diff options
| author | Vitaly Kuznetsov <vkuznets@redhat.com> | 2021-10-06 15:50:16 +0300 |
|---|---|---|
| committer | Wei Liu <wei.liu@kernel.org> | 2021-10-06 18:56:45 +0300 |
| commit | f5c20e4a5f18677e22d8dd2846066251b006a62d (patch) | |
| tree | 5b01533cb990142e691163da364cb5a50e26b3d9 | |
| parent | 95a13ee858c9e426e63c97063677736f74af7163 (diff) | |
| download | linux-f5c20e4a5f18677e22d8dd2846066251b006a62d.tar.xz | |
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: Thomas Gleixner <tglx@linutronix.de>
Fixes: dfb5c1e12c28 ("x86/hyperv: remove on-stack cpumask from hv_send_ipi_mask_allbutself")
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
Link: https://lore.kernel.org/r/20211006125016.941616-1-vkuznets@redhat.com
Signed-off-by: Wei Liu <wei.liu@kernel.org>
| -rw-r--r-- | arch/x86/hyperv/hv_apic.c | 20 |
1 files changed, 15 insertions, 5 deletions
diff --git a/arch/x86/hyperv/hv_apic.c b/arch/x86/hyperv/hv_apic.c index 32a1ad356c18..db2d92fb44da 100644 --- a/arch/x86/hyperv/hv_apic.c +++ b/arch/x86/hyperv/hv_apic.c @@ -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) - goto ipi_mask_ex_done; - if (!nr_bank) + + /* + * '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; + } 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); |