[PATCH 4/4] kexec/xen: directly load images images into Xen

[David Vrabel <david.vrabel@citrix.com>]

From: David Vrabel <david.vrabel@citrix.com>

Xen 4.3 has an improvided kexec hypercall ABI that allows images to be
loaded and executed without any kernel involvement.  Use the API
provided by libxc to load images when running in a Xen guest.

Support for loading images via the kexec_load syscall in non-upstream
("classic") Xen kernels is no longer supported.

Signed-off-by: David Vrabel <david.vrabel@citrix.com>
---
 kexec/Makefile                     |    1 +
 kexec/arch/i386/crashdump-x86.c    |   19 ++++++++-
 kexec/arch/i386/kexec-x86-common.c |    6 +-
 kexec/crashdump-xen.c              |   34 ++++++++++++++++
 kexec/crashdump.h                  |    3 +-
 kexec/kexec-xen.c                  |   76 ++++++++++++++++++++++++++++++++++++
 kexec/kexec.c                      |   10 ++++-
 kexec/kexec.h                      |    5 ++
 8 files changed, 147 insertions(+), 7 deletions(-)
 create mode 100644 kexec/kexec-xen.c

diff --git a/kexec/Makefile b/kexec/Makefile
index 8a6138d..dc9dab1 100644
--- a/kexec/Makefile
+++ b/kexec/Makefile
@@ -25,6 +25,7 @@ KEXEC_SRCS_base += kexec/phys_arch.c
 KEXEC_SRCS_base += kexec/kernel_version.c
 KEXEC_SRCS_base += kexec/lzma.c
 KEXEC_SRCS_base += kexec/zlib.c
+KEXEC_SRCS_base += kexec/kexec-xen.c
 
 KEXEC_GENERATED_SRCS += $(PURGATORY_HEX_C)
 
diff --git a/kexec/arch/i386/crashdump-x86.c b/kexec/arch/i386/crashdump-x86.c
index f9709fe..46a76f9 100644
--- a/kexec/arch/i386/crashdump-x86.c
+++ b/kexec/arch/i386/crashdump-x86.c
@@ -939,11 +939,28 @@ int load_crashdump_segments(struct kexec_info *info, char* mod_cmdline,
 	return 0;
 }
 
+int get_crashkernel_region(uint64_t *start, uint64_t *end)
+{
+	int ret;
+
+	if (xen_present())
+		ret = xen_get_crashkernel_region(start, end);
+	else
+		ret = parse_iomem_single("Crash kernel\n", start, end);
+	if (ret < 0)
+		return ret;
+	if (start == end)
+		return -1;
+	return 0;
+}
+
 int is_crashkernel_mem_reserved(void)
 {
 	uint64_t start, end;
+	int rc;
 
-	if (parse_iomem_single("Crash kernel\n", &start, &end) || start == end)
+	rc = get_crashkernel_region(&start, &end);
+	if (rc < 0)
 		return 0;
 
 	crash_reserved_mem.start = start;
diff --git a/kexec/arch/i386/kexec-x86-common.c b/kexec/arch/i386/kexec-x86-common.c
index dba89f2..2477dee 100644
--- a/kexec/arch/i386/kexec-x86-common.c
+++ b/kexec/arch/i386/kexec-x86-common.c
@@ -364,9 +364,9 @@ int get_memory_ranges(struct memory_range **range, int *ranges,
 	    !(kexec_flags & KEXEC_PRESERVE_CONTEXT)) {
 		uint64_t start, end;
 
