Messages in this thread | | | Date | Thu, 28 Apr 2022 11:04:59 -0700 | Subject | Re: [PATCH v4 1/3] x86/tdx: Add TDX Guest attestation interface driver | From | Dave Hansen <> |
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On 4/28/22 10:56, Sathyanarayanan Kuppuswamy wrote: > On 4/28/22 10:45 AM, Wander Lairson Costa wrote: >> On Fri, Apr 22, 2022 at 04:34:16PM -0700, Kuppuswamy Sathyanarayanan >> wrote: >>> +static long tdx_get_tdreport(void __user *argp) >>> +{ >>> + void *report_buf = NULL, *tdreport_buf = NULL; >>> + long ret = 0, err; >>> + >>> + /* Allocate space for report data */ >>> + report_buf = kmalloc(TDX_REPORT_DATA_LEN, GFP_KERNEL); >>> + if (!report_buf) >>> + return -ENOMEM; >>> + >>> + /* >>> + * Allocate space for TDREPORT buffer (1024-byte aligned). >>> + * Full page alignment is more than enough. >>> + */ >>> + tdreport_buf = (void *)get_zeroed_page(GFP_KERNEL); >> >> Maybe we should add BUILD_BUG_ON(TDX_TDREPORT_LEN > PAGE_SIZE) > > Currently, it is a constant value < PAGE_SIZE. But I can add the > BUILD_BUG_ON check for it.
That's kinda silly. If it might ever be bigger than a page, you just do:
tdreport_buf = alloc_pages();
But, seriously, TDX_TDREPORT_LEN is part of the ABI and can't change. kmalloc() would work too since TDX_TDREPORT_LEN is a power of 2.
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