Currently during KVM initialization on POWER, kvm_fixup_page_sizes()
rewrites a bunch of information in the cpu state to reflect the
capabilities of the host MMU and KVM. This overwrites the information
that's already there reflecting how the TCG implementation of the MMU will
operate.
This means that we can get guest-visibly different behaviour between KVM
and TCG (and between different KVM implementations). That's bad. It also
prevents migration between KVM and TCG.
The pseries machine type now has filtering of the pagesizes it allows the
guest to use which means it can present a consistent model of the MMU
across all accelerators.
So, we can now replace kvm_fixup_page_sizes() with kvm_check_mmu() which
merely verifies that the expected cpu model can be faithfully handled by
KVM, rather than updating the cpu model to match KVM.
We call kvm_check_mmu() from the spapr cpu reset code. This is a hack:
conceptually it makes more sense where fixup_page_sizes() was - in the KVM
cpu init path. However, doing that would require moving the platform's
pagesize filtering much earlier, which would require a lot of work making
further adjustments. There wouldn't be a lot of concrete point to doing
that, since the only KVM implementation which has the awkward MMU
restrictions is KVM HV, which can only work with an spapr guest anyway.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Reviewed-by: Cédric Le Goater <clg@kaod.org>
The way we used to handle KVM allowable guest pagesizes for PAPR guests
required some convoluted checking of memory attached to the guest.
The allowable pagesizes advertised to the guest cpus depended on the memory
which was attached at boot, but then we needed to ensure that any memory
later hotplugged didn't change which pagesizes were allowed.
Now that we have an explicit machine option to control the allowable
maximum pagesize we can simplify this. We just check all memory backends
against that declared pagesize. We check base and cold-plugged memory at
reset time, and hotplugged memory at pre_plug() time.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Reviewed-by: Cédric Le Goater <clg@kaod.org>
Reviewed-by: Greg Kurz <groug@kaod.org>
KVM HV has a restriction that for HPT mode guests, guest pages must be hpa
contiguous as well as gpa contiguous. We have to account for that in
various places. We determine whether we're subject to this restriction
from the SMMU information exposed by KVM.
Planned cleanups to the way we handle this will require knowing whether
this restriction is in play in wider parts of the code. So, expose a
helper function which returns it.
This does mean some redundant calls to kvm_get_smmu_info(), but they'll go
away again with future cleanups.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Reviewed-by: Greg Kurz <groug@kaod.org>
Reviewed-by: Cédric Le Goater <clg@kaod.org>
Current POWER cpus allow for a VRMA, a special mapping which describes a
guest's view of memory when in real mode (MMU off, from the guest's point
of view). Older cpus didn't have that which meant that to support a guest
a special host-contiguous region of memory was needed to give the guest its
Real Mode Area (RMA).
KVM used to provide special calls to allocate a contiguous RMA for those
cases. This was useful in the early days of KVM on Power to allow it to be
tested on PowerPC 970 chips as used in Macintosh G5 machines. Now, those
machines are so old as to be almost irrelevant.
The normal qemu deprecation process would require this to be marked
deprecated then removed in 2 releases. However, this can only be used
with corresponding support in the host kernel - which was dropped
years ago (in c17b98cf "KVM: PPC: Book3S HV: Remove code for PPC970
processors" of 2014-12-03 to be precise). Therefore it should be ok
to drop this immediately.
Just to be clear this only affects *KVM HV* guests with PowerPC 970,
and those already require an ancient host kernel. TCG and KVM PR
guests with PowerPC 970 should still work.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Acked-by: Thomas Huth <thuth@redhat.com>
In order to enable TCE operations support in KVM, we have to inform
the KVM about VFIO groups being attached to specific LIOBNs;
the necessary bits are implemented already by IOMMU MR and VFIO.
This defines get_attr() for the SPAPR TCE IOMMU MR which makes VFIO
call the KVM_DEV_VFIO_GROUP_SET_SPAPR_TCE ioctl and establish
LIOBN-to-IOMMU link.
This changes spapr_tce_set_need_vfio() to avoid TCE table reallocation
if the kernel supports the TCE acceleration.
Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Acked-by: David Gibson <david@gibson.dropbear.id.au>
[aw - remove unnecessary sys/ioctl.h include]
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Add three new kvm capabilities used to represent the level of host support
for three corresponding workarounds.
Host support for each of the capabilities is queried through the
new ioctl KVM_PPC_GET_CPU_CHAR which returns four uint64 quantities. The
first two, character and behaviour, represent the available
characteristics of the cpu and the behaviour of the cpu respectively.
The second two, c_mask and b_mask, represent the mask of known bits for
the character and beheviour dwords respectively.
