diff options
| author | Michael Kelley <mhklinux@outlook.com> | 2025-12-31 12:14:47 -0800 |
|---|---|---|
| committer | Wei Liu <wei.liu@kernel.org> | 2026-01-15 07:01:33 +0000 |
| commit | 49f49d47af67f8a7b221db1d758fc634242dc91a (patch) | |
| tree | 629789fc87529ab7ccc2485cde59e8142867fb4d /drivers/hv | |
| parent | fc558188f251f5df6dd11ac409d668733d9baac7 (diff) | |
Drivers: hv: Always do Hyper-V panic notification in hv_kmsg_dump()
hv_kmsg_dump() currently skips the panic notification entirely if it
doesn't get any message bytes to pass to Hyper-V due to an error from
kmsg_dump_get_buffer(). Skipping the notification is undesirable because
it leaves the Hyper-V host uncertain about the state of a panic'ed guest.
Fix this by always doing the panic notification, even if bytes_written
is zero. Also ensure that bytes_written is initialized, which fixes a
kernel test robot warning. The warning is actually bogus because
kmsg_dump_get_buffer() happens to set bytes_written even if it fails, and
in the kernel test robot's CONFIG_PRINTK not set case, hv_kmsg_dump() is
never called. But do the initialization for robustness and to quiet the
static checker.
Fixes: 9c318a1d9b50 ("Drivers: hv: move panic report code from vmbus to hv early init code")
Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Closes: https://lore.kernel.org/all/202512172103.OcUspn1Z-lkp@intel.com/
Signed-off-by: Michael Kelley <mhklinux@outlook.com>
Reviewed-by: Roman Kisel <vdso@mailbox.org>
Signed-off-by: Wei Liu <wei.liu@kernel.org>
Diffstat (limited to 'drivers/hv')
| -rw-r--r-- | drivers/hv/hv_common.c | 12 |
1 files changed, 7 insertions, 5 deletions
diff --git a/drivers/hv/hv_common.c b/drivers/hv/hv_common.c index 0a3ab7efed46..f1c17fb60dc1 100644 --- a/drivers/hv/hv_common.c +++ b/drivers/hv/hv_common.c @@ -195,13 +195,15 @@ static void hv_kmsg_dump(struct kmsg_dumper *dumper, /* * Write dump contents to the page. No need to synchronize; panic should - * be single-threaded. + * be single-threaded. Ignore failures from kmsg_dump_get_buffer() since + * panic notification should be done even if there is no message data. + * Don't assume bytes_written is set in case of failure, so initialize it. */ kmsg_dump_rewind(&iter); - kmsg_dump_get_buffer(&iter, false, hv_panic_page, HV_HYP_PAGE_SIZE, + bytes_written = 0; + (void)kmsg_dump_get_buffer(&iter, false, hv_panic_page, HV_HYP_PAGE_SIZE, &bytes_written); - if (!bytes_written) - return; + /* * P3 to contain the physical address of the panic page & P4 to * contain the size of the panic data in that page. Rest of the @@ -210,7 +212,7 @@ static void hv_kmsg_dump(struct kmsg_dumper *dumper, hv_set_msr(HV_MSR_CRASH_P0, 0); hv_set_msr(HV_MSR_CRASH_P1, 0); hv_set_msr(HV_MSR_CRASH_P2, 0); - hv_set_msr(HV_MSR_CRASH_P3, virt_to_phys(hv_panic_page)); + hv_set_msr(HV_MSR_CRASH_P3, bytes_written ? virt_to_phys(hv_panic_page) : 0); hv_set_msr(HV_MSR_CRASH_P4, bytes_written); /* |