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authorVitaly Kuznetsov <vkuznets@redhat.com>2021-10-06 14:50:16 +0200
committerWei Liu <wei.liu@kernel.org>2021-10-06 15:56:45 +0000
commitf5c20e4a5f18677e22d8dd2846066251b006a62d (patch)
tree5b01533cb990142e691163da364cb5a50e26b3d9 /arch
parent95a13ee858c9e426e63c97063677736f74af7163 (diff)
downloadlinux-f5c20e4a5f18677e22d8dd2846066251b006a62d.tar.gz
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>
Diffstat (limited to 'arch')
-rw-r--r--arch/x86/hyperv/hv_apic.c20
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);