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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [xen master] xen/riscv: introduce setup_initial_pages
commit e66003e7be1996c9dd8daca54ba34ad5bb58d668
Author: Oleksii Kurochko <oleksii.kurochko@xxxxxxxxx>
AuthorDate: Wed May 31 11:55:58 2023 +0200
Commit: Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Wed May 31 11:58:31 2023 +0200
xen/riscv: introduce setup_initial_pages
The idea was taken from xvisor but the following changes
were done:
* Use only a minimal part of the code enough to enable MMU
* rename {_}setup_initial_pagetables functions
* add an argument for setup_initial_mapping to have
an opportunity to make set PTE flags.
* update setup_initial_pagetables function to map sections
with correct PTE flags.
* Rewrite enable_mmu() to C.
* map linker addresses range to load addresses range without
1:1 mapping. It will be 1:1 only in case when
load_start_addr is equal to linker_start_addr.
* add safety checks such as:
* Xen size is less than page size
* linker addresses range doesn't overlap load addresses
range
* Rework macros {THIRD,SECOND,FIRST,ZEROETH}_{SHIFT,MASK}
* change PTE_LEAF_DEFAULT to RW instead of RWX.
* Remove phys_offset as it is not used now
* Remove alignment of {map, pa}_start &= XEN_PT_LEVEL_MAP_MASK(0);
in setup_inital_mapping() as they should be already aligned.
Make a check that {map_pa}_start are aligned.
* Remove clear_pagetables() as initial pagetables will be
zeroed during bss initialization
* Remove __attribute__((section(".entry")) for setup_initial_pagetables()
as there is no such section in xen.lds.S
* Update the argument of pte_is_valid() to "const pte_t *p"
* Add check that Xen's load address is aligned at 4k boundary
* Refactor setup_initial_pagetables() so it is mapping linker
address range to load address range. After setup needed
permissions for specific section ( such as .text, .rodata, etc )
otherwise RW permission will be set by default.
* Add function to check that requested SATP_MODE is supported
Origin: git@xxxxxxxxxx:xvisor/xvisor.git 9be2fdd7
Signed-off-by: Oleksii Kurochko <oleksii.kurochko@xxxxxxxxx>
Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
Acked-by: Bobby Eshleman <bobbyeshleman@xxxxxxxxx>
---
xen/arch/riscv/Makefile | 1 +
xen/arch/riscv/include/asm/config.h | 14 +-
xen/arch/riscv/include/asm/current.h | 11 ++
xen/arch/riscv/include/asm/mm.h | 14 ++
xen/arch/riscv/include/asm/page-bits.h | 10 ++
xen/arch/riscv/include/asm/page.h | 61 ++++++++
xen/arch/riscv/include/asm/processor.h | 5 +
xen/arch/riscv/mm.c | 275 +++++++++++++++++++++++++++++++++
xen/arch/riscv/setup.c | 11 ++
xen/arch/riscv/xen.lds.S | 2 +
10 files changed, 403 insertions(+), 1 deletion(-)
diff --git a/xen/arch/riscv/Makefile b/xen/arch/riscv/Makefile
index 1156d71b38..2fefe14e7c 100644
