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x86/mm/encrypt: Simplify sme_populate_pgd() and sme_populate_pgd_large()
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sme_populate_pgd() and sme_populate_pgd_large() operate on the identity
mapping, which means they want virtual addresses to be equal to physical
one, without PAGE_OFFSET shift.

We also need to avoid paravirtualization call there.

Getting this done is tricky. We cannot use usual page table helpers.
It forces us to open-code a lot of things. It makes code ugly and hard
to modify.

We can get it work with the page table helpers, but it requires few
preprocessor tricks.

  - Define __pa() and __va() to be compatible with identity mapping.

  - Undef CONFIG_PARAVIRT and CONFIG_PARAVIRT_SPINLOCKS before including
    any file. This way we can avoid paravirtualization calls.

Now we can user normal page table helpers just fine.

Tested-by: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reviewed-by: Tom Lendacky <thomas.lendacky@amd.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-mm@kvack.org
Link: http://lkml.kernel.org/r/20180131135404.40692-3-kirill.shutemov@linux.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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@kiryl
kiryl authored and Ingo Molnar committed Feb 13, 2018
1 parent 1cd9c22 commit aad9839
Showing 1 changed file with 72 additions and 87 deletions.
159 changes: 72 additions & 87 deletions arch/x86/mm/mem_encrypt_identity.c
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Original file line number Diff line number Diff line change
Expand Up @@ -12,6 +12,24 @@

#define DISABLE_BRANCH_PROFILING

/*
* Since we're dealing with identity mappings, physical and virtual
* addresses are the same, so override these defines which are ultimately
* used by the headers in misc.h.
*/
#define __pa(x) ((unsigned long)(x))
#define __va(x) ((void *)((unsigned long)(x)))

/*
* Special hack: we have to be careful, because no indirections are
* allowed here, and paravirt_ops is a kind of one. As it will only run in
* baremetal anyway, we just keep it from happening. (This list needs to
* be extended when new paravirt and debugging variants are added.)
*/
#undef CONFIG_PARAVIRT
#undef CONFIG_PARAVIRT_SPINLOCKS

#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/mem_encrypt.h>

Expand Down Expand Up @@ -73,116 +91,83 @@ static void __init sme_clear_pgd(struct sme_populate_pgd_data *ppd)
memset(pgd_p, 0, pgd_size);
}

static pmd_t __init *sme_prepare_pgd(struct sme_populate_pgd_data *ppd)
static pud_t __init *sme_prepare_pgd(struct sme_populate_pgd_data *ppd)
{
pgd_t *pgd_p;
p4d_t *p4d_p;
pud_t *pud_p;
pmd_t *pmd_p;

pgd_p = ppd->pgd + pgd_index(ppd->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 = ppd->pgtable_area;
memset(p4d_p, 0, sizeof(*p4d_p) * PTRS_PER_P4D);
ppd->pgtable_area += sizeof(*p4d_p) * PTRS_PER_P4D;

pgd = native_make_pgd((pgdval_t)p4d_p + PGD_FLAGS);
} else {
pud_p = ppd->pgtable_area;
memset(pud_p, 0, sizeof(*pud_p) * PTRS_PER_PUD);
ppd->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 = ppd->pgd + pgd_index(ppd->vaddr);
if (pgd_none(*pgd)) {
p4d = ppd->pgtable_area;
memset(p4d, 0, sizeof(*p4d) * PTRS_PER_P4D);
ppd->pgtable_area += sizeof(*p4d) * PTRS_PER_P4D;
set_pgd(pgd, __pgd(PGD_FLAGS | __pa(p4d)));
}

if (IS_ENABLED(CONFIG_X86_5LEVEL)) {
p4d_p += p4d_index(ppd->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 = ppd->pgtable_area;
memset(pud_p, 0, sizeof(*pud_p) * PTRS_PER_PUD);
ppd->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, ppd->vaddr);
if (p4d_none(*p4d)) {
pud = ppd->pgtable_area;
memset(pud, 0, sizeof(*pud) * PTRS_PER_PUD);
ppd->pgtable_area += sizeof(*pud) * PTRS_PER_PUD;
set_p4d(p4d, __p4d(P4D_FLAGS | __pa(pud)));
}

