Pointers to ring-buffer packets sent by Hyper-V are used within the
guest VM. Hyper-V can send packets with erroneous values or modify
packet fields after they are processed by the guest. To defend
against these scenarios, return a copy of the incoming VMBus packet
after validating its length and offset fields in hv_pkt_iter_first().
In this way, the packet can no longer be modified by the host.
Signed-off-by: Andres Beltran <lkmlabelt@gmail.com>
Co-developed-by: Andrea Parri (Microsoft) <parri.andrea@gmail.com>
Signed-off-by: Andrea Parri (Microsoft) <parri.andrea@gmail.com>
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
Link: https://lore.kernel.org/r/20210408161439.341988-1-parri.andrea@gmail.com
Signed-off-by: Wei Liu <wei.liu@kernel.org>
Pull printk updates from Petr Mladek:
- Stop synchronizing kernel log buffer readers by logbuf_lock. As a
result, the access to the buffer is fully lockless now.
Note that printk() itself still uses locks because it tries to flush
the messages to the console immediately. Also the per-CPU temporary
buffers are still there because they prevent infinite recursion and
serialize backtraces from NMI. All this is going to change in the
future.
- kmsg_dump API rework and cleanup as a side effect of the logbuf_lock
removal.
- Make bstr_printf() aware that %pf and %pF formats could deference the
given pointer.
- Show also page flags by %pGp format.
- Clarify the documentation for plain pointer printing.
- Do not show no_hash_pointers warning multiple times.
- Update Senozhatsky email address.
- Some clean up.
* tag 'printk-for-5.13' of git://git.kernel.org/pub/scm/linux/kernel/git/printk/linux: (24 commits)
lib/vsprintf.c: remove leftover 'f' and 'F' cases from bstr_printf()
printk: clarify the documentation for plain pointer printing
kernel/printk.c: Fixed mundane typos
printk: rename vprintk_func to vprintk
vsprintf: dump full information of page flags in pGp
mm, slub: don't combine pr_err with INFO
mm, slub: use pGp to print page flags
MAINTAINERS: update Senozhatsky email address
lib/vsprintf: do not show no_hash_pointers message multiple times
printk: console: remove unnecessary safe buffer usage
printk: kmsg_dump: remove _nolock() variants
printk: remove logbuf_lock
printk: introduce a kmsg_dump iterator
printk: kmsg_dumper: remove @active field
printk: add syslog_lock
printk: use atomic64_t for devkmsg_user.seq
printk: use seqcount_latch for clear_seq
printk: introduce CONSOLE_LOG_MAX
printk: consolidate kmsg_dump_get_buffer/syslog_print_all code
printk: refactor kmsg_dump_get_buffer()
...
There is not a consistent pattern for checking Hyper-V hypercall status.
Existing code uses a number of variants. The variants work, but a consistent
pattern would improve the readability of the code, and be more conformant
to what the Hyper-V TLFS says about hypercall status.
Implemented new helper functions hv_result(), hv_result_success(), and
hv_repcomp(). Changed the places where hv_do_hypercall() and related variants
are used to use the helper functions.
Signed-off-by: Joseph Salisbury <joseph.salisbury@microsoft.com>
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
Link: https://lore.kernel.org/r/1618620183-9967-2-git-send-email-joseph.salisbury@linux.microsoft.com
Signed-off-by: Wei Liu <wei.liu@kernel.org>
When running in Azure, disks may be connected to a Linux VM with
read/write caching enabled. If a VM panics and issues a VMbus
UNLOAD request to Hyper-V, the response is delayed until all dirty
data in the disk cache is flushed. In extreme cases, this flushing
can take 10's of seconds, depending on the disk speed and the amount
of dirty data. If kdump is configured for the VM, the current 10 second
timeout in vmbus_wait_for_unload() may be exceeded, and the UNLOAD
complete message may arrive well after the kdump kernel is already
running, causing problems. Note that no problem occurs if kdump is
not enabled because Hyper-V waits for the cache flush before doing
a reboot through the BIOS/UEFI code.
Fix this problem by increasing the timeout in vmbus_wait_for_unload()
to 100 seconds. Also output periodic messages so that if anyone is
watching the serial console, they won't think the VM is completely
hung.