--- a/xen/arch/riscv/Makefile
+++ b/xen/arch/riscv/Makefile
@@ -1,5 +1,6 @@
obj-$(CONFIG_EARLY_PRINTK) += early_printk.o
obj-y += entry.o
+obj-y += mm.o
obj-$(CONFIG_RISCV_64) += riscv64/
obj-y += sbi.o
obj-y += setup.o
diff --git a/xen/arch/riscv/include/asm/config.h
b/xen/arch/riscv/include/asm/config.h
index 9900d29dab..38862df0b8 100644
--- a/xen/arch/riscv/include/asm/config.h
+++ b/xen/arch/riscv/include/asm/config.h
@@ -75,12 +75,24 @@
name:
#endif
-#define XEN_VIRT_START _AT(UL, 0x80200000)
+#ifdef CONFIG_RISCV_64
+#define XEN_VIRT_START 0xFFFFFFFFC0000000 /* (_AC(-1, UL) + 1 - GB(1)) */
+#else
+#error "RV32 isn't supported"
+#endif
#define SMP_CACHE_BYTES (1 << 6)
#define STACK_SIZE PAGE_SIZE
+#ifdef CONFIG_RISCV_64
+#define CONFIG_PAGING_LEVELS 3
+#define RV_STAGE1_MODE SATP_MODE_SV39
+#else
+#define CONFIG_PAGING_LEVELS 2
+#define RV_STAGE1_MODE SATP_MODE_SV32
+#endif
+
#endif /* __RISCV_CONFIG_H__ */
/*
* Local variables:
diff --git a/xen/arch/riscv/include/asm/current.h
b/xen/arch/riscv/include/asm/current.h
new file mode 100644
index 0000000000..d87e6717e0
--- /dev/null
+++ b/xen/arch/riscv/include/asm/current.h
@@ -0,0 +1,11 @@
+#ifndef __ASM_CURRENT_H
+#define __ASM_CURRENT_H
+
+#define switch_stack_and_jump(stack, fn) do { \
+ asm volatile ( \
+ "mv sp, %0\n" \
+ "j " #fn :: "r" (stack), "X" (fn) : "memory" ); \
+ unreachable(); \
+} while ( false )
+
+#endif /* __ASM_CURRENT_H */
diff --git a/xen/arch/riscv/include/asm/mm.h b/xen/arch/riscv/include/asm/mm.h
new file mode 100644
index 0000000000..64293eacee
--- /dev/null
+++ b/xen/arch/riscv/include/asm/mm.h
@@ -0,0 +1,14 @@
+#ifndef _ASM_RISCV_MM_H
+#define _ASM_RISCV_MM_H
+
+#include <asm/page-bits.h>
+
+#define pfn_to_paddr(pfn) ((paddr_t)(pfn) << PAGE_SHIFT)
+#define paddr_to_pfn(pa) ((unsigned long)((pa) >> PAGE_SHIFT))
+
+void setup_initial_pagetables(void);
+
+void enable_mmu(void);
+void cont_after_mmu_is_enabled(void);
+
+#endif /* _ASM_RISCV_MM_H */
diff --git a/xen/arch/riscv/include/asm/page-bits.h
b/xen/arch/riscv/include/asm/page-bits.h
index 1801820294..4a3e33589a 100644
--- a/xen/arch/riscv/include/asm/page-bits.h
+++ b/xen/arch/riscv/include/asm/page-bits.h
@@ -4,4 +4,14 @@
#define PAGE_SHIFT 12 /* 4 KiB Pages */
#define PADDR_BITS 56 /* 44-bit PPN */
+#ifdef CONFIG_RISCV_64
+#define PAGETABLE_ORDER (9)
+#else /* CONFIG_RISCV_32 */
+#define PAGETABLE_ORDER (10)
+#endif
+
+#define PAGETABLE_ENTRIES (1 << PAGETABLE_ORDER)
+
+#define PTE_PPN_SHIFT 10
+
#endif /* __RISCV_PAGE_BITS_H__ */
diff --git a/xen/arch/riscv/include/asm/page.h
b/xen/arch/riscv/include/asm/page.h
new file mode 100644
index 0000000000..a7e2eee964
--- /dev/null
+++ b/xen/arch/riscv/include/asm/page.h
@@ -0,0 +1,61 @@
+#ifndef _ASM_RISCV_PAGE_H
+#define _ASM_RISCV_PAGE_H
+
+#include <xen/const.h>
