[PATCH v1 5/6] xen/riscv: implement relocate_fdt()

[Oleksii Kurochko <oleksii.kurochko@xxxxxxxxx>]

relocate_fdt() relocates FDT to Xen heap instead of using early mapping
as it is expected that discard_initial_modules() ( is supposed to call
in the future ) discards the FDT boot module and remove_early_mappings()
destroys the early mapping.

To implement that the following things are introduced as they are called
by internals of xmalloc_bytes() which is used in relocate_fdt():
1. As RISC-V may have non-coherent access for RAM ( f.e., in case
   of non-coherent IO devices ) flush_page_to_ram() is implemented
   to ensure that cache and RAM are consistent for such platforms.
2. copy_from_paddr() to copy FDT from a physical address to allocated
   by xmalloc_bytes() in Xen heap.
3. virt_to_page() to convert virtual address to page. Also introduce
   directmap_virt_end to check that VA argument of virt_to_page() is
   inside directmap region.

Signed-off-by: Oleksii Kurochko <oleksii.kurochko@xxxxxxxxx>
---
 xen/arch/riscv/include/asm/mm.h   | 10 ++++++--
 xen/arch/riscv/include/asm/page.h | 10 ++++++--
 xen/arch/riscv/mm.c               |  3 +++
 xen/arch/riscv/setup.c            | 41 +++++++++++++++++++++++++++++++
 4 files changed, 60 insertions(+), 4 deletions(-)

diff --git a/xen/arch/riscv/include/asm/mm.h b/xen/arch/riscv/include/asm/mm.h
index 699ed23f0d..25fd38531f 100644
--- a/xen/arch/riscv/include/asm/mm.h
+++ b/xen/arch/riscv/include/asm/mm.h
@@ -8,11 +8,13 @@
 #include <xen/const.h>
 #include <xen/mm-frame.h>
 #include <xen/pdx.h>
+#include <xen/pfn.h>
 #include <xen/types.h>
 
 #include <asm/page-bits.h>
 
 extern vaddr_t directmap_virt_start;
+extern vaddr_t directmap_virt_end;
 
 #define pfn_to_paddr(pfn) ((paddr_t)(pfn) << PAGE_SHIFT)
 #define paddr_to_pfn(pa)  ((unsigned long)((pa) >> PAGE_SHIFT))
@@ -148,8 +150,12 @@ static inline void *page_to_virt(const struct page_info 
*pg)
 /* Convert between Xen-heap virtual addresses and page-info structures. */
 static inline struct page_info *virt_to_page(const void *v)
 {
-    BUG_ON("unimplemented");
-    return NULL;
+    unsigned long va = (unsigned long)v;
+
+    ASSERT(va >= DIRECTMAP_VIRT_START);
+    ASSERT(va <= directmap_virt_end);
+
+    return frametable_virt_start + PFN_DOWN(va - directmap_virt_start);
 }
 
 /*
diff --git a/xen/arch/riscv/include/asm/page.h 
b/xen/arch/riscv/include/asm/page.h
index 0f297141d3..c245a4273f 100644
--- a/xen/arch/riscv/include/asm/page.h
+++ b/xen/arch/riscv/include/asm/page.h
@@ -7,6 +7,7 @@
 
 #include <xen/bug.h>
 #include <xen/const.h>
+#include <xen/domain_page.h>
 #include <xen/errno.h>
 #include <xen/types.h>
 
@@ -172,10 +173,15 @@ static inline void invalidate_icache(void)
 #define clear_page(page) memset((void *)(page), 0, PAGE_SIZE)
 #define copy_page(dp, sp) memcpy(dp, sp, PAGE_SIZE)
 
-/* TODO: Flush the dcache for an entire page. */
 static inline void flush_page_to_ram(unsigned long mfn, bool sync_icache)
 {
-    BUG_ON("unimplemented");
+    void *v = map_domain_page(_mfn(mfn));
+
+    clean_and_invalidate_dcache_va_range(v, PAGE_SIZE);
+    unmap_domain_page(v);
+
+    if ( sync_icache )
+        invalidate_icache();
 }
 
 /* Write a pagetable entry. */
diff --git a/xen/arch/riscv/mm.c b/xen/arch/riscv/mm.c
index f2bf279bac..c614d547a6 100644
--- a/xen/arch/riscv/mm.c
+++ b/xen/arch/riscv/mm.c
@@ -419,6 +419,7 @@ void * __init early_fdt_map(paddr_t fdt_paddr)
 }
 
 vaddr_t __ro_after_init directmap_virt_start = DIRECTMAP_VIRT_START;
+vaddr_t __ro_after_init directmap_virt_end;
 
 struct page_info *__ro_after_init frametable_virt_start = frame_table;
 
@@ -556,6 +557,8 @@ void __init setup_mm(void)
         setup_directmap_mappings(PFN_DOWN(bank_start), PFN_DOWN(bank_size));
     }
 
+    directmap_virt_end = directmap_virt_start + ram_end - 1;
+
     setup_frametable_mappings(ram_start, ram_end);
     max_page = PFN_DOWN(ram_end);
 }
diff --git a/xen/arch/riscv/setup.c b/xen/arch/riscv/setup.c
index 9680332fee..ff667260ec 100644
--- a/xen/arch/riscv/setup.c
+++ b/xen/arch/riscv/setup.c
@@ -12,6 +12,7 @@
 #include <public/version.h>
 
 #include <asm/early_printk.h>
+#include <asm/fixmap.h>
 #include <asm/sbi.h>
 #include <asm/setup.h>
 #include <asm/smp.h>
@@ -26,6 +27,46 @@ void arch_get_xen_caps(xen_capabilities_info_t *info)
 unsigned char __initdata cpu0_boot_stack[STACK_SIZE]
     __aligned(STACK_SIZE);
 
+/**
+ * copy_from_paddr - copy data from a physical address
+ * @dst: destination virtual address
+ * @paddr: source physical address
+ * @len: length to copy
+ */
+void __init copy_from_paddr(void *dst, paddr_t paddr, unsigned long len)
+{
+    void *src = (void *)FIXMAP_ADDR(FIX_MISC);
+
+    while (len) {
+        unsigned long l, s;
+
+        s = paddr & (PAGE_SIZE - 1);
+        l = min(PAGE_SIZE - s, len);
+
+        set_fixmap(FIX_MISC, maddr_to_mfn(paddr), PAGE_HYPERVISOR_RW);
+        memcpy(dst, src + s, l);
+        clean_dcache_va_range(dst, l);
+        clear_fixmap(FIX_MISC);
+
+        paddr += l;
+        dst += l;
+        len -= l;
+    }
+}
+
+/* Relocate the FDT in Xen heap */
+static void * __init relocate_fdt(paddr_t dtb_paddr, size_t dtb_size)
+{
+    void *fdt = xmalloc_bytes(dtb_size);
+
+    if ( !fdt )
+        panic("Unable to allocate memory for relocating the Device-Tree.\n");
+
+    copy_from_paddr(fdt, dtb_paddr, dtb_size);
+
+    return fdt;
+}
+
 void __init noreturn start_xen(unsigned long bootcpu_id,
                                paddr_t dtb_addr)
 {
-- 
2.47.0