Re: [kvm-unit-tests PATCH] arm64: Add support for configuring the translation granule

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Hi Alex,

On 30/10/2020 10:46, Alexandru Elisei wrote:

Hi Nikos,

I scanned the patches, will try to do a proper review next week. Some suggestions
below.



Thanks for the review!


On 10/29/20 3:52 PM, Nikos Nikoleris wrote:

Make the translation granule configurable for arm64. arm64 supports
page sizes of 4K, 16K and 64K. By default, arm64 is configured with
64K pages. configure has been extended with a new argument:

  --page-shift=(12|14|16)


How about --page-size=4K/16K/64K, which accepts lower and upper case 'k'?
> It might be just me, because I'm not familiar with memory management, 
but each

time I see page-shift I need to do the math in my head to get to the page size. I
think page-size is more intuitive. It's also somewhat similar to the kernel config
(CONFIG_ARM64_4K_PAGES, for example, and not CONFIG_ARM64_PAGE_SHIFT_12).
You're right setting the page size is more intiutive. I had started implementing it that way but I got worried about the added complexity. I tried it again now and it doesn't look that bad. I'll post a v2 that allows you to configure the page size instead. 


I might have missed it in the patch, how about printing an error message when the
configured page size is not supported by the hardware? kvm-unit-tests runs C code
before creating the page tables, and the UART is available very early, so it
shouldn't be too hard. We can put the check in setup_mmu().
It's not there and it makes sense to check. Right now if we configure an unsupported page size, tests appear to be running just fine - you only find out when they time out. 

Thanks,

Nikos


Thanks,
Alex


which allows the user to set the page shift and therefore the page
size for arm64. Using the --page-shift for any other architecture
results an error message.

To allow for smaller page sizes and 42b VA, this change adds support
for 4-level and 3-level page tables. At compile time, we determine how
many levels in the page tables we needed.

Signed-off-by: Nikos Nikoleris <nikos.nikoleris@xxxxxxx>
---
  configure                     | 21 +++++++++++
  lib/arm/asm/page.h            |  4 ++
  lib/arm/asm/pgtable-hwdef.h   |  4 ++
  lib/arm/asm/pgtable.h         |  6 +++
  lib/arm/asm/thread_info.h     |  4 +-
  lib/arm64/asm/page.h          | 17 ++++++---
  lib/arm64/asm/pgtable-hwdef.h | 38 +++++++++++++------
  lib/arm64/asm/pgtable.h       | 69 +++++++++++++++++++++++++++++++++--
  lib/arm/mmu.c                 | 26 ++++++++-----
  arm/cstart64.S                | 12 +++++-
  10 files changed, 169 insertions(+), 32 deletions(-)

