Messages in this thread | | | Subject | Re: [PATCH v5 5/5] x86/kvm: Avoid dynamic allocation of pvclock data when SEV is active | From | Brijesh Singh <> | Date | Thu, 6 Sep 2018 15:20:46 -0500 |
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On 09/06/2018 02:47 PM, Sean Christopherson wrote: ...
>> >> Yes, the auxiliary array will dumped into the regular .bss when >> CONFIG_AMD_MEM_ENCRYPT=n. Typically it will be few k, I am not >> sure if its worth complicating the code to save those extra memory. >> Most of the distro's have CONFIG_AMD_MEM_ENCRYPT=y anyways. > > I just realized that we'll try to create a bogus array if 'NR_CPUS <= > HVC_BOOT_ARRAY_SIZE'. A bit ugly, but we could #ifdef away both that > and CONFIG_AMD_MEM_ENCRYPT=n in a single shot, e.g.: > > #if defined(CONFIG_AMD_MEM_ENCRYPT) && NR_CPUS > HVC_BOOT_ARRAY_SIZE > #define HVC_AUX_ARRAY_SIZE \ > PAGE_ALIGN((NR_CPUS - HVC_BOOT_ARRAY_SIZE) * \ > sizeof(struct pvclock_vsyscall_time_info)) > static struct pvclock_vsyscall_time_info > hv_clock_aux[HVC_AUX_ARRAY_SIZE] __decrypted __aligned(PAGE_SIZE); > #endif >
The HVC_BOOT_ARRAY_SIZE macro uses sizeof(..) and to my understanding the sizeof operators are not allowed in '#if'. Anyway, I will try to see if it can be used, if not then I will stick to CONFIG_AMD_MEM_ENCRYPT check.
-Brijesh
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