LoongArch KVM changes for v6.9 * Set reserved bits as zero in CPUCFG. * Start SW timer only when vcpu is blocking. * Do not restart SW timer when it is expired. * Remove unnecessary CSR register saving during enter guest.
Since all architectures (for historical reasons) have to define struct kvm_guest_debug_arch, and since userspace has to check KVM_CHECK_EXTENSION(KVM_CAP_SET_GUEST_DEBUG) anyway, there is no advantage in masking the capability #define itself. Remove the #define __KVM_HAVE_GUEST_DEBUG from architecture-specific headers. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
While this in principle breaks the appearance of KVM_PPC_* ioctls on architectures other than powerpc, this seems unlikely to be a problem considering that there are already many "struct kvm_ppc_*" definitions in arch/powerpc/include/uapi. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Some PAPR system parameter values are formatted by firmware as
nul-terminated strings (e.g. LPAR name, shared processor attributes).
But the values returned for other parameters, such as processor module
info and TLB block invalidate characteristics, are binary data with
parameter-specific layouts. So char[] isn't the appropriate type for
the general case. Use u8/__u8.
Signed-off-by: Nathan Lynch <nathanl@linux.ibm.com>
Fixes: 905b9e48786e ("powerpc/pseries/papr-sysparm: Expose character device to user space")
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20240202-papr-sysparm-ioblock-data-use-u8-v1-1-f5c6c89f65ec@linux.ibm.com
Until now the papr_sysparm APIs have been kernel-internal. But user space needs access to PAPR system parameters too. The only method available to user space today to get or set system parameters is using sys_rtas() and /dev/mem to pass RTAS-addressable buffers between user space and firmware. This is incompatible with lockdown and should be deprecated. So provide an alternative ABI to user space in the form of a /dev/papr-sysparm character device with just two ioctl commands (get and set). The data payloads involved are small enough to fit in the ioctl argument buffer, making the code relatively simple. Exposing the system parameters through sysfs has been considered but it would be too awkward: * The kernel currently does not have to contain an exhaustive list of defined system parameters. This is a convenient property to maintain because we don't have to update the kernel whenever a new parameter is added to PAPR. Exporting a named attribute in sysfs for each parameter would negate this. * Some system parameters are text-based and some are not. * Retrieval of at least one system parameter requires input data, which a simple read-oriented interface can't support. Signed-off-by: Nathan Lynch <nathanl@linux.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://msgid.link/20231212-papr-sys_rtas-vs-lockdown-v6-11-e9eafd0c8c6c@linux.ibm.com
PowerVM LPARs may retrieve Vital Product Data (VPD) for system
components using the ibm,get-vpd RTAS function.
We can expose this to user space with a /dev/papr-vpd character
device, where the programming model is:
struct papr_location_code plc = { .str = "", }; /* obtain all VPD */
int devfd = open("/dev/papr-vpd", O_RDONLY);
int vpdfd = ioctl(devfd, PAPR_VPD_CREATE_HANDLE, &plc);
size_t size = lseek(vpdfd, 0, SEEK_END);
char *buf = malloc(size);
pread(devfd, buf, size, 0);
When a file descriptor is obtained from ioctl(PAPR_VPD_CREATE_HANDLE),
the file contains the result of a complete ibm,get-vpd sequence. The
file contents are immutable from the POV of user space. To get a new
view of the VPD, the client must create a new handle.
This design choice insulates user space from most of the complexities
that ibm,get-vpd brings:
* ibm,get-vpd must be called more than once to obtain complete
results.
* Only one ibm,get-vpd call sequence should be in progress at a time;
interleaved sequences will disrupt each other. Callers must have a
protocol for serializing their use of the function.
* A call sequence in progress may receive a "VPD changed, try again"
status, requiring the client to abandon the sequence and start
over.
The memory required for the VPD buffers seems acceptable, around 20KB
for all VPD on one of my systems. And the value of the
/rtas/ibm,vpd-size DT property (the estimated maximum size of VPD) is
consistently 300KB across various systems I've checked.
I've implemented support for this new ABI in the rtas_get_vpd()
function in librtas, which the vpdupdate command currently uses to
populate its VPD database. I've verified that an unmodified vpdupdate
binary generates an identical database when using a librtas.so that
prefers the new ABI.
Along with the papr-vpd.h header exposed to user space, this
introduces a common papr-miscdev.h uapi header to share a base ioctl
ID with similar drivers to come.