diff --git a/configure b/configure
index 706aab5..94637ec 100755
--- a/configure
+++ b/configure
@@ -25,6 +25,7 @@ vmm="qemu"
  errata_force=0
  erratatxt="$srcdir/errata.txt"
  host_key_document=
+page_shift=
usage() { 
      cat <<-EOF
@@ -105,6 +106,9 @@ while [[ "$1" = -* ]]; do
  	--host-key-document)
  	    host_key_document="$arg"
  	    ;;
+        --page-shift)
+            page_shift="$arg"
+            ;;
  	--help)
  	    usage
  	    ;;
@@ -123,6 +127,22 @@ arch_name=$arch
  [ "$arch" = "aarch64" ] && arch="arm64"
  [ "$arch_name" = "arm64" ] && arch_name="aarch64"
+if [ -z "$page_shift" ]; then 
+    [ "$arch" = "arm64" ] && page_shift="16"
+    [ "$arch" = "arm" ] && page_shift="12"
+else
+    if [ "$arch" != "arm64" ]; then
+        echo "--page-shift is not supported for $arch"
+        usage
+    fi
+
+    if [ "$page_shift" != "12" ] && [ "$page_shift" != "14" ] &&
+           [ "$page_shift" != "16" ]; then
+        echo "Page shift of $page_shift not supported for arm64"
+        usage
+    fi
+fi
+
  [ -z "$processor" ] && processor="$arch"
if [ "$processor" = "arm64" ]; then 
@@ -254,6 +274,7 @@ cat <<EOF >> lib/config.h
#define CONFIG_UART_EARLY_BASE ${arm_uart_early_addr} 
  #define CONFIG_ERRATA_FORCE ${errata_force}
+#define CONFIG_PAGE_SHIFT ${page_shift}
EOF 
  fi
diff --git a/lib/arm/asm/page.h b/lib/arm/asm/page.h
index 039c9f7..ae0ac2c 100644
--- a/lib/arm/asm/page.h
+++ b/lib/arm/asm/page.h
@@ -29,6 +29,10 @@ typedef struct { pteval_t pgprot; } pgprot_t;
  #define pgd_val(x)		((x).pgd)
  #define pgprot_val(x)		((x).pgprot)
+/* For compatibility with arm64 page tables */ 
+#define pud_t pgd_t
+#define pud_val(x) pgd_val(x)
+
  #define __pte(x)		((pte_t) { (x) } )
  #define __pmd(x)		((pmd_t) { (x) } )
  #define __pgd(x)		((pgd_t) { (x) } )
diff --git a/lib/arm/asm/pgtable-hwdef.h b/lib/arm/asm/pgtable-hwdef.h
index 4107e18..fe1d854 100644
--- a/lib/arm/asm/pgtable-hwdef.h
+++ b/lib/arm/asm/pgtable-hwdef.h
@@ -19,6 +19,10 @@
  #define PTRS_PER_PTE		512
  #define PTRS_PER_PMD		512
+/* For compatibility with arm64 page tables */ 
+#define PUD_SIZE		PGDIR_SIZE
+#define PUD_MASK		PGDIR_MASK
+
  #define PMD_SHIFT		21
  #define PMD_SIZE		(_AC(1,UL) << PMD_SHIFT)
  #define PMD_MASK		(~((1 << PMD_SHIFT) - 1))
diff --git a/lib/arm/asm/pgtable.h b/lib/arm/asm/pgtable.h
index 078dd16..4759d82 100644
--- a/lib/arm/asm/pgtable.h
+++ b/lib/arm/asm/pgtable.h
@@ -53,6 +53,12 @@ static inline pmd_t *pgd_page_vaddr(pgd_t pgd)
  	return pgtable_va(pgd_val(pgd) & PHYS_MASK & (s32)PAGE_MASK);
  }
+/* For compatibility with arm64 page tables */ 
