Commit f5c20e4a authored by Vitaly Kuznetsov's avatar Vitaly Kuznetsov Committed by Wei Liu
Browse files

x86/hyperv: Avoid erroneously sending IPI to 'self' 



__send_ipi_mask_ex() uses an optimization: when the target CPU mask is
equal to 'cpu_present_mask' it uses 'HV_GENERIC_SET_ALL' format to avoid
converting the specified cpumask to VP_SET. This case was overlooked when
'exclude_self' parameter was added. As the result, a spurious IPI to
'self' can be send.

Reported-by: default avatarThomas Gleixner <tglx@linutronix.de>
Fixes: dfb5c1e1 ("x86/hyperv: remove on-stack cpumask from hv_send_ipi_mask_allbutself")
Signed-off-by: default avatarVitaly Kuznetsov <vkuznets@redhat.com>
Reviewed-by: default avatarMichael Kelley <mikelley@microsoft.com>
Link: https://lore.kernel.org/r/20211006125016.941616-1-vkuznets@redhat.com


Signed-off-by: default avatarWei Liu <wei.liu@kernel.org>
parent 95a13ee8

arch/x86/hyperv/hv_apic.c

+15 −5
Original line number Diff line number Diff line
@@ -122,17 +122,27 @@ static bool __send_ipi_mask_ex(const struct cpumask *mask, int vector, 
	ipi_arg->reserved = 0;

	ipi_arg->vp_set.valid_bank_mask = 0;



	if (!cpumask_equal(mask, cpu_present_mask)) {

	/*

	 * Use HV_GENERIC_SET_ALL and avoid converting cpumask to VP_SET

	 * when the IPI is sent to all currently present CPUs.

	 */

	if (!cpumask_equal(mask, cpu_present_mask) || exclude_self) {

		ipi_arg->vp_set.format = HV_GENERIC_SET_SPARSE_4K;

		if (exclude_self)

			nr_bank = cpumask_to_vpset_noself(&(ipi_arg->vp_set), mask);

		else

			nr_bank = cpumask_to_vpset(&(ipi_arg->vp_set), mask);

	}

	if (nr_bank < 0)



		/*

		 * 'nr_bank <= 0' means some CPUs in cpumask can't be

		 * represented in VP_SET. Return an error and fall back to

		 * native (architectural) method of sending IPIs.

		 */

		if (nr_bank <= 0)

			goto ipi_mask_ex_done;

	if (!nr_bank)

	} else {

		ipi_arg->vp_set.format = HV_GENERIC_SET_ALL;

	}



	status = hv_do_rep_hypercall(HVCALL_SEND_IPI_EX, 0, nr_bank,

			      ipi_arg, NULL);