+#include <xen/types.h>
+
+#include <asm/mm.h>
+#include <asm/page-bits.h>
+
+#define VPN_MASK (PAGETABLE_ENTRIES - 1UL)
+
+#define XEN_PT_LEVEL_ORDER(lvl) ((lvl) * PAGETABLE_ORDER)
+#define XEN_PT_LEVEL_SHIFT(lvl) (XEN_PT_LEVEL_ORDER(lvl) + PAGE_SHIFT)
+#define XEN_PT_LEVEL_SIZE(lvl) (_AT(paddr_t, 1) <<
XEN_PT_LEVEL_SHIFT(lvl))
+#define XEN_PT_LEVEL_MAP_MASK(lvl) (~(XEN_PT_LEVEL_SIZE(lvl) - 1))
+#define XEN_PT_LEVEL_MASK(lvl) (VPN_MASK << XEN_PT_LEVEL_SHIFT(lvl))
+
+#define PTE_VALID BIT(0, UL)
+#define PTE_READABLE BIT(1, UL)
+#define PTE_WRITABLE BIT(2, UL)
+#define PTE_EXECUTABLE BIT(3, UL)
+#define PTE_USER BIT(4, UL)
+#define PTE_GLOBAL BIT(5, UL)
+#define PTE_ACCESSED BIT(6, UL)
+#define PTE_DIRTY BIT(7, UL)
+#define PTE_RSW (BIT(8, UL) | BIT(9, UL))
+
+#define PTE_LEAF_DEFAULT (PTE_VALID | PTE_READABLE | PTE_WRITABLE)
+#define PTE_TABLE (PTE_VALID)
+
+/* Calculate the offsets into the pagetables for a given VA */
+#define pt_linear_offset(lvl, va) ((va) >> XEN_PT_LEVEL_SHIFT(lvl))
+
+#define pt_index(lvl, va) (pt_linear_offset((lvl), (va)) & VPN_MASK)
+
+/* Page Table entry */
+typedef struct {
+#ifdef CONFIG_RISCV_64
+ uint64_t pte;
+#else
+ uint32_t pte;
+#endif
+} pte_t;
+
+static inline pte_t paddr_to_pte(paddr_t paddr,
+ unsigned int permissions)
+{
+ return (pte_t) { .pte = (paddr_to_pfn(paddr) << PTE_PPN_SHIFT) |
permissions };
+}
+
+static inline paddr_t pte_to_paddr(pte_t pte)
+{
+ return pfn_to_paddr(pte.pte >> PTE_PPN_SHIFT);
+}
+
+static inline bool pte_is_valid(pte_t p)
+{
+ return p.pte & PTE_VALID;
+}
+
+#endif /* _ASM_RISCV_PAGE_H */
diff --git a/xen/arch/riscv/include/asm/processor.h
b/xen/arch/riscv/include/asm/processor.h
index a71448e02e..6db681d805 100644
--- a/xen/arch/riscv/include/asm/processor.h
+++ b/xen/arch/riscv/include/asm/processor.h
@@ -69,6 +69,11 @@ static inline void die(void)
wfi();
}
+static inline void sfence_vma(void)
+{
+ asm volatile ( "sfence.vma" ::: "memory" );
+}
+
#endif /* __ASSEMBLY__ */
#endif /* _ASM_RISCV_PROCESSOR_H */
diff --git a/xen/arch/riscv/mm.c b/xen/arch/riscv/mm.c
new file mode 100644
index 0000000000..8ceed445cf
--- /dev/null
+++ b/xen/arch/riscv/mm.c
@@ -0,0 +1,275 @@
+#include <xen/compiler.h>
+#include <xen/init.h>
+#include <xen/kernel.h>
+#include <xen/pfn.h>
+
+#include <asm/early_printk.h>
+#include <asm/csr.h>
+#include <asm/current.h>
+#include <asm/mm.h>
+#include <asm/page.h>
+#include <asm/processor.h>
+
+struct mmu_desc {
+ unsigned int num_levels;
+ unsigned int pgtbl_count;
+ pte_t *next_pgtbl;
+ pte_t *pgtbl_base;
+};
+
+extern unsigned char cpu0_boot_stack[STACK_SIZE];
+
+#define PHYS_OFFSET ((unsigned long)_start - XEN_VIRT_START)
+#define LOAD_TO_LINK(addr) ((addr) - PHYS_OFFSET)
+#define LINK_TO_LOAD(addr) ((addr) + PHYS_OFFSET)
+
+/*
+ * It is expected that Xen won't be more then 2 MB.