Tested-by: Michal Suchánek <msuchanek@suse.de>
Signed-off-by: Nathan Lynch <nathanl@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20231212-papr-sys_rtas-vs-lockdown-v6-9-e9eafd0c8c6c@linux.ibm.com
The HASHKEYR register contains a secret per-process key to enable unique hashes per process. In general it should not be exposed to userspace at all and a regular process has no need to know its key. However, checkpoint restore in userspace (CRIU) functionality requires that a process be able to set the HASHKEYR of another process, otherwise existing hashes on the stack would be invalidated by a new random key. Exposing HASHKEYR in this way also makes it appear in core dumps, which is a security concern. Multiple threads may share a key, for example just after a fork() call, where the kernel cannot know if the child is going to return back along the parent's stack. If such a thread is coerced into making a core dump, then the HASHKEYR value will be readable and able to be used against all other threads sharing that key, effectively undoing any protection offered by hashst/hashchk. Therefore we expose HASHKEYR to ptrace when CONFIG_CHECKPOINT_RESTORE is enabled, providing a choice of increased security or migratable ROP protected processes. This is similar to how ARM exposes its PAC keys. Signed-off-by: Benjamin Gray <bgray@linux.ibm.com> Reviewed-by: Russell Currey <ruscur@russell.cc> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://msgid.link/20230616034846.311705-8-bgray@linux.ibm.com
The DEXCR register is of interest when ptracing processes. Currently it is static, but eventually will be dynamically controllable by a process. If a process can control its own, then it is useful for it to be ptrace-able to (e.g., for checkpoint-restore functionality). It is also relevant to core dumps (the NPHIE aspect in particular), which use the ptrace mechanism (or is it the other way around?) to decide what to dump. The HDEXCR is useful here too, as the NPHIE aspect may be set in the HDEXCR without being set in the DEXCR. Although the HDEXCR is per-cpu and we don't track it in the task struct (it's useless in normal operation), it would be difficult to imagine why a hypervisor would set it to different values within a guest. A hypervisor cannot safely set NPHIE differently at least, as that would break programs. Expose a read-only view of the userspace DEXCR and HDEXCR to ptrace. The HDEXCR is always readonly, and is useful for diagnosing the core dumps (as the HDEXCR may set NPHIE without the DEXCR setting it). Signed-off-by: Benjamin Gray <bgray@linux.ibm.com> Reviewed-by: Russell Currey <ruscur@russell.cc> [mpe: Use lower_32_bits() rather than open coding] Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://msgid.link/20230616034846.311705-7-bgray@linux.ibm.com
Build modules using PCREL addressing when CONFIG_PPC_KERNEL_PCREL=y.
- The module loader must handle several new relocation types:
* R_PPC64_REL24_NOTOC is a function call handled like R_PPC_REL24, but
does not restore r2 upon return. The external function call stub is
changed to use pcrel addressing to load the function pointer rather
than based on the module TOC.
* R_PPC64_GOT_PCREL34 is a reference to external data. A GOT table
must be built by hand, because the linker adds this during the final
link (which is not done for kernel modules). The GOT table is built
similarly to the way the external function call stub table is. This
section is called .mygot because .got has a special meaning for the
linker and can become upset.
* R_PPC64_PCREL34 is used for local data addressing, but there is a
special case where the percpu section is moved at load-time to the
percpu area which is out of range of this relocation. This requires
the PCREL34 relocations are converted to use GOT_PCREL34 addressing.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
[mpe: Some coding style & formatting fixups]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20230408021752.862660-7-npiggin@gmail.com
Trying to build a .c file that includes <linux/bpf_perf_event.h>:
$ cat test_bpf_headers.c
#include <linux/bpf_perf_event.h>
throws the below error:
/usr/include/linux/bpf_perf_event.h:14:28: error: field ‘regs’ has incomplete type
14 | bpf_user_pt_regs_t regs;
| ^~~~
This is because we typedef bpf_user_pt_regs_t to 'struct user_pt_regs'
in arch/powerpc/include/uaps/asm/bpf_perf_event.h, but 'struct
user_pt_regs' is not exposed to userspace.
Powerpc has both pt_regs and user_pt_regs structures. However, unlike
arm64 and s390, we expose user_pt_regs to userspace as just 'pt_regs'.
As such, we should typedef bpf_user_pt_regs_t to 'struct pt_regs' for
userspace.
Within the kernel though, we want to typedef bpf_user_pt_regs_t to
'struct user_pt_regs'.
Remove arch/powerpc/include/uapi/asm/bpf_perf_event.h so that the
uapi/asm-generic version of the header is exposed to userspace.
Introduce arch/powerpc/include/asm/bpf_perf_event.h so that we can
typedef bpf_user_pt_regs_t to 'struct user_pt_regs' for use within the
kernel.
Note that this was not showing up with the bpf selftest build since
tools/include/uapi/asm/bpf_perf_event.h didn't include the powerpc
variant.
Fixes: a6460b03f945ee ("powerpc/bpf: Fix broken uapi for BPF_PROG_TYPE_PERF_EVENT")
Cc: stable@vger.kernel.org # v4.20+
Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
[mpe: Use typical naming for header include guard]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220627191119.142867-1-naveen.n.rao@linux.vnet.ibm.com