The code in setup_rt_frame reads two words at haddr, but locks only one.
This patch fixes it to lock both.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Acked-by: Helge Deller <deller@gmx.de>
Cc: qemu-stable@nongnu.org
Signed-off-by: Helge Deller <deller@gmx.de>
qemu-hppa may crash when delivering a signal. It can be demonstrated with
this program. Compile the program with "hppa-linux-gnu-gcc -O2 signal.c"
and run it with "qemu-hppa -one-insn-per-tb a.out". It reports that the
address of the flag is 0xb4 and it crashes when attempting to touch it.
#include <stdio.h>
#include <stdlib.h>
#include <sys/time.h>
#include <signal.h>
sig_atomic_t flag;
void sig(int n)
{
printf("&flag: %p\n", &flag);
flag = 1;
}
int main(void)
{
struct sigaction sa;
struct itimerval it;
sa.sa_handler = sig;
sigemptyset(&sa.sa_mask);
sa.sa_flags = SA_RESTART;
if (sigaction(SIGALRM, &sa, NULL)) perror("sigaction"), exit(1);
it.it_interval.tv_sec = 0;
it.it_interval.tv_usec = 100;
it.it_value.tv_sec = it.it_interval.tv_sec;
it.it_value.tv_usec = it.it_interval.tv_usec;
if (setitimer(ITIMER_REAL, &it, NULL)) perror("setitimer"), exit(1);
while (1) {
}
}
The reason for the crash is that the signal handling routine doesn't clear
the 'N' flag in the PSW. If the signal interrupts a thread when the 'N'
flag is set, the flag remains set at the beginning of the signal handler
and the first instruction of the signal handler is skipped.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Acked-by: Helge Deller <deller@gmx.de>
Cc: qemu-stable@nongnu.org
Signed-off-by: Helge Deller <deller@gmx.de>
Wire up the hppa diag instruction to support Block-TLBs
when called with the 0x100 value.
The diag_btlb() helper function does all necessary steps
to emulate the PDC BTLB firmware function, which includes
providing BTLB info, adding a new BTLB, deleting a BTLB
and removing all BTLBs.
Signed-off-by: Helge Deller <deller@gmx.de>
Hi,
"Host Memory Backends" and "Memory devices" queue ("mem"):
- Support and document VM templating with R/O files using a new "rom"
parameter for memory-backend-file
- Some cleanups and fixes around NVDIMMs and R/O file handling for guest
RAM
- Optimize ioeventfd updates by skipping address spaces that are not
applicable
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# -----END PGP SIGNATURE-----
# gpg: Signature made Tue 19 Sep 2023 06:25:45 EDT
# gpg: using RSA key 1BD9CAAD735C4C3A460DFCCA4DDE10F700FF835A
# gpg: issuer "david@redhat.com"
# gpg: Good signature from "David Hildenbrand <david@redhat.com>" [unknown]
# gpg: aka "David Hildenbrand <davidhildenbrand@gmail.com>" [full]
# gpg: aka "David Hildenbrand <hildenbr@in.tum.de>" [unknown]
# gpg: WARNING: The key's User ID is not certified with a trusted signature!
# gpg: There is no indication that the signature belongs to the owner.
# Primary key fingerprint: 1BD9 CAAD 735C 4C3A 460D FCCA 4DDE 10F7 00FF 835A
* tag 'mem-2023-09-19' of https://github.com/davidhildenbrand/qemu:
memory: avoid updating ioeventfds for some address_space
machine: Improve error message when using default RAM backend id
softmmu/physmem: Hint that "readonly=on,rom=off" exists when opening file R/W for private mapping fails
docs: Start documenting VM templating
docs: Don't mention "-mem-path" in multi-process.rst
softmmu/physmem: Never return directories from file_ram_open()
softmmu/physmem: Fail creation of new files in file_ram_open() with readonly=true
softmmu/physmem: Bail out early in ram_block_discard_range() with readonly files
softmmu/physmem: Remap with proper protection in qemu_ram_remap()
backends/hostmem-file: Add "rom" property to support VM templating with R/O files
softmmu/physmem: Distinguish between file access mode and mmap protection
nvdimm: Reject writing label data to ROM instead of crashing QEMU
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
ppc patch queue for 2023-09-18:
In this short queue we're making two important changes:
- Nicholas Piggin is now the qemu-ppc maintainer. Cédric Le Goater and
Daniel Barboza will act as backup during Nick's transition to this new
role.
- Support for NVIDIA V100 GPU with NVLink2 is dropped from qemu-ppc.
Linux removed the same support back in 5.13, we're following suit now.
A xive Coverity fix is also included.
