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Shutemov" , LKML , x86@kernel.org, David Woodhouse , Andrew Cooper , Brian Gerst , Arjan van de Veen , Paolo Bonzini , Paul McKenney , Oleksandr Natalenko , Paul Menzel , "Guilherme G. Piccoli" , Piotr Gorski , Usama Arif , Juergen Gross , Boris Ostrovsky , xen-devel@lists.xenproject.org, Russell King , Arnd Bergmann , linux-arm-kernel@lists.infradead.org, Catalin Marinas , Will Deacon , Guo Ren , linux-csky@vger.kernel.org, Thomas Bogendoerfer , linux-mips@vger.kernel.org, "James E.J. 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Shutemov wrote: >>>> On Tue, May 30, 2023 at 02:09:17PM +0200, Thomas Gleixner wrote: >>>>> The decision to allow parallel bringup of secondary CPUs checks >>>>> CC_ATTR_GUEST_STATE_ENCRYPT to detect encrypted guests. Those cannot use >>>>> parallel bootup because accessing the local APIC is intercepted and raises >>>>> a #VC or #VE, which cannot be handled at that point. >>>>> >>>>> The check works correctly, but only for AMD encrypted guests. TDX does not >>>>> set that flag. >>>>> >>>>> Check for cc_vendor != CC_VENDOR_NONE instead. That might be overbroad, but >>>>> definitely works for both AMD and Intel. >>>> >>>> It boots fine with TDX, but I think it is wrong. cc_get_vendor() will >>>> report CC_VENDOR_AMD even on bare metal if SME is enabled. I don't think >>>> we want it. >>> >>> Right. Did not think about that. >>> >>> But the same way is CC_ATTR_GUEST_MEM_ENCRYPT overbroad for AMD. Only >>> SEV-ES traps RDMSR if I'm understandig that maze correctly. >> >> Ya, regular SEV doesn't encrypt register state. > > That aside. From a semantical POV making this decision about parallel > bootup based on some magic CC encryption attribute is questionable. > > I'm tending to just do the below and make this CC agnostic (except that > I couldn't find the right spot for SEV-ES to clear that flag.) Maybe in sme_sev_setup_real_mode() in arch/x86/realmode/init.c? You could clear the flag within the CC_ATTR_GUEST_STATE_ENCRYPT check. Thanks, Tom > > Thanks, > > tglx > --- > --- a/arch/x86/coco/tdx/tdx.c > +++ b/arch/x86/coco/tdx/tdx.c > @@ -871,5 +871,7 @@ void __init tdx_early_init(void) > x86_platform.guest.enc_tlb_flush_required = tdx_tlb_flush_required; > x86_platform.guest.enc_status_change_finish = tdx_enc_status_changed; > > + x86_cpuinit.parallel_bringup = false; > + > pr_info("Guest detected\n"); > } > --- a/arch/x86/include/asm/x86_init.h > +++ b/arch/x86/include/asm/x86_init.h > @@ -2,6 +2,7 @@ > #ifndef _ASM_X86_PLATFORM_H > #define _ASM_X86_PLATFORM_H > > +#include > #include > > struct ghcb; > @@ -177,11 +178,14 @@ struct x86_init_ops { > * struct x86_cpuinit_ops - platform specific cpu hotplug setups > * @setup_percpu_clockev: set up the per cpu clock event device > * @early_percpu_clock_init: early init of the per cpu clock event device > + * @fixup_cpu_id: fixup function for cpuinfo_x86::phys_proc_id > + * @parallel_bringup: Parallel bringup control > */ > struct x86_cpuinit_ops { > void (*setup_percpu_clockev)(void); > void (*early_percpu_clock_init)(void); > void (*fixup_cpu_id)(struct cpuinfo_x86 *c, int node); > + bool parallel_bringup; > }; > > struct timespec64; > --- a/arch/x86/kernel/smpboot.c > +++ b/arch/x86/kernel/smpboot.c > @@ -1287,6 +1287,11 @@ bool __init arch_cpuhp_init_parallel_bri > return false; > } > > + if (!x86_cpuinit.parallel_bringup) { > + pr_info("Parallel CPU startup disabled by the platform\n"); > + return false; > + } > + > smpboot_control = STARTUP_READ_APICID; > pr_debug("Parallel CPU startup enabled: 0x%08x\n", smpboot_control); > return true; > --- a/arch/x86/kernel/x86_init.c > +++ b/arch/x86/kernel/x86_init.c > @@ -126,6 +126,7 @@ struct x86_init_ops x86_init __initdata > struct x86_cpuinit_ops x86_cpuinit = { > .early_percpu_clock_init = x86_init_noop, > .setup_percpu_clockev = setup_secondary_APIC_clock, > + .parallel_bringup = true, > }; > > static void default_nmi_init(void) { };