Make setup_vmcs_config() preemption disabled so it always performs on
the same local cpu.
During module loading time, KVM intends to call setup_vmcs_config() to
set up the global VMCS configurations on _one_ cpu in hardware_setup(),
and then calls setup_vmcs_config() on all other online cpus via sending
IPI to perform VMX compatibility check. Further more, KVM has CPU
hotplug callback to call setup_vmcs_config() to do compatibility check
on the "new-online" cpu to make sure it is compatible too.
setup_vmcs_config() is supposed to be done on the same cpu. This is
true in the compatibility check code path as setup_vmcs_config() is
called either via IPI or in per-cpu CPU hotplug thread. However, the
first call from hardware_setup() isn't as it is called when preemption
is enabled.
Change the existing setup_vmcs_config() to __setup_vmcs_config() and
call the latter directly in the compatibility check code path. Change
setup_vmcs_config() to call __setup_vmcs_config() with preemption
disabled so __setup_vmcs_config() is always done on the same cpu.
Signed-off-by: Kai Huang <kai.huang@xxxxxxxxx>
---
arch/x86/kvm/vmx/vmx.c | 18 +++++++++++++++---
1 file changed, 15 insertions(+), 3 deletions(-)
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 33614ee2cd67..dfbc0e9095ec 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -2578,8 +2578,8 @@ static u64 adjust_vmx_controls64(u64 ctl_opt, u32 msr)
return ctl_opt & allowed;
}
-static int setup_vmcs_config(struct vmcs_config *vmcs_conf,
- struct vmx_capability *vmx_cap)
+static int __setup_vmcs_config(struct vmcs_config *vmcs_conf,
+ struct vmx_capability *vmx_cap)
{
u32 vmx_msr_low, vmx_msr_high;
u32 _pin_based_exec_control = 0;
@@ -2745,6 +2745,18 @@ static int setup_vmcs_config(struct vmcs_config *vmcs_conf,
return 0;
}
+static int setup_vmcs_config(struct vmcs_config *vmcs_conf,
+ struct vmx_capability *vmx_cap)
+{
+ int ret;
+
+ preempt_disable();
+ ret = __setup_vmcs_config(vmcs_conf, vmx_cap);
+ preempt_enable();
+
+ return ret;
+}
+
static bool kvm_is_vmx_supported(void)
{
int cpu = raw_smp_processor_id();
@@ -2772,7 +2784,7 @@ static int vmx_check_processor_compat(void)
if (!kvm_is_vmx_supported())
return -EIO;
- if (setup_vmcs_config(&vmcs_conf, &vmx_cap) < 0) {
+ if (__setup_vmcs_config(&vmcs_conf, &vmx_cap) < 0) {
pr_err("Failed to setup VMCS config on CPU %d\n", cpu);
return -EIO;
}
base-commit: 93827a0a36396f2fd6368a54a020f420c8916e9b
--
2.39.1