Signed-off-by: Suraj Jitindar Singh <sjitindarsingh@gmail.com>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
[dwg: Correct some compile errors due to name change in final kernel
patch version]
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
When constructing the "host" cpu class we modify whether the VMX and VSX
vector extensions and DFP (Decimal Floating Point) are available
based on whether KVM can support those instructions. This can depend on
policy in the host kernel as well as on the actual host cpu capabilities.
However, the way we probe for this is not very nice: we explicitly check
the host's device tree. That works in practice, but it's not really
correct, since the device tree is a property of the host kernel's platform
which we don't really know about. We get away with it because the only
modern POWER platforms happen to encode VMX, VSX and DFP availability in
the device tree in the same way.
Arguably we should have an explicit KVM capability for this, but we haven't
needed one so far. Barring specific KVM policies which don't yet exist,
each of these instruction classes will be available in the guest if and
only if they're available in the qemu userspace process. We can determine
that from the ELF AUX vector we're supplied with.
Once reworked like this, there are no more callers for kvmppc_get_vmx() and
kvmppc_get_dfp() so remove them.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Reviewed-by: Greg Kurz <groug@kaod.org>
When running with KVM PR, if a new HPT is allocated we need to inform
KVM about the HPT address and size. This is currently done by hacking
the value of SDR1 and pushing it to KVM in several places.
Also, migration breaks the guest since it is very unlikely the HPT has
the same address in source and destination, but we push the incoming
value of SDR1 to KVM anyway.
This patch introduces a new virtual hypervisor hook so that the spapr
code can provide the correct value of SDR1 to be pushed to KVM each
time kvmppc_put_books_sregs() is called.
It allows to get rid of all the hacking in the spapr/kvmppc code and
it fixes migration of nested KVM PR.
Suggested-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Greg Kurz <groug@kaod.org>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
The use of KVM_PPC_GET_HTAB_FD is open-coded in kvmppc_read_hptes()
and kvmppc_write_hpte().
This patch modifies kvmppc_get_htab_fd() so that it can be used
everywhere we need to access the in-kernel htab:
- add an index argument
=> only kvmppc_read_hptes() passes an actual index, all other users
pass 0
- add an errp argument to propagate error messages to the caller.
=> spapr migration code prints the error
=> hpte helpers pass &error_abort to keep the current behavior
of hw_error()
While here, this also fixes a bug in kvmppc_write_hpte() so that it
opens the htab fd for writing instead of reading as it currently does.
This never broke anything because we currently never call this code,
as explained in the changelog of commit c138593380:
"This support updating htab managed by the hypervisor. Currently
we don't have any user for this feature. This actually bring the
store_hpte interface in-line with the load_hpte one. We may want
to use this when we want to emulate henter hcall in qemu for HV
kvm."
The above is still true today.
Signed-off-by: Greg Kurz <groug@kaod.org>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
It never got used since its introduction (commit 7c43bca004).
Signed-off-by: Greg Kurz <groug@kaod.org>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Replace
"-" TYPE_POWERPC_CPU
when composing cpu type name from cpu model string literal
and the same pattern in format strings with
POWERPC_CPU_TYPE_SUFFIX and POWERPC_CPU_TYPE_NAME(model)
macroses like we do in x86.
Later POWERPC_CPU_TYPE_NAME() will be used to define default
cpu type per machine type and as bonus it will be consistent
and easy grep-able pattern across all other targets that I'm
plannig to treat the same way.
Signed-off-by: Igor Mammedov <imammedo@redhat.com>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
KVM now allows writing to KVM_CAP_PPC_SMT which has previously been
read only. Doing so causes KVM to act, for that VM, as if the host's
SMT mode was the given value. This is particularly important on Power
9 systems because their default value is 1, but they are able to
support values up to 8.
This patch introduces a way to control this capability via a new
machine property called VSMT ("Virtual SMT"). If the value is not set
on the command line a default is chosen that is, when possible,
compatible with legacy systems.
Note that the intialization of KVM_CAP_PPC_SMT has changed slightly
because it has changed (in KVM) from a global capability to a
VM-specific one. This won't cause a problem on older KVMs because VM
capabilities fall back to global ones.
Signed-off-by: Sam Bobroff <sam.bobroff@au1.ibm.com>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Commit d5fc133eed ("ppc: Rework CPU compatibility testing
across migration") changed the way cpu_post_load behaves with
the PVR setting, causing an unexpected bug in KVM-HV migrations
between hosts that are compatible (POWER8 and POWER8E, for example).
Even with pvr_match() returning true, the guest freezes right after
cpu_post_load. The reason is that the guest kernel can't handle a
different PVR value other that the running host in KVM_SET_SREGS.
