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x86/mm: Use a struct to reduce parameters for SME PGD mapping
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In preparation for follow-on patches, combine the PGD mapping parameters
into a struct to reduce the number of function arguments and allow for
direct updating of the next pagetable mapping area pointer.

Tested-by: Gabriel Craciunescu <[email protected]>
Signed-off-by: Tom Lendacky <[email protected]>
Reviewed-by: Borislav Petkov <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Brijesh Singh <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>
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@tlendacky
tlendacky authored and Ingo Molnar committed Jan 16, 2018
1 parent 1303880 commit bacf6b4
Showing 1 changed file with 46 additions and 44 deletions.
90 changes: 46 additions & 44 deletions arch/x86/mm/mem_encrypt.c
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Original file line number Diff line number Diff line change
Expand Up @@ -464,6 +464,14 @@ void swiotlb_set_mem_attributes(void *vaddr, unsigned long size)
set_memory_decrypted((unsigned long)vaddr, size >> PAGE_SHIFT);
}

struct sme_populate_pgd_data {
void *pgtable_area;
pgd_t *pgd;

pmdval_t pmd_val;
unsigned long vaddr;
};

static void __init sme_clear_pgd(pgd_t *pgd_base, unsigned long start,
unsigned long end)
{
Expand All @@ -486,15 +494,14 @@ static void __init sme_clear_pgd(pgd_t *pgd_base, unsigned long start,
#define PUD_FLAGS _KERNPG_TABLE_NOENC
#define PMD_FLAGS (__PAGE_KERNEL_LARGE_EXEC & ~_PAGE_GLOBAL)

static void __init *sme_populate_pgd(pgd_t *pgd_base, void *pgtable_area,
unsigned long vaddr, pmdval_t pmd_val)
static void __init sme_populate_pgd_large(struct sme_populate_pgd_data *ppd)
{
pgd_t *pgd_p;
p4d_t *p4d_p;
pud_t *pud_p;
pmd_t *pmd_p;

pgd_p = pgd_base + pgd_index(vaddr);
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);
Expand All @@ -504,60 +511,57 @@ static void __init *sme_populate_pgd(pgd_t *pgd_base, void *pgtable_area,
pgd_t pgd;

if (IS_ENABLED(CONFIG_X86_5LEVEL)) {
p4d_p = pgtable_area;
p4d_p = ppd->pgtable_area;
memset(p4d_p, 0, sizeof(*p4d_p) * PTRS_PER_P4D);
pgtable_area += 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 = pgtable_area;
pud_p = ppd->pgtable_area;
memset(pud_p, 0, sizeof(*pud_p) * PTRS_PER_PUD);
pgtable_area += 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);
}

if (IS_ENABLED(CONFIG_X86_5LEVEL)) {
p4d_p += p4d_index(vaddr);
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 = pgtable_area;
pud_p = ppd->pgtable_area;
memset(pud_p, 0, sizeof(*pud_p) * PTRS_PER_PUD);
pgtable_area += 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);
}
}

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

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

pmd_p = pgtable_area;
pmd_p = ppd->pgtable_area;
memset(pmd_p, 0, sizeof(*pmd_p) * PTRS_PER_PMD);
pgtable_area += 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);
}

pmd_p += pmd_index(vaddr);
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(pmd_val));

out:
return pgtable_area;
native_set_pmd(pmd_p, native_make_pmd(ppd->pmd_val));
}

static unsigned long __init sme_pgtable_calc(unsigned long len)
Expand Down Expand Up @@ -615,11 +619,10 @@ void __init sme_encrypt_kernel(void)
unsigned long workarea_start, workarea_end, workarea_len;
unsigned long execute_start, execute_end, execute_len;
unsigned long kernel_start, kernel_end, kernel_len;
struct sme_populate_pgd_data ppd;
unsigned long pgtable_area_len;
unsigned long paddr, pmd_flags;
unsigned long decrypted_base;
void *pgtable_area;
pgd_t *pgd;

if (!sme_active())
return;
Expand Down Expand Up @@ -683,18 +686,18 @@ void __init sme_encrypt_kernel(void)
* pagetables and when the new encrypted and decrypted kernel
* mappings are populated.
*/
pgtable_area = (void *)execute_end;
ppd.pgtable_area = (void *)execute_end;

