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Message-ID: <69b46bf3-40ab-c379-03d5-efd537ed44c7@intel.com>
Date: Fri, 11 Aug 2023 07:09:40 -0700
From: Dave Hansen <dave.hansen@...el.com>
To: Dexuan Cui <decui@...rosoft.com>, x86@...nel.org,
ak@...ux.intel.com, arnd@...db.de, bp@...en8.de,
brijesh.singh@....com, dan.j.williams@...el.com,
dave.hansen@...ux.intel.com, haiyangz@...rosoft.com, hpa@...or.com,
jane.chu@...cle.com, kirill.shutemov@...ux.intel.com,
kys@...rosoft.com, luto@...nel.org, mingo@...hat.com,
peterz@...radead.org, rostedt@...dmis.org,
sathyanarayanan.kuppuswamy@...ux.intel.com, seanjc@...gle.com,
tglx@...utronix.de, tony.luck@...el.com, wei.liu@...nel.org,
Jason@...c4.com, nik.borisov@...e.com, mikelley@...rosoft.com
Cc: linux-hyperv@...r.kernel.org, linux-kernel@...r.kernel.org,
Tianyu.Lan@...rosoft.com, rick.p.edgecombe@...el.com,
andavis@...hat.com, mheslin@...hat.com, vkuznets@...hat.com,
xiaoyao.li@...el.com
Subject: Re: [PATCH RESEND v9 2/2] x86/tdx: Support vmalloc() for
tdx_enc_status_changed()
On 8/10/23 19:12, Dexuan Cui wrote:
> + if (!is_vmalloc_addr((void *)start))
> + return tdx_enc_status_changed_phys(__pa(start), __pa(end), enc);
> +
> + while (start < end) {
> + phys_addr_t start_pa = slow_virt_to_phys((void *)start);
> + phys_addr_t end_pa = start_pa + PAGE_SIZE;
> +
> + if (!tdx_enc_status_changed_phys(start_pa, end_pa, enc))
> + return false;
> +
> + start += PAGE_SIZE;
> + }
This creates two different paths for vmalloc() and the direct map.
There are two different ways to do va=>pa conversion, for instance.
Here's a single loop that works for both cases:
unsigned long step = end - start;
unsigned long addr;
/* Step through page-by-page for vmalloc() mappings: */
if (is_vmalloc_addr((void *)vaddr))
step = PAGE_SIZE;
for (addr = start; addr < end; addr += step) {
phys_addr_t start_pa = slow_virt_to_phys(addr);
phys_addr_t end_pa = start_pa + step;
if (!tdx_enc_status_changed_phys(start_pa, end_pa, enc))
return false;
}
Note that this also doesn't abuse 'start' by making it a loop variable.
It also, uh, uses a for() loop.
The only downside is that it costs a page table walk for direct map
virt=>phys conversion. I can live with that.
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