lkml.org 
[lkml]   [2017]   [Dec]   [4]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH] x86/mm: Rewrite sme_populate_pgd() in a more sensible way
From
Date
On 12/4/2017 5:23 AM, Kirill A. Shutemov wrote:
> sme_populate_pgd() open-codes a lot of things that are not needed to be
> open-coded.
>
> Let's rewrite it in a more stream-lined way.
>
> This would also buy us boot-time switching between support between
> paging modes, when rest of the pieces will be upstream.

Hi Kirill,

Unfortunately, some of these can't be changed. The use of p4d_offset(),
pud_offset(), etc., use non-identity mapped virtual addresses which cause
failures at this point of the boot process. Also, calls such as __p4d(),
__pud(), etc., are part of the paravirt support and can't be used yet,
either. I can take a closer look at some of the others (p*d_none() and
p*d_large()) which make use of the native_ macros, but my worry would be
that these get changed in the future to the non-native calls and then
boot failures occur.

Thanks,
Tom

>
> Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
> ---
>
> The patch is only build tested. I don't have hardware. Tom, could you give it a try?
>
> ---
> arch/x86/mm/mem_encrypt.c | 89 +++++++++++++++--------------------------------
> 1 file changed, 29 insertions(+), 60 deletions(-)
>
> diff --git a/arch/x86/mm/mem_encrypt.c b/arch/x86/mm/mem_encrypt.c
> index d9a9e9fc75dd..16038f7472ca 100644
> --- a/arch/x86/mm/mem_encrypt.c
> +++ b/arch/x86/mm/mem_encrypt.c
> @@ -489,73 +489,42 @@ static void __init sme_clear_pgd(pgd_t *pgd_base, unsigned long start,
> static void __init *sme_populate_pgd(pgd_t *pgd_base, void *pgtable_area,
> unsigned long vaddr, pmdval_t pmd_val)
> {
> - pgd_t *pgd_p;
> - p4d_t *p4d_p;
> - pud_t *pud_p;
> - pmd_t *pmd_p;
> -
> - pgd_p = pgd_base + pgd_index(vaddr);
> - if (native_pgd_val(*pgd_p)) {
> - if (IS_ENABLED(CONFIG_X86_5LEVEL))
> - p4d_p = (p4d_t *)(native_pgd_val(*pgd_p) & ~PTE_FLAGS_MASK);
> - else
> - pud_p = (pud_t *)(native_pgd_val(*pgd_p) & ~PTE_FLAGS_MASK);
> - } else {
> - pgd_t pgd;
> -
> - if (IS_ENABLED(CONFIG_X86_5LEVEL)) {
> - p4d_p = pgtable_area;
> - memset(p4d_p, 0, sizeof(*p4d_p) * PTRS_PER_P4D);
> - pgtable_area += sizeof(*p4d_p) * PTRS_PER_P4D;
> -
> - pgd = native_make_pgd((pgdval_t)p4d_p + PGD_FLAGS);
> - } else {
> - pud_p = pgtable_area;
> - memset(pud_p, 0, sizeof(*pud_p) * PTRS_PER_PUD);
> - pgtable_area += sizeof(*pud_p) * PTRS_PER_PUD;
> -
> - pgd = native_make_pgd((pgdval_t)pud_p + PGD_FLAGS);
> - }
> - native_set_pgd(pgd_p, pgd);
> + pgd_t *pgd;
> + p4d_t *p4d;
> + pud_t *pud;
> + pmd_t *pmd;
> +
> + pgd = pgd_base + pgd_index(vaddr);
> + if (pgd_none(*pgd)) {
> + p4d = pgtable_area;
> + memset(p4d, 0, sizeof(*p4d) * PTRS_PER_P4D);
> + pgtable_area += sizeof(*p4d) * PTRS_PER_P4D;
> + native_set_pgd(pgd, __pgd(PGD_FLAGS | __pa(p4d)));
> }
>
> - if (IS_ENABLED(CONFIG_X86_5LEVEL)) {
> - p4d_p += p4d_index(vaddr);
> - if (native_p4d_val(*p4d_p)) {
> - pud_p = (pud_t *)(native_p4d_val(*p4d_p) & ~PTE_FLAGS_MASK);
> - } else {
> - p4d_t p4d;
> -
> - pud_p = pgtable_area;
> - memset(pud_p, 0, sizeof(*pud_p) * PTRS_PER_PUD);
> - pgtable_area += sizeof(*pud_p) * PTRS_PER_PUD;
> -
> - p4d = native_make_p4d((pudval_t)pud_p + P4D_FLAGS);
> - native_set_p4d(p4d_p, p4d);
> - }
> + p4d = p4d_offset(pgd, vaddr);
> + if (p4d_none(*p4d)) {
> + pud = pgtable_area;
> + memset(pud, 0, sizeof(*pud) * PTRS_PER_PUD);
> + pgtable_area += sizeof(*pud) * PTRS_PER_PUD;
> + native_set_p4d(p4d, __p4d(P4D_FLAGS | __pa(pud)));
> }
>
> - pud_p += pud_index(vaddr);
> - if (native_pud_val(*pud_p)) {
> - if (native_pud_val(*pud_p) & _PAGE_PSE)
> - goto out;
> -
> - pmd_p = (pmd_t *)(native_pud_val(*pud_p) & ~PTE_FLAGS_MASK);
> - } else {
> - pud_t pud;
> -
> - pmd_p = pgtable_area;
> - memset(pmd_p, 0, sizeof(*pmd_p) * PTRS_PER_PMD);
> - pgtable_area += sizeof(*pmd_p) * PTRS_PER_PMD;
> -
> - pud = native_make_pud((pmdval_t)pmd_p + PUD_FLAGS);
> - native_set_pud(pud_p, pud);
> + pud = pud_offset(p4d, vaddr);
> + if (pud_none(*pud)) {
> + pmd = pgtable_area;
> + memset(pmd, 0, sizeof(*pmd) * PTRS_PER_PMD);
> + pgtable_area += sizeof(*pmd) * PTRS_PER_PMD;
> + native_set_pud(pud, __pud(PUD_FLAGS | __pa(pmd)));
> }
> + if (pud_large(*pud))
> + goto out;
>
> - pmd_p += pmd_index(vaddr);
> - if (!native_pmd_val(*pmd_p) || !(native_pmd_val(*pmd_p) & _PAGE_PSE))
> - native_set_pmd(pmd_p, native_make_pmd(pmd_val));
> + pmd = pmd_offset(pud, vaddr);
> + if (pmd_large(*pmd))
> + goto out;
>
> + native_set_pmd(pmd, native_make_pmd(pmd_val));
> out:
> return pgtable_area;
> }
>

\
 
 \ /
  Last update: 2017-12-04 15:20    [W:0.053 / U:6.988 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site