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Fri, 31 Oct 2025 18:32:55 +0000 Message-ID: <1f3070d5-17df-4fc8-9700-bb8e37a3b0a1@intel.com> Date: Fri, 31 Oct 2025 11:32:50 -0700 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v11 5/9] x86/efi: Disable LASS while mapping the EFI runtime services Content-Language: en-US To: Dave Hansen , , Dave Hansen , Thomas Gleixner , "Ingo Molnar" , Borislav Petkov CC: Jonathan Corbet , "H . 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Why are preemption and interrupts not a problem? > This is called pretty early on from the BSP init flow. start_kernel() arch_cpu_finalize_init() efi_enter_virtual_mode() __efi_enter_virtual_mode() I had assumed we run with interrupts disabled. But, that's not true. Interrupts are enabled midway during start_kernel(). So, arch_cpu_finalize_init() is called with interrupts enabled. We write to CR bits during FPU init which happens right before EFI enters virtual mode. So I am probably missing something obvious that makes it okay.