On 9/23/2021 4:52 PM, Thomas Gleixner wrote:
On Mon, Sep 13 2021 at 13:01, Sohil Mehta wrote:
+/* UPID Notification control status */ +#define UPID_ON 0x0 /* Outstanding notification */ +#define UPID_SN 0x1 /* Suppressed notification */ Come on. This are bits in upid.status, right? So why can't the comment above these defines says so and why can't the names not reflect that?
I'll fix this.
+struct uintr_upid_ctx {
- struct uintr_upid *upid;
- refcount_t refs;
Please use tabular format for struct members.
Will do.
+};
+struct uintr_receiver {
- struct uintr_upid_ctx *upid_ctx;
+};
So we need a struct to wrap a pointer to another struct. Why?
The struct will have more members added later. Should the wrapper be created then?
I didn't want to add members that are not used in this patch.
+inline bool uintr_arch_enabled(void)
What's this arch_enabled indirection for? Is this used anywhere in non-architecture code?
I'll remove this indirection.
It is a remnant of some older code that had uintr_fd managed outside of the x86 code.
+{
- return static_cpu_has(X86_FEATURE_UINTR);
+}
+static inline bool is_uintr_receiver(struct task_struct *t) +{
- return !!t->thread.ui_recv;
+}
+static inline u32 cpu_to_ndst(int cpu) +{
- u32 apicid = (u32)apic->cpu_present_to_apicid(cpu);
- WARN_ON_ONCE(apicid == BAD_APICID);
Brilliant. If x2apic is not enabled then this case returns
I'll fix this.
- if (!x2apic_enabled())
return (apicid << 8) & 0xFF00;(BAD_APICID << 8) & 0xFF00 == 0xFF ....
+int do_uintr_unregister_handler(void) +{
- struct task_struct *t = current;
- struct fpu *fpu = &t->thread.fpu;
- struct uintr_receiver *ui_recv;
- u64 msr64;
- if (!is_uintr_receiver(t))
return -EINVAL;- pr_debug("recv: Unregister handler and clear MSRs for task=%d\n",
t->pid);- /*
* TODO: Evaluate usage of fpregs_lock() and get_xsave_addr(). Bugs* have been reported recently for PASID and WRPKRU.Again. Which bugs and why haven't they been evaluated before posting?
I apologize again. This comment is no longer valid.
* UPID and ui_recv will be referenced during context switch. Need to* disable preemption while modifying the MSRs, UPID and ui_recv thread* struct.*/- fpregs_lock();
And because you need to disable preemption you need to use fpregs_lock(), right? That's not what fpregs_lock() is about.
Got it. I'll evaluate the use of fpregs_lock() at all places.
wrmsrl(MSR_IA32_UINTR_MISC, msr64);wrmsrl(MSR_IA32_UINTR_PD, 0ULL);wrmsrl(MSR_IA32_UINTR_RR, 0ULL);wrmsrl(MSR_IA32_UINTR_STACKADJUST, 0ULL);wrmsrl(MSR_IA32_UINTR_HANDLER, 0ULL);- } else {
struct uintr_state *p;p = get_xsave_addr(&fpu->state.xsave, XFEATURE_UINTR);if (p) {p->handler = 0;p->stack_adjust = 0;p->upid_addr = 0;p->uinv = 0;p->uirr = 0;}So p == NULL is expected here?
I'll fix this and other usages of get_xsave_addr().
Thanks,
Sohil