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Subject[tip:x86/mm] x86/mm/encrypt: Simplify sme_populate_pgd() and sme_populate_pgd_large()
Commit-ID:  aad983913d77af2c3394f29b88d7bb75ebd7d172
Gitweb: https://git.kernel.org/tip/aad983913d77af2c3394f29b88d7bb75ebd7d172
Author: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
AuthorDate: Wed, 31 Jan 2018 16:54:03 +0300
Committer: Ingo Molnar <mingo@kernel.org>
CommitDate: Tue, 13 Feb 2018 15:59:49 +0100

x86/mm/encrypt: Simplify sme_populate_pgd() and sme_populate_pgd_large()

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>
---
arch/x86/mm/mem_encrypt_identity.c | 159 +++++++++++++++++--------------------
1 file changed, 72 insertions(+), 87 deletions(-)

diff --git a/arch/x86/mm/mem_encrypt_identity.c b/arch/x86/mm/mem_encrypt_identity.c
index a28978a..4b6a2e3 100644
--- a/arch/x86/mm/mem_encrypt_identity.c
+++ b/arch/x86/mm/mem_encrypt_identity.c
@@ -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>

@@ -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)
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