+#define pud_valid(pud)		pgd_valid(pud)
+#define pud_offset(pgd, addr)  ((pud_t *)pgd)
+#define pud_free(pud)
+#define pud_alloc(pgd, addr)   pud_offset(pgd, addr)
+
  #define pmd_index(addr) \
  	(((addr) >> PMD_SHIFT) & (PTRS_PER_PMD - 1))
  #define pmd_offset(pgd, addr) \
diff --git a/lib/arm/asm/thread_info.h b/lib/arm/asm/thread_info.h
index 80ab395..eaa7258 100644
--- a/lib/arm/asm/thread_info.h
+++ b/lib/arm/asm/thread_info.h
@@ -14,10 +14,12 @@
  #define THREAD_SHIFT		PAGE_SHIFT
  #define THREAD_SIZE		PAGE_SIZE
  #define THREAD_MASK		PAGE_MASK
+#define THREAD_ALIGNMENT	PAGE_SIZE
  #else
  #define THREAD_SHIFT		MIN_THREAD_SHIFT
  #define THREAD_SIZE		(_AC(1,UL) << THREAD_SHIFT)
  #define THREAD_MASK		(~(THREAD_SIZE-1))
+#define THREAD_ALIGNMENT	THREAD_SIZE
  #endif
#ifndef __ASSEMBLY__ 
@@ -38,7 +40,7 @@
static inline void *thread_stack_alloc(void) 
  {
-	void *sp = memalign(PAGE_SIZE, THREAD_SIZE);
+	void *sp = memalign(THREAD_ALIGNMENT, THREAD_SIZE);
  	return sp + THREAD_START_SP;
  }
diff --git a/lib/arm64/asm/page.h b/lib/arm64/asm/page.h 
index 46af552..726a0c0 100644
--- a/lib/arm64/asm/page.h
+++ b/lib/arm64/asm/page.h
@@ -10,38 +10,43 @@
   * This work is licensed under the terms of the GNU GPL, version 2.
   */
+#include <config.h> 
  #include <linux/const.h>
-#define PGTABLE_LEVELS 2 
  #define VA_BITS			42
-#define PAGE_SHIFT 16 
+#define PAGE_SHIFT		CONFIG_PAGE_SHIFT
  #define PAGE_SIZE		(_AC(1,UL) << PAGE_SHIFT)
  #define PAGE_MASK		(~(PAGE_SIZE-1))
+#define PGTABLE_LEVELS (((VA_BITS) - 4) / (PAGE_SHIFT - 3)) 
+
  #ifndef __ASSEMBLY__
#define PAGE_ALIGN(addr) ALIGN(addr, PAGE_SIZE) typedef u64 pteval_t; 
  typedef u64 pmdval_t;
+typedef u64 pudval_t;
  typedef u64 pgdval_t;
  typedef struct { pteval_t pte; } pte_t;
+typedef struct { pmdval_t pmd; } pmd_t;
+typedef struct { pudval_t pud; } pud_t;
  typedef struct { pgdval_t pgd; } pgd_t;
  typedef struct { pteval_t pgprot; } pgprot_t;
#define pte_val(x) ((x).pte) 
+#define pmd_val(x)		((x).pmd)
+#define pud_val(x)		((x).pud)
  #define pgd_val(x)		((x).pgd)
  #define pgprot_val(x)		((x).pgprot)
#define __pte(x) ((pte_t) { (x) } ) 
+#define __pmd(x)		((pmd_t) { (x) } )
+#define __pud(x)		((pud_t) { (x) } )
  #define __pgd(x)		((pgd_t) { (x) } )
  #define __pgprot(x)		((pgprot_t) { (x) } )
-typedef struct { pgd_t pgd; } pmd_t; 
-#define pmd_val(x)		(pgd_val((x).pgd))
-#define __pmd(x)		((pmd_t) { __pgd(x) } )
-
  #define __va(x)			((void *)__phys_to_virt((phys_addr_t)(x)))
  #define __pa(x)			__virt_to_phys((unsigned long)(x))
