On 9/11/2026 11:21 PM, Hardik Garg wrote:
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: 7bfe3b8ea6e3 ("Drivers: hv: Introduce mshv_vtl driver") Cc: [email protected] Signed-off-by: Hardik Garg <[email protected]> --- drivers/hv/mshv_vtl_main.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/hv/mshv_vtl_main.c b/drivers/hv/mshv_vtl_main.c index fc993560a45c..3296ab5c0243 100644 --- a/drivers/hv/mshv_vtl_main.c +++ b/drivers/hv/mshv_vtl_main.c @@ -912,6 +912,9 @@ static vm_fault_t mshv_vtl_fault(struct vm_fault *vmf) return VM_FAULT_NOPAGE; }+ if (!page)+ return VM_FAULT_SIGBUS; + get_page(page); vmf->page = page;
LGTM. Thanks. Reviewed-by: Naman Jain <[email protected]> Regards, Naman