In [1] it was discussed the possibility of a new KVM capability
that would indicate that the guest kernel can handle a different
PVR in KVM_SET_SREGS. Even if such feature is implemented, there is
still the problem with older kernels that will not have this capability
and will fail to migrate.
This patch implements a workaround for that scenario. If running
with KVM, check if the guest kernel does not have the capability
(named here as 'cap_ppc_pvr_compat'). If it doesn't, calls
kvmppc_is_pr() to see if the guest is running in KVM-HV. If all this
happens, set env->spr[SPR_PVR] to the same value as the current
host PVR. This ensures that we allow migrations with 'close enough'
PVRs to still work in KVM-HV but also makes the code ready for
this new KVM capability when it is done.
A new function called 'kvmppc_pvr_workaround_required' was created
to encapsulate the conditions said above and to avoid calling too
many kvm.c internals inside cpu_post_load.
[1] https://lists.gnu.org/archive/html/qemu-ppc/2017-06/msg00503.html
Signed-off-by: Daniel Henrique Barboza <danielhb@linux.vnet.ibm.com>
[dwg: Fix for the case of using TCG on a PPC host]
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
So far, qemu implements the PAPR Hash Page Table (HPT) resizing extension
with TCG. The same implementation will work with KVM PR, but we don't
currently allow that. For KVM HV we can only implement resizing with the
assistance of the host kernel, which needs a new capability and ioctl()s.
This patch adds support for testing the new KVM capability and implementing
the resize in terms of KVM facilities when necessary. If we're running on
a kernel which doesn't have the new capability flag at all, we fall back to
testing for PR vs. HV KVM using the same hack that we already use in a
number of places for older kernels.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
This introduces stub implementations of the H_RESIZE_HPT_PREPARE and
H_RESIZE_HPT_COMMIT hypercalls which we hope to add in a PAPR
extension to allow run time resizing of a guest's hash page table. It
also adds a new machine property for controlling whether this new
facility is available.
For now we only allow resizing with TCG, allowing it with KVM will require
kernel changes as well.
Finally, it adds a new string to the hypertas property in the device
tree, advertising to the guest the availability of the HPT resizing
hypercalls. This is a tentative suggested value, and would need to be
standardized by PAPR before being merged.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Reviewed-by: Suraj Jitindar Singh <sjitindarsingh@gmail.com>
Reviewed-by: Laurent Vivier <lvivier@redhat.com>
This function has three implementations. Two are stubs that do nothing
and the third one only passes the obj_path argument to:
Object *object_resolve_path(const char *path, bool *ambiguous);
Signed-off-by: Greg Kurz <groug@kaod.org>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
This enables in-kernel handling of H_PUT_TCE_INDIRECT and
H_STUFF_TCE hypercalls. The host kernel support is there since v4.6,
in particular d3695aa4f452
("KVM: PPC: Add support for multiple-TCE hcalls").
H_PUT_TCE is already accelerated and does not need any special enablement.
Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
The H_REGISTER_PROCESS_TABLE H_CALL is used by a guest to indicate to the
hypervisor where in memory its process table is and how translation should
be performed using this process table.
Provide the implementation of this H_CALL for a guest.
We first check for invalid flags, then parse the flags to determine the
operation, and then check the other parameters for valid values based on
the operation (register new table/deregister table/maintain registration).
The process table is then stored in the appropriate location and registered
with the hypervisor (if running under KVM), and the LPCR_[UPRT/GTSE] bits
are updated as required.
Signed-off-by: Suraj Jitindar Singh <sjitindarsingh@gmail.com>
Signed-off-by: Sam Bobroff <sam.bobroff@au1.ibm.com>
[dwg: Correct missing prototype and uninitialized variable]
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Query and cache the value of two new KVM capabilities that indicate
KVM's support for new radix and hash modes of the MMU.
Signed-off-by: Sam Bobroff <sam.bobroff@au1.ibm.com>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
KVM_CAP_SPAPR_TCE capability allows creating TCE tables in KVM which
allows having in-kernel acceleration for H_PUT_TCE_xxx hypercalls.
However it only supports 32bit DMA windows at zero bus offset.
There is a new KVM_CAP_SPAPR_TCE_64 capability which supports 64bit
window size, variable page size and bus offset.
This makes use of the new capability. The kernel headers are already
updated as the kernel support went in to v4.6.
Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
When a 'pseries' guest is running with KVM-HV, the guest's hashed page
table (HPT) is stored within the host kernel, so it is not directly
accessible to qemu. Most of the time, qemu doesn't need to access it:
we're using the hardware MMU, and KVM itself implements the guest
hypercalls for manipulating the HPT.
