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Diffstat (limited to 'arch/x86/hyperv/hv_init.c')
-rw-r--r--arch/x86/hyperv/hv_init.c13
1 files changed, 11 insertions, 2 deletions
diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c
index 0e033ef11a9f..0d258688c8cf 100644
--- a/arch/x86/hyperv/hv_init.c
+++ b/arch/x86/hyperv/hv_init.c
@@ -60,8 +60,17 @@ static int hv_cpu_init(unsigned int cpu)
if (!hv_vp_assist_page)
return 0;
- if (!*hvp)
- *hvp = __vmalloc(PAGE_SIZE, GFP_KERNEL, PAGE_KERNEL);
+ /*
+ * The VP ASSIST PAGE is an "overlay" page (see Hyper-V TLFS's Section
+ * 5.2.1 "GPA Overlay Pages"). Here it must be zeroed out to make sure
+ * we always write the EOI MSR in hv_apic_eoi_write() *after* the
+ * EOI optimization is disabled in hv_cpu_die(), otherwise a CPU may
+ * not be stopped in the case of CPU offlining and the VM will hang.
+ */
+ if (!*hvp) {
+ *hvp = __vmalloc(PAGE_SIZE, GFP_KERNEL | __GFP_ZERO,
+ PAGE_KERNEL);
+ }
if (*hvp) {
u64 val;