/*
* Make sure the current pagetable structure has entries for
* addressing the workarea.
*/
pgd = (pgd_t *)native_read_cr3_pa();
ppd.pgd = (pgd_t *)native_read_cr3_pa();
paddr = workarea_start;
while (paddr < workarea_end) {
pgtable_area = sme_populate_pgd(pgd, pgtable_area,
paddr,
paddr + PMD_FLAGS);
ppd.pmd_val = paddr + PMD_FLAGS;
ppd.vaddr = paddr;
sme_populate_pgd_large(&ppd);

paddr += PMD_PAGE_SIZE;
}
Expand All @@ -708,17 +711,17 @@ void __init sme_encrypt_kernel(void)
* populated with new PUDs and PMDs as the encrypted and decrypted
* kernel mappings are created.
*/
pgd = pgtable_area;
memset(pgd, 0, sizeof(*pgd) * PTRS_PER_PGD);
pgtable_area += sizeof(*pgd) * PTRS_PER_PGD;
ppd.pgd = ppd.pgtable_area;
memset(ppd.pgd, 0, sizeof(pgd_t) * PTRS_PER_PGD);
ppd.pgtable_area += sizeof(pgd_t) * PTRS_PER_PGD;

/* Add encrypted kernel (identity) mappings */
pmd_flags = PMD_FLAGS | _PAGE_ENC;
paddr = kernel_start;
while (paddr < kernel_end) {
pgtable_area = sme_populate_pgd(pgd, pgtable_area,
paddr,
paddr + pmd_flags);
ppd.pmd_val = paddr + pmd_flags;
ppd.vaddr = paddr;
sme_populate_pgd_large(&ppd);

paddr += PMD_PAGE_SIZE;
}
Expand All @@ -736,40 +739,39 @@ void __init sme_encrypt_kernel(void)
pmd_flags = (PMD_FLAGS & ~_PAGE_CACHE_MASK) | (_PAGE_PAT | _PAGE_PWT);
paddr = kernel_start;
while (paddr < kernel_end) {
pgtable_area = sme_populate_pgd(pgd, pgtable_area,
paddr + decrypted_base,
paddr + pmd_flags);
ppd.pmd_val = paddr + pmd_flags;
ppd.vaddr = paddr + decrypted_base;
sme_populate_pgd_large(&ppd);

paddr += PMD_PAGE_SIZE;
}

/* Add decrypted workarea mappings to both kernel mappings */
paddr = workarea_start;
while (paddr < workarea_end) {
pgtable_area = sme_populate_pgd(pgd, pgtable_area,
paddr,
paddr + PMD_FLAGS);
ppd.pmd_val = paddr + PMD_FLAGS;
ppd.vaddr = paddr;
sme_populate_pgd_large(&ppd);

pgtable_area = sme_populate_pgd(pgd, pgtable_area,
paddr + decrypted_base,
paddr + PMD_FLAGS);
ppd.vaddr = paddr + decrypted_base;
sme_populate_pgd_large(&ppd);

paddr += PMD_PAGE_SIZE;
}

/* Perform the encryption */
sme_encrypt_execute(kernel_start, kernel_start + decrypted_base,
kernel_len, workarea_start, (unsigned long)pgd);
kernel_len, workarea_start, (unsigned long)ppd.pgd);

/*
* At this point we are running encrypted. Remove the mappings for
* the decrypted areas - all that is needed for this is to remove
* the PGD entry/entries.
*/
sme_clear_pgd(pgd, kernel_start + decrypted_base,
sme_clear_pgd(ppd.pgd, kernel_start + decrypted_base,
kernel_end + decrypted_base);

sme_clear_pgd(pgd, workarea_start + decrypted_base,
sme_clear_pgd(ppd.pgd, workarea_start + decrypted_base,
workarea_end + decrypted_base);

/* Flush the TLB - no globals so cr3 is enough */
Expand Down

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