mshv_vtl: Check per-CPU register page before mmap

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Register-page setup is optional for each CPU. If allocation or
registration fails, mshv_vtl_configure_reg_page() warns and leaves that
CPU's reg_page NULL, but initial context setup continues successfully.
Meanwhile, successful setup on another CPU sets the global
mshv_has_reg_page flag.

mshv_vtl_fault() checks this global flag before selecting the requested
CPU's register page. With mixed setup results across online CPUs, the
check passes even for a CPU with no register page, reaching
get_page(NULL) when userspace faults in that mapping.

Check the selected per-CPU register page before taking its reference and
return VM_FAULT_SIGBUS if it is absent.

Fixes: 7bfe3b8ea6 ("Drivers: hv: Introduce mshv_vtl driver")
Cc: stable@vger.kernel.org
Signed-off-by: Hardik Garg <hargar@linux.microsoft.com>
Reviewed-by: Naman Jain <namjain@linux.microsoft.com>
Signed-off-by: Wei Liu <wei.liu@kernel.org>

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Hardik Garg 2026-09-11 17:51:46 +00:00 • committed by Wei Liu

parent d5e6896960

commit 874194a8de

1 changed files with 3 additions and 0 deletions

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drivers/hv/mshv_vtl_main.c

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