Fixes: 911e1987ef ("Drivers: hv: vmbus: Add timeout to vmbus_wait_for_unload")
Signed-off-by: Michael Kelley <mikelley@microsoft.com>
Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Link: https://lore.kernel.org/r/1618894089-126662-1-git-send-email-mikelley@microsoft.com
Signed-off-by: Wei Liu <wei.liu@kernel.org>
The "open_info" variable is added to the &vmbus_connection.chn_msg_list,
but the error handling frees "open_info" without removing it from the
list. This will result in a use after free. First remove it from the
list, and then free it.
Fixes: 6f3d791f30 ("Drivers: hv: vmbus: Fix rescind handling issues")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Andrea Parri <parri.andrea@gmail.com>
Link: https://lore.kernel.org/r/YHV3XLCot6xBS44r@mwanda
Signed-off-by: Wei Liu <wei.liu@kernel.org>
Running out of request IDs on a channel essentially produces the same
effect as running out of space in the ring buffer, in that -EAGAIN is
returned. The error message in hv_ringbuffer_write() should either be
dropped (since we don't output a message when the ring buffer is full)
or be made conditional/debug-only.
Suggested-by: Michael Kelley <mikelley@microsoft.com>
Signed-off-by: Andrea Parri (Microsoft) <parri.andrea@gmail.com>
Fixes: e8b7db3844 ("Drivers: hv: vmbus: Add vmbus_requestor data structure for VMBus hardening")
Link: https://lore.kernel.org/r/20210301191348.196485-1-parri.andrea@gmail.com
Signed-off-by: Wei Liu <wei.liu@kernel.org>
VMbus interrupts are most naturally modelled as per-cpu IRQs. But
because x86/x64 doesn't have per-cpu IRQs, the core VMbus interrupt
handling machinery is done in code under arch/x86 and Linux IRQs are
not used. Adding support for ARM64 means adding equivalent code
using per-cpu IRQs under arch/arm64.
A better model is to treat per-cpu IRQs as the normal path (which it is
for modern architectures), and the x86/x64 path as the exception. Do this
by incorporating standard Linux per-cpu IRQ allocation into the main VMbus
driver, and bypassing it in the x86/x64 exception case. For x86/x64,
special case code is retained under arch/x86, but no VMbus interrupt
handling code is needed under arch/arm64.
No functional change.
Signed-off-by: Michael Kelley <mikelley@microsoft.com>
Reviewed-by: Boqun Feng <boqun.feng@gmail.com>
Link: https://lore.kernel.org/r/1614721102-2241-7-git-send-email-mikelley@microsoft.com
Signed-off-by: Wei Liu <wei.liu@kernel.org>
Current code defines a separate get and set macro for each Hyper-V
synthetic MSR used by the VMbus driver. Furthermore, the get macro
can't be converted to a standard function because the second argument
is modified in place, which is somewhat bad form.
Redo this by providing a single get and a single set function that
take a parameter specifying the MSR to be operated on. Fixup usage
of the get function. Calling locations are no more complex than before,
but the code under arch/x86 and the upcoming code under arch/arm64
is significantly simplified.
Also standardize the names of Hyper-V synthetic MSRs that are
architecture neutral. But keep the old x86-specific names as aliases
that can be removed later when all references (particularly in KVM
code) have been cleaned up in a separate patch series.
No functional change.
Signed-off-by: Michael Kelley <mikelley@microsoft.com>
Reviewed-by: Boqun Feng <boqun.feng@gmail.com>
Link: https://lore.kernel.org/r/1614721102-2241-4-git-send-email-mikelley@microsoft.com
Signed-off-by: Wei Liu <wei.liu@kernel.org>
Rather than storing the iterator information in the registered
kmsg_dumper structure, create a separate iterator structure. The
kmsg_dump_iter structure can reside on the stack of the caller, thus
allowing lockless use of the kmsg_dump functions.
Update code that accesses the kernel logs using the kmsg_dumper
structure to use the new kmsg_dump_iter structure. For kmsg_dumpers,
this also means adding a call to kmsg_dump_rewind() to initialize
the iterator.
All this is in preparation for removal of @logbuf_lock.
Signed-off-by: John Ogness <john.ogness@linutronix.de>
Reviewed-by: Kees Cook <keescook@chromium.org> # pstore
Reviewed-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20210303101528.29901-13-john.ogness@linutronix.de
