Re: [PATCH v8] um: Enable preemption in UML

[Anton Ivanov]

On 01/04/2024 12:04, Tiwei Bie wrote:

On 3/29/24 3:50 AM, anton.iva...@cambridgegreys.com wrote:
[...]

+
+void kernel_fpu_begin(void)
+{
+       preempt_disable();
+
+       WARN_ON(this_cpu_read(in_kernel_fpu));
+
+       this_cpu_write(in_kernel_fpu, true);
+
+#ifdef CONFIG_64BIT
+       if (likely(cpu_has(&boot_cpu_data, X86_FEATURE_XSAVEOPT)))
+               __builtin_ia32_xsaveopt64(&current_thread_info()->aux_fp_regs, 
KNOWN_387_FEATURES);
+       else if (likely(cpu_has(&boot_cpu_data, X86_FEATURE_XSAVE)))
+                       
__builtin_ia32_xsave64(&current_thread_info()->aux_fp_regs, KNOWN_387_FEATURES);

Only need two levels of indentation (i.e. two tabs) here.

+       else
+               __builtin_ia32_fxsave64(&current_thread_info()->aux_fp_regs);
+#else
+       if (likely(cpu_has(&boot_cpu_data, X86_FEATURE_XSAVEOPT)))
+               __builtin_ia32_xsaveopt(&current->aux_fp_regs, 
KNOWN_387_FEATURES);
+       else if (likely(cpu_has(&boot_cpu_data, X86_FEATURE_XSAVE)))
+                       __builtin_ia32_xsave(&current->aux_fp_regs, 
KNOWN_387_FEATURES);

Ditto.

+       else
+               __builtin_ia32_fxsave(&current->aux_fp_regs);
+#endif
+}
+EXPORT_SYMBOL_GPL(kernel_fpu_begin);
+

[...]

@@ -466,6 +475,8 @@ void flush_tlb_page(struct vm_area_struct *vma, unsigned long address) address &= PAGE_MASK; + preempt_disable();

+
        pgd = pgd_offset(mm, address);
        if (!pgd_present(*pgd))
                goto kill;
@@ -520,6 +531,7 @@ void flush_tlb_page(struct vm_area_struct *vma, unsigned 
long address)

*pte = pte_mkuptodate(*pte); + preempt_enable();

        return;

kill:

Preemption isn't enabled in the error path.

Thanks - missed that.

Regards,
Tiwei

--
Anton R. Ivanov
Cambridgegreys Limited. Registered in England. Company Number 10273661
https://www.cambridgegreys.com/