+ * The check in xen.lds.S guarantees that.
+ * At least 3 page tables (in case of Sv39 ) are needed to cover 2 MB.
+ * One for each page level table with PAGE_SIZE = 4 Kb.
+ *
+ * One L0 page table can cover 2 MB(512 entries of one page table * PAGE_SIZE).
+ *
+ * It might be needed one more page table in case when Xen load address
+ * isn't 2 MB aligned.
+ */
+#define PGTBL_INITIAL_COUNT ((CONFIG_PAGING_LEVELS - 1) + 1)
+
+pte_t __section(".bss.page_aligned") __aligned(PAGE_SIZE)
+stage1_pgtbl_root[PAGETABLE_ENTRIES];
+
+pte_t __section(".bss.page_aligned") __aligned(PAGE_SIZE)
+stage1_pgtbl_nonroot[PGTBL_INITIAL_COUNT * PAGETABLE_ENTRIES];
+
+#define HANDLE_PGTBL(curr_lvl_num) \
+ index = pt_index(curr_lvl_num, page_addr); \
+ if ( pte_is_valid(pgtbl[index]) ) \
+ { \
+ /* Find L{ 0-3 } table */ \
+ pgtbl = (pte_t *)pte_to_paddr(pgtbl[index]); \
+ } \
+ else \
+ { \
+ /* Allocate new L{0-3} page table */ \
+ if ( mmu_desc->pgtbl_count == PGTBL_INITIAL_COUNT ) \
+ { \
+ early_printk("(XEN) No initial table available\n"); \
+ /* panic(), BUG() or ASSERT() aren't ready now. */ \
+ die(); \
+ } \
+ mmu_desc->pgtbl_count++; \
+ pgtbl[index] = paddr_to_pte((unsigned long)mmu_desc->next_pgtbl, \
+ PTE_VALID); \
+ pgtbl = mmu_desc->next_pgtbl; \
+ mmu_desc->next_pgtbl += PAGETABLE_ENTRIES; \
+ }
+
+static void __init setup_initial_mapping(struct mmu_desc *mmu_desc,
+ unsigned long map_start,
+ unsigned long map_end,
+ unsigned long pa_start)
+{
+ unsigned int index;
+ pte_t *pgtbl;
+ unsigned long page_addr;
+
+ if ( (unsigned long)_start % XEN_PT_LEVEL_SIZE(0) )
+ {
+ early_printk("(XEN) Xen should be loaded at 4k boundary\n");
+ die();
+ }
+
+ if ( (map_start & ~XEN_PT_LEVEL_MAP_MASK(0)) ||
+ (pa_start & ~XEN_PT_LEVEL_MAP_MASK(0)) )
+ {
+ early_printk("(XEN) map and pa start addresses should be aligned\n");
+ /* panic(), BUG() or ASSERT() aren't ready now. */
+ die();
+ }
+
+ for ( page_addr = map_start;
+ page_addr < map_end;
+ page_addr += XEN_PT_LEVEL_SIZE(0) )
+ {
+ pgtbl = mmu_desc->pgtbl_base;
+
+ switch ( mmu_desc->num_levels )
+ {
+ case 4: /* Level 3 */
+ HANDLE_PGTBL(3);
+ case 3: /* Level 2 */
+ HANDLE_PGTBL(2);
+ case 2: /* Level 1 */
+ HANDLE_PGTBL(1);
+ case 1: /* Level 0 */
+ {
+ unsigned long paddr = (page_addr - map_start) + pa_start;
+ unsigned int permissions = PTE_LEAF_DEFAULT;
+ pte_t pte_to_be_written;
+
+ index = pt_index(0, page_addr);
+
+ if ( is_kernel_text(LINK_TO_LOAD(page_addr)) ||
+ is_kernel_inittext(LINK_TO_LOAD(page_addr)) )
+ permissions =
+ PTE_EXECUTABLE | PTE_READABLE | PTE_VALID;
+
+ if ( is_kernel_rodata(LINK_TO_LOAD(page_addr)) )