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# -----END PGP SIGNATURE-----
# gpg: Signature made Mon 18 Sep 2023 09:24:44 EDT
# gpg: using EDDSA key 17EBFF9923D01800AF2838193CD9CA96DE033164
# gpg: issuer "danielhb413@gmail.com"
# gpg: Good signature from "Daniel Henrique Barboza <danielhb413@gmail.com>" [unknown]
# gpg: WARNING: The key's User ID is not certified with a trusted signature!
# gpg: There is no indication that the signature belongs to the owner.
# Primary key fingerprint: 17EB FF99 23D0 1800 AF28 3819 3CD9 CA96 DE03 3164
* tag 'pull-ppc-20230918' of https://gitlab.com/danielhb/qemu:
spapr: Remove support for NVIDIA V100 GPU with NVLink2
ppc/xive: Fix uint32_t overflow
MAINTAINERS: Nick Piggin PPC maintainer, other PPC changes
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
When updating ioeventfds, we need to iterate all address spaces,
but some address spaces do not register eventfd_add|del call when
memory_listener_register() and they do nothing when updating ioeventfds.
So we can skip these AS in address_space_update_ioeventfds().
The overhead of memory_region_transaction_commit() can be significantly
reduced. For example, a VM with 8 vhost net devices and each one has
64 vectors, can reduce the time spent on memory_region_transaction_commit by 20%.
Message-ID: <20230830032906.12488-1-hongmianquan@bytedance.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: hongmianquan <hongmianquan@bytedance.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
For migration purposes, users might want to reuse the default RAM
backend id, but specify a different memory backend.
For example, to reuse "pc.ram" on q35, one has to set
-machine q35,memory-backend=pc.ram
Only then, can a memory backend with the id "pc.ram" be created
manually.
Let's improve the error message by improving the hint. Use
error_append_hint() -- which in turn requires ERRP_GUARD().
Message-ID: <20230906120503.359863-12-david@redhat.com>
Suggested-by: ThinerLogoer <logoerthiner1@163.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Tested-by: Mario Casquero <mcasquer@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
It's easy to miss that memory-backend-file with "share=off" (default)
will always try opening the file R/W as default, and fail if we don't
have write permissions to the file.
In that case, the user has to explicit specify "readonly=on,rom=off" to
get usable RAM, for example, for VM templating.
Let's hint that '-object memory-backend-file,readonly=on,rom=off,...'
exists to consume R/O files in a private mapping to create writable RAM,
but only if we have permissions to open the file read-only.
Message-ID: <20230906120503.359863-11-david@redhat.com>
Suggested-by: ThinerLogoer <logoerthiner1@163.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
Let's add some details about VM templating, focusing on the VM memory
configuration only.
There is much more to VM templating (VM state? block devices?), but I leave
that as future work.
Message-ID: <20230906120503.359863-10-david@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: David Hildenbrand <david@redhat.com>
"-mem-path" corresponds to "memory-backend-file,share=off" and,
therefore, creates a private COW mapping of the file. For multi-proces
QEMU, we need proper shared file-backed memory.
Let's make that clearer.
Message-ID: <20230906120503.359863-9-david@redhat.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
open() does not fail on directories when opening them readonly (O_RDONLY).
Currently, we succeed opening such directories and fail later during
mmap(), resulting in a misleading error message.
$ ./qemu-system-x86_64 \
-object memory-backend-file,id=ram0,mem-path=tmp,readonly=true,size=1g
qemu-system-x86_64: unable to map backing store for guest RAM: No such device
To identify directories and handle them accordingly in file_ram_open()
also when readonly=true was specified, detect if we just opened a directory
using fstat() instead. Then, fail file_ram_open() right away, similarly
to how we now fail if the file does not exist and we want to open the
file readonly.
With this change, we get a nicer error message:
qemu-system-x86_64: can't open backing store tmp for guest RAM: Is a directory
Note that the only memory-backend-file will end up calling
memory_region_init_ram_from_file() -> qemu_ram_alloc_from_file() ->
file_ram_open().
Message-ID: <20230906120503.359863-8-david@redhat.com>
Reported-by: Thiner Logoer <logoerthiner1@163.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Tested-by: Mario Casquero <mcasquer@redhat.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
Currently, if a file does not exist yet, file_ram_open() will create new
empty file and open it writable. However, it even does that when
readonly=true was specified.
Specifying O_RDONLY instead to create a new readonly file would
theoretically work, however, ftruncate() will refuse to resize the new
empty file and we'll get a warning:
ftruncate: Invalid argument
And later eventually more problems when actually mmap'ing that file and
accessing it.
If someone intends to let QEMU open+mmap a file read-only, better
create+resize+fill that file ahead of time outside of QEMU context.