diff --git a/lib/arm64/asm/pgtable-hwdef.h b/lib/arm64/asm/pgtable-hwdef.h 
index 3352489..f9110e1 100644
--- a/lib/arm64/asm/pgtable-hwdef.h
+++ b/lib/arm64/asm/pgtable-hwdef.h
@@ -9,38 +9,54 @@
   * This work is licensed under the terms of the GNU GPL, version 2.
   */
+#include <asm/page.h> 
+
  #define UL(x) _AC(x, UL)
+#define PGTABLE_LEVEL_SHIFT(n) ((PAGE_SHIFT - 3) * (4 - (n)) + 3) 
  #define PTRS_PER_PTE		(1 << (PAGE_SHIFT - 3))
+#if PGTABLE_LEVELS > 2 
+#define PMD_SHIFT		PGTABLE_LEVEL_SHIFT(2)
+#define PTRS_PER_PMD		PTRS_PER_PTE
+#define PMD_SIZE		(UL(1) << PMD_SHIFT)
+#define PMD_MASK		(~(PMD_SIZE-1))
+#endif
+
+#if PGTABLE_LEVELS > 3
+#define PUD_SHIFT		PGTABLE_LEVEL_SHIFT(1)
+#define PTRS_PER_PUD		PTRS_PER_PTE
+#define PUD_SIZE		(UL(1) << PUD_SHIFT)
+#define PUD_MASK		(~(PUD_SIZE-1))
+#else
+#define PUD_SIZE                PGDIR_SIZE
+#define PUD_MASK                PGDIR_MASK
+#endif
+
+#define PUD_VALID		(_AT(pudval_t, 1) << 0)
+
  /*
   * PGDIR_SHIFT determines the size a top-level page table entry can map
   * (depending on the configuration, this level can be 0, 1 or 2).
   */
-#define PGDIR_SHIFT		((PAGE_SHIFT - 3) * PGTABLE_LEVELS + 3)
+#define PGDIR_SHIFT		PGTABLE_LEVEL_SHIFT(4 - PGTABLE_LEVELS)
  #define PGDIR_SIZE		(_AC(1, UL) << PGDIR_SHIFT)
  #define PGDIR_MASK		(~(PGDIR_SIZE-1))
  #define PTRS_PER_PGD		(1 << (VA_BITS - PGDIR_SHIFT))
#define PGD_VALID (_AT(pgdval_t, 1) << 0) -/* From include/asm-generic/pgtable-nopmd.h */ 
-#define PMD_SHIFT		PGDIR_SHIFT
-#define PTRS_PER_PMD		1
-#define PMD_SIZE		(UL(1) << PMD_SHIFT)
-#define PMD_MASK		(~(PMD_SIZE-1))
-
  /*
   * Section address mask and size definitions.
   */
-#define SECTION_SHIFT		PMD_SHIFT
-#define SECTION_SIZE		(_AC(1, UL) << SECTION_SHIFT)
-#define SECTION_MASK		(~(SECTION_SIZE-1))
+#define SECTION_SHIFT          PMD_SHIFT
+#define SECTION_SIZE           (_AC(1, UL) << SECTION_SHIFT)
+#define SECTION_MASK           (~(SECTION_SIZE-1))
/* 
   * Hardware page table definitions.
   *
- * Level 1 descriptor (PMD).
+ * Level 0,1,2 descriptor (PGG, PUD and PMD).
   */
  #define PMD_TYPE_MASK		(_AT(pmdval_t, 3) << 0)
  #define PMD_TYPE_FAULT		(_AT(pmdval_t, 0) << 0)
diff --git a/lib/arm64/asm/pgtable.h b/lib/arm64/asm/pgtable.h
index e577d9c..c7632ae 100644
--- a/lib/arm64/asm/pgtable.h
+++ b/lib/arm64/asm/pgtable.h
@@ -30,10 +30,12 @@
  #define pgtable_pa(x)		((unsigned long)(x))
#define pgd_none(pgd) (!pgd_val(pgd)) 
+#define pud_none(pud)		(!pud_val(pud))
  #define pmd_none(pmd)		(!pmd_val(pmd))
  #define pte_none(pte)		(!pte_val(pte))
#define pgd_valid(pgd) (pgd_val(pgd) & PGD_VALID) 