+ permissions = PTE_READABLE | PTE_VALID;
+
+ pte_to_be_written = paddr_to_pte(paddr, permissions);
+
+ if ( !pte_is_valid(pgtbl[index]) )
+ pgtbl[index] = pte_to_be_written;
+ else
+ {
+ if ( (pgtbl[index].pte ^ pte_to_be_written.pte) &
+ ~(PTE_DIRTY | PTE_ACCESSED) )
+ {
+ early_printk("PTE overridden has occurred\n");
+ /* panic(), <asm/bug.h> aren't ready now. */
+ die();
+ }
+ }
+ }
+ }
+ }
+}
+#undef HANDLE_PGTBL
+
+static bool __init check_pgtbl_mode_support(struct mmu_desc *mmu_desc,
+ unsigned long load_start)
+{
+ bool is_mode_supported = false;
+ unsigned int index;
+ unsigned int page_table_level = (mmu_desc->num_levels - 1);
+ unsigned level_map_mask = XEN_PT_LEVEL_MAP_MASK(page_table_level);
+
+ unsigned long aligned_load_start = load_start & level_map_mask;
+ unsigned long aligned_page_size = XEN_PT_LEVEL_SIZE(page_table_level);
+ unsigned long xen_size = (unsigned long)(_end - start);
+
+ if ( (load_start + xen_size) > (aligned_load_start + aligned_page_size) )
+ {
+ early_printk("please place Xen to be in range of PAGE_SIZE "
+ "where PAGE_SIZE is XEN_PT_LEVEL_SIZE( {L3 | L2 | L1} ) "
+ "depending on expected SATP_MODE \n"
+ "XEN_PT_LEVEL_SIZE is defined in <asm/page.h>\n");
+ die();
+ }
+
+ index = pt_index(page_table_level, aligned_load_start);
+ stage1_pgtbl_root[index] = paddr_to_pte(aligned_load_start,
+ PTE_LEAF_DEFAULT | PTE_EXECUTABLE);
+
+ sfence_vma();
+ csr_write(CSR_SATP,
+ PFN_DOWN((unsigned long)stage1_pgtbl_root) |
+ RV_STAGE1_MODE << SATP_MODE_SHIFT);
+
+ if ( (csr_read(CSR_SATP) >> SATP_MODE_SHIFT) == RV_STAGE1_MODE )
+ is_mode_supported = true;
+
+ csr_write(CSR_SATP, 0);
+
+ sfence_vma();
+
+ /* Clean MMU root page table */
+ stage1_pgtbl_root[index] = paddr_to_pte(0x0, 0x0);
+
+ return is_mode_supported;
+}
+
+/*
+ * setup_initial_pagetables:
+ *
+ * Build the page tables for Xen that map the following:
+ * 1. Calculate page table's level numbers.
+ * 2. Init mmu description structure.
+ * 3. Check that linker addresses range doesn't overlap
+ * with load addresses range
+ * 4. Map all linker addresses and load addresses ( it shouldn't
+ * be 1:1 mapped and will be 1:1 mapped only in case if
+ * linker address is equal to load address ) with
+ * RW permissions by default.
+ * 5. Setup proper PTE permissions for each section.
+ */
+void __init setup_initial_pagetables(void)
+{
+ struct mmu_desc mmu_desc = { CONFIG_PAGING_LEVELS, 0, NULL, NULL };
+
+ /*
+ * Access to _start, _end is always PC-relative thereby when access
+ * them we will get load adresses of start and end of Xen.
+ * To get linker addresses LOAD_TO_LINK() is required to use.
