow_vcpu to the kvm_vcpu
immediately after exiting the guest.  We arrange for interrupts to be
still disabled at this point so that we can't get preempted on 64-bit
and end up copying values from the wrong PACA.

This means that the accessor functions in kvm_book3s.h for these
registers are greatly simplified, and are same between PR and HV KVM.
In places where accesses to shadow_vcpu fields are now replaced by
accesses to the kvm_vcpu, we can also remove the svcpu_get/put pairs.
Finally, on 64-bit, we don't need the kmalloc'd struct at all any more.

With this, the time to read the PVR one million times in a loop went
from 567.7ms to 575.5ms (averages of 6 values), an increase of about
1.4% for this worse-case test for guest entries and exits.  The
standard deviation of the measurements is about 11ms, so the
difference is only marginally significant statistically.
Signed-off-by: NPaul Mackerras <paulus@samba.org>
Signed-off-by: NAlexander Graf <agraf@suse.de>

We don't emulate breakpoints yet, so just ignore reads and writes
to / from DABR.

This fixes booting of more recent Linux guest kernels for me.
Reported-by: NNello Martuscielli <ppc.addon@gmail.com>
Tested-by: NNello Martuscielli <ppc.addon@gmail.com>
Signed-off-by: NAlexander Graf <agraf@suse.de>

Currently the instruction emulator code returns EMULATE_EXIT_USER
and common code initializes the "run->exit_reason = .." and
"vcpu->arch.hcall_needed = .." with one fixed reason.
But there can be different reasons when emulator need to exit
to user space. To support that the "run->exit_reason = .."
and "vcpu->arch.hcall_needed = .." initialization is moved a
level up to emulator.
Signed-off-by: NBharat Bhushan <bharat.bhushan@freescale.com>
Signed-off-by: NAlexander Graf <agraf@suse.de>

Instruction emulation return EMULATE_DO_PAPR when it requires
exit to userspace on book3s. Similar return is required
for booke. EMULATE_DO_PAPR reads out to be confusing so it is
renamed to EMULATE_EXIT_USER.
Signed-off-by: NBharat Bhushan <bharat.bhushan@freescale.com>
Signed-off-by: NAlexander Graf <agraf@suse.de>

On mfspr/mtspr emulation path Book3E's MMUCFG SPR with value 1015 clashes
with G4's MSSSR0 SPR. Move MSSSR0 emulation from generic part to Books3S.
MSSSR0 also clashes with Book3S's DABRX SPR. DABRX was not explicitly
handled so Book3S execution flow will behave as before.
Signed-off-by: NMihai Caraman <mihai.caraman@freescale.com>
Signed-off-by: NAlexander Graf <agraf@suse.de>

When running on top of pHyp, the hypercall instruction "sc 1" goes
straight into pHyp without trapping in supervisor mode.

So if we want to support PAPR guest in this configuration we need to
add a second way of accessing PAPR hypercalls, preferably with the
exact same semantics except for the instruction.

So let's overlay an officially reserved instruction and emulate PAPR
hypercalls whenever we hit that one.
Signed-off-by: NAlexander Graf <agraf@suse.de>

This adds basic emulation of the PURR and SPURR registers.  We assume
we are emulating a single-threaded core, so these advance at the same
rate as the timebase.  A Linux kernel running on a POWER7 expects to
be able to access these registers and is not prepared to handle a
program interrupt on accessing them.

This also adds a very minimal emulation of the DSCR (data stream
control register).  Writes are ignored and reads return zero.
Signed-off-by: NPaul Mackerras <paulus@samba.org>
Signed-off-by: NAlexander Graf <agraf@suse.de>

When reading and writing SPRs, every SPR emulation piece had to read
or write the respective GPR the value was read from or stored in itself.

This approach is pretty prone to failure. What if we accidentally
implement mfspr emulation where we just do "break" and nothing else?
Suddenly we would get a random value in the return register - which is
always a bad idea.

So let's consolidate the generic code paths and only give the core
specific SPR handling code readily made variables to read/write from/to.

Functionally, this patch doesn't change anything, but it increases the
readability of the code and makes is less prone to bugs.
Signed-off-by: NAlexander Graf <agraf@suse.de>

Instructions on PPC are pretty similarly encoded. So instead of
every instruction emulation code decoding the instruction fields
itself, we can move that code to more generic places and rely on
the compiler to optimize the unused bits away.

This has 2 advantages. It makes the code smaller and it makes the
code less error prone, as the instruction fields are always
available, so accidental misusage is reduced.

Functionally, this patch doesn't change anything.
Signed-off-by: NAlexander Graf <agraf@suse.de>

Add a missing include to fix build
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

When running the 64-bit Book3s PR code without CONFIG_PREEMPT_NONE, we were
doing a few things wrong, most notably access to PACA fields without making
sure that the pointers stay stable accross the access (preempt_disable()).