+#define pud_valid(pud)		(pud_val(pud) & PUD_VALID)
  #define pmd_valid(pmd)		(pmd_val(pmd) & PMD_SECT_VALID)
  #define pte_valid(pte)		(pte_val(pte) & PTE_VALID)
@@ -52,15 +54,76 @@ static inline pgd_t *pgd_alloc(void) 
  	return pgd;
  }
-#define pmd_offset(pgd, addr) ((pmd_t *)pgd) 
-#define pmd_free(pmd)
-#define pmd_alloc(pgd, addr)	pmd_offset(pgd, addr)
+static inline pud_t *pgd_page_vaddr(pgd_t pgd)
+{
+	return pgtable_va(pgd_val(pgd) & PHYS_MASK & (s32)PAGE_MASK);
+}
+
+static inline pmd_t *pud_page_vaddr(pud_t pud)
+{
+	return pgtable_va(pud_val(pud) & PHYS_MASK & (s32)PAGE_MASK);
+}
+
static inline pte_t *pmd_page_vaddr(pmd_t pmd) 
  {
  	return pgtable_va(pmd_val(pmd) & PHYS_MASK & (s32)PAGE_MASK);
  }
+#if PGTABLE_LEVELS > 2 
+#define pmd_index(addr)					\
+	(((addr) >> PMD_SHIFT) & (PTRS_PER_PMD - 1))
+#define pmd_offset(pud, addr)				\
+	(pud_page_vaddr(*(pud)) + pmd_index(addr))
+#define pmd_free(pmd) free_page(pmd)
+static inline pmd_t *pmd_alloc_one(void)
+{
+	assert(PTRS_PER_PMD * sizeof(pmd_t) == PAGE_SIZE);
+	pmd_t *pmd = alloc_page();
+	return pmd;
+}
+static inline pmd_t *pmd_alloc(pud_t *pud, unsigned long addr)
+{
+        if (pud_none(*pud)) {
+		pud_t entry;
+		pud_val(entry) = pgtable_pa(pmd_alloc_one()) | PMD_TYPE_TABLE;
+		WRITE_ONCE(*pud, entry);
+	}
+	return pmd_offset(pud, addr);
+}
+#else
+#define pmd_offset(pud, addr)  ((pmd_t *)pud)
+#define pmd_free(pmd)
+#define pmd_alloc(pud, addr)   pmd_offset(pud, addr)
+#endif
+
+#if PGTABLE_LEVELS > 3
+#define pud_index(addr)                                 \
+	(((addr) >> PUD_SHIFT) & (PTRS_PER_PUD - 1))
+#define pud_offset(pgd, addr)                           \
+	(pgd_page_vaddr(*(pgd)) + pud_index(addr))
+#define pud_free(pud) free_page(pud)
+static inline pud_t *pud_alloc_one(void)
+{
+	assert(PTRS_PER_PMD * sizeof(pud_t) == PAGE_SIZE);
+	pud_t *pud = alloc_page();
+	return pud;
+}
+static inline pud_t *pud_alloc(pgd_t *pgd, unsigned long addr)
+{
+	if (pgd_none(*pgd)) {
+		pgd_t entry;
+		pgd_val(entry) = pgtable_pa(pud_alloc_one()) | PMD_TYPE_TABLE;
+		WRITE_ONCE(*pgd, entry);
+	}
+	return pud_offset(pgd, addr);
+}
+#else
+#define pud_offset(pgd, addr)  ((pud_t *)pgd)
+#define pud_free(pud)
+#define pud_alloc(pgd, addr)   pud_offset(pgd, addr)
+#endif
+
  #define pte_index(addr) \
  	(((addr) >> PAGE_SHIFT) & (PTRS_PER_PTE - 1))
  #define pte_offset(pmd, addr) \
diff --git a/lib/arm/mmu.c b/lib/arm/mmu.c
index 540a1e8..6d1c75b 100644
--- a/lib/arm/mmu.c
+++ b/lib/arm/mmu.c
@@ -81,7 +81,8 @@ void mmu_disable(void)
  static pteval_t *get_pte(pgd_t *pgtable, uintptr_t vaddr)