+ */
+ unsigned long load_start = (unsigned long)_start;
+ unsigned long load_end = (unsigned long)_end;
+ unsigned long linker_start = LOAD_TO_LINK(load_start);
+ unsigned long linker_end = LOAD_TO_LINK(load_end);
+
+ if ( (linker_start != load_start) &&
+ (linker_start <= load_end) && (load_start <= linker_end) )
+ {
+ early_printk("(XEN) linker and load address ranges overlap\n");
+ die();
+ }
+
+ if ( !check_pgtbl_mode_support(&mmu_desc, load_start) )
+ {
+ early_printk("requested MMU mode isn't supported by CPU\n"
+ "Please choose different in <asm/config.h>\n");
+ die();
+ }
+
+ mmu_desc.pgtbl_base = stage1_pgtbl_root;
+ mmu_desc.next_pgtbl = stage1_pgtbl_nonroot;
+
+ setup_initial_mapping(&mmu_desc,
+ linker_start,
+ linker_end,
+ load_start);
+}
+
+void __init noreturn noinline enable_mmu()
+{
+ /*
+ * Calculate a linker time address of the mmu_is_enabled
+ * label and update CSR_STVEC with it.
+ * MMU is configured in a way where linker addresses are mapped
+ * on load addresses so in a case when linker addresses are not equal
+ * to load addresses, after MMU is enabled, it will cause
+ * an exception and jump to linker time addresses.
+ * Otherwise if load addresses are equal to linker addresses the code
+ * after mmu_is_enabled label will be executed without exception.
+ */
+ csr_write(CSR_STVEC, LOAD_TO_LINK((unsigned long)&&mmu_is_enabled));
+
+ /* Ensure page table writes precede loading the SATP */
+ sfence_vma();
+
+ /* Enable the MMU and load the new pagetable for Xen */
+ csr_write(CSR_SATP,
+ PFN_DOWN((unsigned long)stage1_pgtbl_root) |
+ RV_STAGE1_MODE << SATP_MODE_SHIFT);
+
+ asm volatile ( ".p2align 2" );
+ mmu_is_enabled:
+ /*
+ * Stack should be re-inited as:
+ * 1. Right now an address of the stack is relative to load time
+ * addresses what will cause an issue in case of load start address
+ * isn't equal to linker start address.
+ * 2. Addresses in stack are all load time relative which can be an
+ * issue in case when load start address isn't equal to linker
+ * start address.
+ *
+ * We can't return to the caller because the stack was reseted
+ * and it may have stash some variable on the stack.
+ * Jump to a brand new function as the stack was reseted
+ */
+
+ switch_stack_and_jump((unsigned long)cpu0_boot_stack + STACK_SIZE,
+ cont_after_mmu_is_enabled);
+}
diff --git a/xen/arch/riscv/setup.c b/xen/arch/riscv/setup.c
index 3786f337e0..315804aa87 100644
--- a/xen/arch/riscv/setup.c
+++ b/xen/arch/riscv/setup.c
@@ -2,6 +2,7 @@
#include <xen/init.h>
#include <asm/early_printk.h>
+#include <asm/mm.h>
/* Xen stack for bringing up the first CPU. */
unsigned char __initdata cpu0_boot_stack[STACK_SIZE]
@@ -26,3 +27,13 @@ void __init noreturn start_xen(unsigned long bootcpu_id,
unreachable();
}
+
+void __init noreturn cont_after_mmu_is_enabled(void)
+{
+ early_printk("All set up\n");
+
+ for ( ;; )
+ asm volatile ("wfi");
+
+ unreachable();
+}
diff --git a/xen/arch/riscv/xen.lds.S b/xen/arch/riscv/xen.lds.S
index 31e0d3576c..3e80d6632f 100644
--- a/xen/arch/riscv/xen.lds.S
+++ b/xen/arch/riscv/xen.lds.S
@@ -172,3 +172,5 @@ ASSERT(IS_ALIGNED(__bss_end, POINTER_ALIGN),
"__bss_end is misaligned")
ASSERT(!SIZEOF(.got), ".got non-empty")
ASSERT(!SIZEOF(.got.plt), ".got.plt non-empty")
+
+ASSERT(_end - _start <= MB(2), "Xen too large for early-boot assumptions")
--
generated by git-patchbot for /home/xen/git/xen.git#master
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