This patch moves to_svcpu towards a get/put model which allows us to disable
preemption while accessing the shadow vcpu fields in the PACA. That way we
can run preemptible and everyone's happy!
Reported-by: NJörg Sommer <joerg@alea.gnuu.de>
Signed-off-by: NAlexander Graf <agraf@suse.de>
Signed-off-by: NAvi Kivity <avi@redhat.com>

Recent Linux versions use the CFAR and PURR SPRs, but don't really care about
their contents (yet). So for now, we can simply return 0 when the guest wants
to read them.
Signed-off-by: NAlexander Graf <agraf@suse.de>

We have 3 privilege levels: problem state, supervisor state and hypervisor
state. Each of them can access different SPRs, so we need to check on every
SPR if it's accessible in the respective mode.
Signed-off-by: NAlexander Graf <agraf@suse.de>

The current approach duplicates the spr->bat finding logic and makes it harder
to reuse the actually used variables. So let's move everything down to the spr
handler.
Signed-off-by: NAlexander Graf <agraf@suse.de>

The SRR0 and SRR1 registers contain cached values of the PC and MSR
respectively. They get written to by the hypervisor when an interrupt
occurs or directly by the kernel. They are also used to tell the rfi(d)
instruction where to jump to.

Because it only gets touched on defined events that, it's very simple to
share with the guest. Hypervisor and guest both have full r/w access.

This patch converts all users of the current field to the shared page.
Signed-off-by: NAlexander Graf <agraf@suse.de>
Signed-off-by: NAvi Kivity <avi@redhat.com>

The DAR register contains the address a data page fault occured at. This
register behaves pretty much like a simple data storage register that gets
written to on data faults. There is no hypervisor interaction required on
read or write.

This patch converts all users of the current field to the shared page.
Signed-off-by: NAlexander Graf <agraf@suse.de>
Signed-off-by: NAvi Kivity <avi@redhat.com>

The DSISR register contains information about a data page fault. It is fully
read/write from inside the guest context and we don't need to worry about
interacting based on writes of this register.

This patch converts all users of the current field to the shared page.
Signed-off-by: NAlexander Graf <agraf@suse.de>
Signed-off-by: NAvi Kivity <avi@redhat.com>

One of the most obvious registers to share with the guest directly is the
MSR. The MSR contains the "interrupts enabled" flag which the guest has to
toggle in critical sections.

So in order to bring the overhead of interrupt en- and disabling down, let's
put msr into the shared page. Keep in mind that even though you can fully read
its contents, writing to it doesn't always update all state. There are a few
safe fields that don't require hypervisor interaction. See the documentation
for a list of MSR bits that are safe to be set from inside the guest.
Signed-off-by: NAlexander Graf <agraf@suse.de>
Signed-off-by: NAvi Kivity <avi@redhat.com>

When we're on a paired single capable host, we can just always enable
paired singles and expose them to the guest directly.

This approach breaks when multiple VMs run and access PS concurrently,
but this should suffice until we get a proper framework for it in Linux.
Signed-off-by: NAlexander Graf <agraf@suse.de>
Signed-off-by: NAvi Kivity <avi@redhat.com>

Some code we had so far required defines and had code that was completely
Book3S_64 specific. Since we now opened book3s.c to Book3S_32 too, we need
to take care of these pieces.

So let's add some minor code where it makes sense to not go the Book3S_64
code paths and add compat defines on others.
Signed-off-by: NAlexander Graf <agraf@suse.de>
Signed-off-by: NAvi Kivity <avi@redhat.com>

We already have some inline fuctions we use to access vcpu or svcpu structs,
depending on whether we're on booke or book3s. Since we just put a few more
registers into the svcpu, we also need to make sure the respective callbacks
are available and get used.

So this patch moves direct use of the now in the svcpu struct fields to
inline function calls. While at it, it also moves the definition of those
inline function calls to respective header files for booke and book3s,
greatly improving readability.
Signed-off-by: NAlexander Graf <agraf@suse.de>
Signed-off-by: NAvi Kivity <avi@redhat.com>

We have quite some code that can be used by Book3S_32 and Book3S_64 alike,
so let's call it "Book3S" instead of "Book3S_64", so we can later on
use it from the 32 bit port too.
Signed-off-by: NAlexander Graf <agraf@suse.de>
Signed-off-by: NAvi Kivity <avi@redhat.com>

Mac OS X uses the dcba instruction. According to the specification it doesn't
guarantee any functionality, so let's just emulate it as nop.
Signed-off-by: NAlexander Graf <agraf@suse.de>
Signed-off-by: NAvi Kivity <avi@redhat.com>

On most systems we need to emulate dcbz when running 32 bit guests. So
far we've been rather slack, not giving correct DSISR values to the guest.