We'll now fail with:
./qemu-system-x86_64 \
-object memory-backend-file,id=ram0,mem-path=tmp,readonly=true,size=1g
qemu-system-x86_64: can't open backing store tmp for guest RAM: No such file or directory
All use cases of readonly files (R/O NVDIMMs, VM templating) work on
existing files, so silently creating new files might just hide user
errors when accidentally specifying a non-existent file.
Note that the only memory-backend-file will end up calling
memory_region_init_ram_from_file() -> qemu_ram_alloc_from_file() ->
file_ram_open().
Move error reporting to the single caller.
Message-ID: <20230906120503.359863-7-david@redhat.com>
Acked-by: Peter Xu <peterx@redhat.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
For now, "share=off,readonly=on" would always result in us opening the
file R/O and mmap'ing the opened file MAP_PRIVATE R/O -- effectively
turning it into ROM.
Especially for VM templating, "share=off" is a common use case. However,
that use case is impossible with files that lack write permissions,
because "share=off,readonly=on" will not give us writable RAM.
The sole user of ROM via memory-backend-file are R/O NVDIMMs, but as we
have users (Kata Containers) that rely on the existing behavior --
malicious VMs should not be able to consume COW memory for R/O NVDIMMs --
we cannot change the semantics of "share=off,readonly=on"
So let's add a new "rom" property with on/off/auto values. "auto" is
the default and what most people will use: for historical reasons, to not
change the old semantics, it defaults to the value of the "readonly"
property.
For VM templating, one can now use:
-object memory-backend-file,share=off,readonly=on,rom=off,...
But we'll disallow:
-object memory-backend-file,share=on,readonly=on,rom=off,...
because we would otherwise get an error when trying to mmap the R/O file
shared and writable. An explicit error message is cleaner.
We will also disallow for now:
-object memory-backend-file,share=off,readonly=off,rom=on,...
-object memory-backend-file,share=on,readonly=off,rom=on,...
It's not harmful, but also not really required for now.
Alternatives that were abandoned:
* Make "unarmed=on" for the NVDIMM set the memory region container
readonly. We would still see a change of ROM->RAM and possibly run
into memslot limits with vhost-user. Further, there might be use cases
for "unarmed=on" that should still allow writing to that memory
(temporary files, system RAM, ...).
* Add a new "readonly=on/off/auto" parameter for NVDIMMs. Similar issues
as with "unarmed=on".
* Make "readonly" consume "on/off/file" instead of being a 'bool' type.
This would slightly changes the behavior of the "readonly" parameter:
values like true/false (as accepted by a 'bool'type) would no longer be
accepted.
Message-ID: <20230906120503.359863-4-david@redhat.com>
Acked-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
There is a difference between how we open a file and how we mmap it,
and we want to support writable private mappings of readonly files. Let's
define RAM_READONLY and RAM_READONLY_FD flags, to replace the single
"readonly" parameter for file-related functions.
In memory_region_init_ram_from_fd() and memory_region_init_ram_from_file(),
initialize mr->readonly based on the new RAM_READONLY flag.
While at it, add some RAM_* flags we missed to add to the list of accepted
flags in the documentation of some functions.
No change in functionality intended. We'll make use of both flags next
and start setting them independently for memory-backend-file.
Message-ID: <20230906120503.359863-3-david@redhat.com>
Acked-by: Peter Xu <peterx@redhat.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
Currently, when using a true R/O NVDIMM (ROM memory backend) with a label
area, the VM can easily crash QEMU by trying to write to the label area,
because the ROM memory is mmap'ed without PROT_WRITE.
[root@vm-0 ~]# ndctl disable-region region0
disabled 1 region
[root@vm-0 ~]# ndctl zero-labels nmem0
-> QEMU segfaults
Let's remember whether we have a ROM memory backend and properly
reject the write request:
[root@vm-0 ~]# ndctl disable-region region0
disabled 1 region
[root@vm-0 ~]# ndctl zero-labels nmem0
zeroed 0 nmem
In comparison, on a system with a R/W NVDIMM:
[root@vm-0 ~]# ndctl disable-region region0
disabled 1 region
[root@vm-0 ~]# ndctl zero-labels nmem0
zeroed 1 nmem
For ACPI, just return "unsupported", like if no label exists. For spapr,
return "H_P2", similar to when no label area exists.
Could we rely on the "unarmed" property? Maybe, but it looks cleaner to
only disallow what certainly cannot work.
After all "unarmed=on" primarily means: cannot accept persistent writes. In
theory, there might be setups where devices with "unarmed=on" set could
be used to host non-persistent data (temporary files, system RAM, ...); for
example, in Linux, admins can overwrite the "readonly" setting and still
write to the device -- which will work as long as we're not using ROM.
Allowing writing label data in such configurations can make sense.
Message-ID: <20230906120503.359863-2-david@redhat.com>
Fixes: dbd730e859 ("nvdimm: check -object memory-backend-file, readonly=on option")
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