  {
  	pgd_t *pgd = pgd_offset(pgtable, vaddr);
-	pmd_t *pmd = pmd_alloc(pgd, vaddr);
+	pud_t *pud = pud_alloc(pgd, vaddr);
+	pmd_t *pmd = pmd_alloc(pud, vaddr);
  	pte_t *pte = pte_alloc(pmd, vaddr);
return &pte_val(*pte); 
@@ -133,18 +134,20 @@ void mmu_set_range_sect(pgd_t *pgtable, uintptr_t virt_offset,
  			phys_addr_t phys_start, phys_addr_t phys_end,
  			pgprot_t prot)
  {
-	phys_addr_t paddr = phys_start & PGDIR_MASK;
-	uintptr_t vaddr = virt_offset & PGDIR_MASK;
+	phys_addr_t paddr = phys_start & PUD_MASK;
+	uintptr_t vaddr = virt_offset & PUD_MASK;
  	uintptr_t virt_end = phys_end - paddr + vaddr;
  	pgd_t *pgd;
-	pgd_t entry;
+	pud_t *pud;
+	pud_t entry;
- for (; vaddr < virt_end; vaddr += PGDIR_SIZE, paddr += PGDIR_SIZE) { 
-		pgd_val(entry) = paddr;
-		pgd_val(entry) |= PMD_TYPE_SECT | PMD_SECT_AF | PMD_SECT_S;
-		pgd_val(entry) |= pgprot_val(prot);
+	for (; vaddr < virt_end; vaddr += PUD_SIZE, paddr += PUD_SIZE) {
+		pud_val(entry) = paddr;
+		pud_val(entry) |= PMD_TYPE_SECT | PMD_SECT_AF | PMD_SECT_S;
+		pud_val(entry) |= pgprot_val(prot);
  		pgd = pgd_offset(pgtable, vaddr);
-		WRITE_ONCE(*pgd, entry);
+		pud = pud_alloc(pgd, vaddr);
+		WRITE_ONCE(*pud, entry);
  		flush_tlb_page(vaddr);
  	}
  }
@@ -207,6 +210,7 @@ unsigned long __phys_to_virt(phys_addr_t addr)
  void mmu_clear_user(pgd_t *pgtable, unsigned long vaddr)
  {
  	pgd_t *pgd;
+	pud_t *pud;
  	pmd_t *pmd;
  	pte_t *pte;
@@ -215,7 +219,9 @@ void mmu_clear_user(pgd_t *pgtable, unsigned long vaddr) pgd = pgd_offset(pgtable, vaddr); 
  	assert(pgd_valid(*pgd));
-	pmd = pmd_offset(pgd, vaddr);
+	pud = pud_offset(pgd, vaddr);
+	assert(pud_valid(*pud));
+	pmd = pmd_offset(pud, vaddr);
  	assert(pmd_valid(*pmd));
if (pmd_huge(*pmd)) { 
diff --git a/arm/cstart64.S b/arm/cstart64.S
index ffdd49f..530ffb6 100644
--- a/arm/cstart64.S
+++ b/arm/cstart64.S
@@ -157,6 +157,16 @@ halt:
   */
  #define MAIR(attr, mt) ((attr) << ((mt) * 8))
+#if PAGE_SHIFT == 16 
+#define TCR_TG_FLAGS	TCR_TG0_64K | TCR_TG1_64K
+#elif PAGE_SHIFT == 14
+#define TCR_TG_FLAGS	TCR_TG0_16K | TCR_TG1_16K
+#elif PAGE_SHIFT == 12
+#define TCR_TG_FLAGS	TCR_TG0_4K | TCR_TG1_4K
+#else
+#error Unsupported PAGE_SHIFT
+#endif
+
  .globl asm_mmu_enable
  asm_mmu_enable:
  	tlbi	vmalle1			// invalidate I + D TLBs
@@ -164,7 +174,7 @@ asm_mmu_enable:
/* TCR */ 
  	ldr	x1, =TCR_TxSZ(VA_BITS) |		\
-		     TCR_TG0_64K | TCR_TG1_64K |	\
+		     TCR_TG_FLAGS  |			\
  		     TCR_IRGN_WBWA | TCR_ORGN_WBWA |	\
  		     TCR_SHARED
  	mrs	x2, id_aa64mmfr0_el1
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