first commit

Based on x86/bios from lkvm

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 70 insertions, 0 deletions

diff --git a/e820.c b/e820.c
new file mode 100644
index 0000000..4eab157
--- /dev/null
+++ b/e820.c
@@ -0,0 +1,70 @@
+#include "bios.h"
+#include "segment.h"
+
+#include "processor-flags.h"
+#include "e820.h"
+
+static inline void set_fs(uint16_t seg)
+{
+	asm volatile("movw %0,%%fs" : : "rm" (seg));
+}
+
+static inline uint8_t rdfs8(unsigned long addr)
+{
+	uint8_t v;
+
+	asm volatile("addr32 movb %%fs:%1,%0" : "=q" (v) : "m" (*(uint8_t *)addr));
+
+	return v;
+}
+
+static inline uint32_t rdfs32(unsigned long addr)
+{
+	uint32_t v;
+
+	asm volatile("addr32 movl %%fs:%1,%0" : "=q" (v) : "m" (*(uint32_t *)addr));
+
+	return v;
+}
+
+bioscall void e820_query_map(struct biosregs *regs)
+{
+	struct e820map *e820;
+	uint32_t map_size;
+	uint16_t fs_seg;
+	uint32_t ndx;
+
+	e820		= (struct e820map *)E820_MAP_START;
+	fs_seg		= flat_to_seg16(E820_MAP_START);
+	set_fs(fs_seg);
+
+	ndx		= regs->ebx;
+
+	map_size	= rdfs32(flat_to_off16((uint32_t)&e820->nr_map, fs_seg));
+
+	if (ndx < map_size) {
+		uint32_t start;
+		unsigned int i;
+		uint8_t *p;
+
+		fs_seg	= flat_to_seg16(E820_MAP_START);
+		set_fs(fs_seg);
+
+		start	= (uint32_t)&e820->map[ndx];
+
+		p	= (void *) regs->edi;
+
+		for (i = 0; i < sizeof(struct e820entry); i++)
+			*p++	= rdfs8(flat_to_off16(start + i, fs_seg));
+	}
+
+	regs->eax	= SMAP;
+	regs->ecx	= sizeof(struct e820entry);
+	regs->ebx	= ++ndx;
+
+	/* Clear CF to indicate success.  */
+	regs->eflags	&= ~X86_EFLAGS_CF;
+
+	if (ndx >= map_size)
+		regs->ebx	= 0;	/* end of map */
+}