pud_p += pud_index(ppd->vaddr);
if (native_pud_val(*pud_p)) {
if (native_pud_val(*pud_p) & _PAGE_PSE)
return NULL;

pmd_p = (pmd_t *)(native_pud_val(*pud_p) & ~PTE_FLAGS_MASK);
} else {
pud_t pud;

pmd_p = ppd->pgtable_area;
memset(pmd_p, 0, sizeof(*pmd_p) * PTRS_PER_PMD);
ppd->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, ppd->vaddr);
if (pud_none(*pud)) {
pmd = ppd->pgtable_area;
memset(pmd, 0, sizeof(*pmd) * PTRS_PER_PMD);
ppd->pgtable_area += sizeof(*pmd) * PTRS_PER_PMD;
set_pud(pud, __pud(PUD_FLAGS | __pa(pmd)));
}

return pmd_p;
if (pud_large(*pud))
return NULL;

return pud;
}

static void __init sme_populate_pgd_large(struct sme_populate_pgd_data *ppd)
{
pmd_t *pmd_p;
pud_t *pud;
pmd_t *pmd;

pmd_p = sme_prepare_pgd(ppd);
if (!pmd_p)
pud = sme_prepare_pgd(ppd);
if (!pud)
return;

pmd_p += pmd_index(ppd->vaddr);
if (!native_pmd_val(*pmd_p) || !(native_pmd_val(*pmd_p) & _PAGE_PSE))
native_set_pmd(pmd_p, native_make_pmd(ppd->paddr | ppd->pmd_flags));
pmd = pmd_offset(pud, ppd->vaddr);
if (pmd_large(*pmd))
return;

set_pmd(pmd, __pmd(ppd->paddr | ppd->pmd_flags));
}

static void __init sme_populate_pgd(struct sme_populate_pgd_data *ppd)
{
pmd_t *pmd_p;
pte_t *pte_p;
pud_t *pud;
pmd_t *pmd;
pte_t *pte;

pmd_p = sme_prepare_pgd(ppd);
if (!pmd_p)
pud = sme_prepare_pgd(ppd);
if (!pud)
return;

pmd_p += pmd_index(ppd->vaddr);
if (native_pmd_val(*pmd_p)) {
if (native_pmd_val(*pmd_p) & _PAGE_PSE)
return;

pte_p = (pte_t *)(native_pmd_val(*pmd_p) & ~PTE_FLAGS_MASK);
} else {
pmd_t pmd;

pte_p = ppd->pgtable_area;
memset(pte_p, 0, sizeof(*pte_p) * PTRS_PER_PTE);
ppd->pgtable_area += sizeof(*pte_p) * PTRS_PER_PTE;

pmd = native_make_pmd((pteval_t)pte_p + PMD_FLAGS);
native_set_pmd(pmd_p, pmd);
pmd = pmd_offset(pud, ppd->vaddr);
if (pmd_none(*pmd)) {
pte = ppd->pgtable_area;
memset(pte, 0, sizeof(pte) * PTRS_PER_PTE);
ppd->pgtable_area += sizeof(pte) * PTRS_PER_PTE;
set_pmd(pmd, __pmd(PMD_FLAGS | __pa(pte)));
}

pte_p += pte_index(ppd->vaddr);
if (!native_pte_val(*pte_p))
native_set_pte(pte_p, native_make_pte(ppd->paddr | ppd->pte_flags));
if (pmd_large(*pmd))
return;

pte = pte_offset_map(pmd, ppd->vaddr);
if (pte_none(*pte))
set_pte(pte, __pte(ppd->paddr | ppd->pte_flags));
}

static void __init __sme_map_range_pmd(struct sme_populate_pgd_data *ppd)
Expand Down

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