However, qemu does need access to the in-KVM HPT to implement
get_phys_page_debug() for the benefit of the gdbstub, and maybe for
other debug operations.
To allow this, 7c43bca "target-ppc: Fix page table lookup with kvm
enabled" added kvmppc_hash64_read_pteg() to target/ppc/kvm.c to read
in a batch of HPTEs from the KVM table. Unfortunately, there are a
couple of problems with this:
First, the name of the function implies it always reads a whole PTEG
from the HPT, but in fact in some cases it's used to grab individual
HPTEs (which ends up pulling 8 HPTEs, not aligned to a PTEG from the
kernel).
Second, and more importantly, the code to read the HPTEs from KVM is
simply wrong, in general. The data from the fd that KVM provides is
designed mostly for compact migration rather than this sort of one-off
access, and so needs some decoding for this purpose. The current code
will work in some cases, but if there are invalid HPTEs then it will
not get sane results.
This patch rewrite the HPTE reading function to have a simpler
interface (just read n HPTEs into a caller provided buffer), and to
correctly decode the stream from the kernel.
For consistency we also clean up the similar function for altering
HPTEs within KVM (introduced in c138593 "target-ppc: Update
ppc_hash64_store_hpte to support updating in-kernel htab").
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
On POWER, the valid page sizes that the guest can use are bound
to the CPU and not to the memory region. QEMU already has some
fancy logic to find out the right maximum memory size to tell
it to the guest during boot (see getrampagesize() in the file
target/ppc/kvm.c for more information).
However, once we're booted and the guest is using huge pages
already, it is currently still possible to hot-plug memory regions
that does not support huge pages - which of course does not work
on POWER, since the guest thinks that it is possible to use huge
pages everywhere. The KVM_RUN ioctl will then abort with -EFAULT,
QEMU spills out a not very helpful error message together with
a register dump and the user is annoyed that the VM unexpectedly
died.
To avoid this situation, we should check the page size of hot-plugged
DIMMs to see whether it is possible to use it in the current VM.
If it does not fit, we can print out a better error message and
refuse to add it, so that the VM does not die unexpectely and the
user has a second chance to plug a DIMM with a matching memory
backend instead.
Buglink: https://bugzilla.redhat.com/show_bug.cgi?id=1419466
Signed-off-by: Thomas Huth <thuth@redhat.com>
[dwg: Fix a build error on 32-bit builds with KVM]
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
The 'cpu_version' field in PowerPCCPU is badly named. It's named after the
'cpu-version' device tree property where it is advertised, but that meaning
may not be obvious in most places it appears.
Worse, it doesn't even really correspond to that device tree property. The
property contains either the processor's PVR, or, if the CPU is running in
a compatibility mode, a special "logical PVR" representing which mode.
Rename the cpu_version field, and a number of related variables to
compat_pvr to make this clearer.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Reviewed-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Reviewed-by: Thomas Huth <thuth@redhat.com>
These are not needed since linux-headers/ provides up-to-date definitions.
The constants are in linux-headers/asm-powerpc/kvm.h.
The sole users, hw/intc/xics_kvm.c and target/ppc/kvm.c, include asm/kvm.h
via sysemu/kvm.h->linux/kvm.h.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
We've currently got 18 architectures in QEMU, and thus 18 target-xxx
folders in the root folder of the QEMU source tree. More architectures
(e.g. RISC-V, AVR) are likely to be included soon, too, so the main
folder of the QEMU sources slowly gets quite overcrowded with the
target-xxx folders.
To disburden the main folder a little bit, let's move the target-xxx
folders into a dedicated target/ folder, so that target-xxx/ simply
becomes target/xxx/ instead.
Acked-by: Laurent Vivier <laurent@vivier.eu> [m68k part]
Acked-by: Bastian Koppelmann <kbastian@mail.uni-paderborn.de> [tricore part]
Acked-by: Michael Walle <michael@walle.cc> [lm32 part]
Acked-by: Cornelia Huck <cornelia.huck@de.ibm.com> [s390x part]
Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com> [s390x part]
Acked-by: Eduardo Habkost <ehabkost@redhat.com> [i386 part]
Acked-by: Artyom Tarasenko <atar4qemu@gmail.com> [sparc part]
Acked-by: Richard Henderson <rth@twiddle.net> [alpha part]
Acked-by: Max Filippov <jcmvbkbc@gmail.com> [xtensa part]
Reviewed-by: David Gibson <david@gibson.dropbear.id.au> [ppc part]
Acked-by: Edgar E. Iglesias <edgar.iglesias@xilinx.com> [crisµblaze part]
Acked-by: Guan Xuetao <gxt@mprc.pku.edu.cn> [unicore32 part]
Signed-off-by: Thomas Huth <thuth@redhat.com>
