@@ -37,24 +37,42 @@
void *hv_hypercall_pg;
#ifdef CONFIG_X86_64
+static u64 __hv_hyperfail(u64 control, u64 param1, u64 param2)
+{
+ return U64_MAX;
+}
+
+DEFINE_STATIC_CALL(__hv_hypercall, __hv_hyperfail);
+
u64 hv_pg_hypercall(u64 control, u64 param1, u64 param2)
{
u64 hv_status;
- if (!hv_hypercall_pg)
- return U64_MAX;
-
register u64 __r8 asm("r8") = param2;
- asm volatile (CALL_NOSPEC
+ asm volatile ("call " STATIC_CALL_TRAMP_STR(__hv_hypercall)
: "=a" (hv_status), ASM_CALL_CONSTRAINT,
"+c" (control), "+d" (param1)
- : "r" (__r8),
- THUNK_TARGET(hv_hypercall_pg)
+ : "r" (__r8)
: "cc", "memory", "r9", "r10", "r11");
return hv_status;
}
+
+typedef u64 (*hv_hypercall_f)(u64 control, u64 param1, u64 param2);
+
+static inline void hv_set_hypercall_pg(void *ptr)
+{
+ hv_hypercall_pg = ptr;
+
+ if (!ptr)
+ ptr = &__hv_hyperfail;
+ static_call_update(__hv_hypercall, (hv_hypercall_f)ptr);
+}
#else
+static inline void hv_set_hypercall_pg(void *ptr)
+{
+ hv_hypercall_pg = ptr;
+}
EXPORT_SYMBOL_GPL(hv_hypercall_pg);
#endif
@@ -349,7 +367,7 @@ static int hv_suspend(void)
* pointer is restored on resume.
*/
hv_hypercall_pg_saved = hv_hypercall_pg;
- hv_hypercall_pg = NULL;
+ hv_set_hypercall_pg(NULL);
/* Disable the hypercall page in the hypervisor */
rdmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
@@ -375,7 +393,7 @@ static void hv_resume(void)
vmalloc_to_pfn(hv_hypercall_pg_saved);
wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
- hv_hypercall_pg = hv_hypercall_pg_saved;
+ hv_set_hypercall_pg(hv_hypercall_pg_saved);
hv_hypercall_pg_saved = NULL;
/*
@@ -529,8 +547,8 @@ void __init hyperv_init(void)
if (hv_isolation_type_tdx() && !ms_hyperv.paravisor_present)
goto skip_hypercall_pg_init;
- hv_hypercall_pg = __vmalloc_node_range(PAGE_SIZE, 1, VMALLOC_START,
- VMALLOC_END, GFP_KERNEL, PAGE_KERNEL_ROX,
+ hv_hypercall_pg = __vmalloc_node_range(PAGE_SIZE, 1, MODULES_VADDR,
+ MODULES_END, GFP_KERNEL, PAGE_KERNEL_ROX,
VM_FLUSH_RESET_PERMS, NUMA_NO_NODE,
__builtin_return_address(0));
if (hv_hypercall_pg == NULL)
@@ -568,27 +586,9 @@ void __init hyperv_init(void)
wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
}
-skip_hypercall_pg_init:
- /*
- * Some versions of Hyper-V that provide IBT in guest VMs have a bug
- * in that there's no ENDBR64 instruction at the entry to the
- * hypercall page. Because hypercalls are invoked via an indirect call
- * to the hypercall page, all hypercall attempts fail when IBT is
- * enabled, and Linux panics. For such buggy versions, disable IBT.
- *
- * Fixed versions of Hyper-V always provide ENDBR64 on the hypercall
- * page, so if future Linux kernel versions enable IBT for 32-bit
- * builds, additional hypercall page hackery will be required here
- * to provide an ENDBR32.
- */
-#ifdef CONFIG_X86_KERNEL_IBT
- if (cpu_feature_enabled(X86_FEATURE_IBT) &&
- *(u32 *)hv_hypercall_pg != gen_endbr()) {
- setup_clear_cpu_cap(X86_FEATURE_IBT);
- pr_warn("Disabling IBT because of Hyper-V bug\n");
- }
-#endif
+ hv_set_hypercall_pg(hv_hypercall_pg);
+skip_hypercall_pg_init:
/*
* hyperv_init() is called before LAPIC is initialized: see
* apic_intr_mode_init() -> x86_platform.apic_post_init() and
@@ -658,7 +658,7 @@ void hyperv_cleanup(void)
* let hypercall operations fail safely rather than
* panic the kernel for using invalid hypercall page
*/
- hv_hypercall_pg = NULL;
+ hv_set_hypercall_pg(NULL);
/* Reset the hypercall page */
hypercall_msr.as_uint64 = hv_get_msr(HV_X64_MSR_HYPERCALL);
Instead of using an indirect call to the hypercall page, use a direct call instead. This avoids all CFI problems, including the one where the hypercall page doesn't have IBT on. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> --- arch/x86/hyperv/hv_init.c | 62 +++++++++++++++++++++++----------------------- 1 file changed, 31 insertions(+), 31 deletions(-)