This patch makes the emulation more accurate, introducing a difference
between "page not mapped" and "write protection fault". While at it, it
also speeds up dcbz emulation by an order of magnitude by using kmap.
Signed-off-by: NAlexander Graf <agraf@suse.de>
Signed-off-by: NAvi Kivity <avi@redhat.com>

Mac OS X has some applications - namely the Finder - that require alignment
interrupts to work properly. So we need to implement them.

But the spec for 970 and 750 also looks different. While 750 requires the
DSISR and DAR fields to reflect some instruction bits (DSISR) and the fault
address (DAR), the 970 declares this as an optional feature. So we need
to reconstruct DSISR and DAR manually.
Signed-off-by: NAlexander Graf <agraf@suse.de>
Signed-off-by: NAvi Kivity <avi@redhat.com>

BATs can't only be written to, you can also read them out!
So let's implement emulation for reading BAT values again.

While at it, I also made BAT setting flush the segment cache,
so we're absolutely sure there's no MMU state left when writing
BATs.
Signed-off-by: NAlexander Graf <agraf@suse.de>
Signed-off-by: NAvi Kivity <avi@redhat.com>

We emulate the mfsrin instruction already, that passes the SR number
in a register value. But we lacked support for mfsr that encoded the
SR number in the opcode.

So let's implement it.
Signed-off-by: NAlexander Graf <agraf@suse.de>
Signed-off-by: NAvi Kivity <avi@redhat.com>

The one big thing about the Gekko is paired singles.

Paired singles are an extension to the instruction set, that adds 32 single
precision floating point registers (qprs), some SPRs to modify the behavior
of paired singled operations and instructions to deal with qprs to the
instruction set.

Unfortunately, it also changes semantics of existing operations that affect
single values in FPRs. In most cases they get mirrored to the coresponding
QPR.

Thanks to that we need to emulate all FPU operations and all the new paired
single operations too.

In order to achieve that, we use the just introduced FPU call helpers to
call the real FPU whenever the guest wants to modify an FPR. Additionally
we also fix up the QPR values along the way.

That way we can execute paired single FPU operations without implementing a
soft fpu.
Signed-off-by: NAlexander Graf <agraf@suse.de>
Signed-off-by: NAvi Kivity <avi@redhat.com>

BATs didn't work. Well, they did, but only up to BAT3. As soon as we
came to BAT4 the offset calculation was screwed up and we ended up
overwriting BAT0-3.

Fortunately, Linux hasn't been using BAT4+. It's still a good
idea to write correct code though.
Signed-off-by: NAlexander Graf <agraf@suse.de>
Signed-off-by: NAvi Kivity <avi@redhat.com>

The Book3S KVM implementation contains some helper functions to load and store
data from and to virtual addresses.

Unfortunately, this helper used to keep the physical address it so nicely
found out for us to itself. So let's change that and make it return the
physical address it resolved.
Signed-off-by: NAlexander Graf <agraf@suse.de>
Signed-off-by: NAvi Kivity <avi@redhat.com>

The Book3S_32 specifications allows for two instructions to modify segment
registers: mtsrin and mtsr.

Most normal operating systems use mtsrin, because it allows to define which
segment it wants to change using a register. But since I was trying to run
an embedded guest, it turned out to be using mtsr with hardcoded values.

So let's also emulate mtsr. It's a valid instruction after all.
Signed-off-by: NAlexander Graf <agraf@suse.de>
Signed-off-by: NAvi Kivity <avi@redhat.com>

The Gekko has some SPR values that differ from other PPC core values and
also some additional ones.

Let's add support for them in our mfspr/mtspr emulator.
Signed-off-by: NAlexander Graf <agraf@suse.de>
Signed-off-by: NAvi Kivity <avi@redhat.com>

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: NAlexander Graf <agraf@suse.de>
Signed-off-by: NAvi Kivity <avi@redhat.com>

Currently userspace has no chance to find out which virtual address space we're
in and resolve addresses. While that is a big problem for migration, it's also
unpleasent when debugging, as gdb and the monitor don't work on virtual
addresses.

This patch exports enough of the MMU segment state to userspace to make
debugging work and thus also includes the groundwork for migration.
Signed-off-by: NAlexander Graf <agraf@suse.de>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

There are generic parts of PowerPC that can be shared across all
implementations and specific parts that only apply to BookE or desktop PPCs.

This patch adds emulation for desktop specific opcodes that don't apply
to BookE CPUs.
Signed-off-by: NAlexander Graf <agraf@suse.de>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>