-		ret = parse_iomem_single("Crash kernel\n", &start, &end);
-		if (ret != 0) {
-			fprintf(stderr, "parse_iomem_single failed.\n");
+		ret = get_crashkernel_region(&start, &end);
+		if (ret < 0) {
+			fprintf(stderr, "No crash region available.\n");
 			return -1;
 		}
 
diff --git a/kexec/crashdump-xen.c b/kexec/crashdump-xen.c
index 13335a5..434fe66 100644
--- a/kexec/crashdump-xen.c
+++ b/kexec/crashdump-xen.c
@@ -223,3 +223,37 @@ int xen_get_note(int cpu, uint64_t *addr, uint64_t *len)
 
 	return 0;
 }
+
+#ifdef HAVE_LIBXENCTRL
+int xen_get_crashkernel_region(uint64_t *start, uint64_t *end)
+{
+	uint64_t size;
+	xc_interface *xc;
+	int rc = -1;
+
+	xc = xc_interface_open(NULL, NULL, 0);
+	if (!xc) {
+		fprintf(stderr, "failed to open xen control interface.\n");
+		goto out;
+	}
+
+	rc = xc_kexec_get_range(xc, KEXEC_RANGE_MA_CRASH, 0, &size, start);
+	if (rc < 0) {
+		fprintf(stderr, "failed to get crash region from hypervisor.\n");
+		goto out_close;
+	}
+
+	*end = *start + size - 1;
+
+out_close:
+	xc_interface_close(xc);
+
+out:
+	return rc;
+}
+#else
+int xen_get_crashkernel_region(uint64_t *start, uint64_t *end)
+{
+	return -1;
+}
+#endif
diff --git a/kexec/crashdump.h b/kexec/crashdump.h
index 0f7c2ea..95f1f0c 100644
--- a/kexec/crashdump.h
+++ b/kexec/crashdump.h
@@ -1,6 +1,7 @@
 #ifndef CRASHDUMP_H
 #define CRASHDUMP_H
 
+int get_crashkernel_region(uint64_t *start, uint64_t *end);
 extern int get_crash_notes_per_cpu(int cpu, uint64_t *addr, uint64_t *len);
 extern int get_kernel_vmcoreinfo(uint64_t *addr, uint64_t *len);
 extern int get_xen_vmcoreinfo(uint64_t *addr, uint64_t *len);
@@ -56,9 +57,9 @@ unsigned long crash_architecture(struct crash_elf_info *elf_info);
 unsigned long phys_to_virt(struct crash_elf_info *elf_info,
 			   unsigned long paddr);
 
-int xen_present(void);
 unsigned long xen_architecture(struct crash_elf_info *elf_info);
 int xen_get_nr_phys_cpus(void);
 int xen_get_note(int cpu, uint64_t *addr, uint64_t *len);
+int xen_get_crashkernel_region(uint64_t *start, uint64_t *end);
 
 #endif /* CRASHDUMP_H */
diff --git a/kexec/kexec-xen.c b/kexec/kexec-xen.c
new file mode 100644
index 0000000..8bc16aa
--- /dev/null
+++ b/kexec/kexec-xen.c
@@ -0,0 +1,76 @@
+#define _GNU_SOURCE
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+#include "kexec.h"
+#include "crashdump.h"
+
+#include "config.h"
+
+#ifdef HAVE_LIBXENCTRL
+#include <xenctrl.h>
+
+#include "crashdump.h"
+
+int xen_kexec_load(uint64_t entry,
+		   uint32_t nr_segments, struct kexec_segment *segments,
+		   uint64_t kexec_flags)
+{
+	xc_interface *xch;
+	xc_hypercall_buffer_array_t *array = NULL;
+	uint8_t type;
+	uint8_t arch;
+	xen_kexec_segment_t *xen_segs;
+	int s;
+	int ret = -1;
+
+	xch = xc_interface_open(NULL, NULL, 0);
+	if (!xch)
+		return -1;
+
+	xen_segs = calloc(nr_segments, sizeof(*xen_segs));
+	if (!xen_segs)
+		goto out;
+
+	array = xc_hypercall_buffer_array_create(xch, nr_segments);
+	if (array == NULL)
+		goto out;
+
+	for (s = 0; s < nr_segments; s++) {
+		DECLARE_HYPERCALL_BUFFER(void, seg_buf);
+
+		seg_buf = xc_hypercall_buffer_array_alloc(xch, array, s,
+							  seg_buf, segments[s].bufsz);
+		if (seg_buf == NULL)
+			goto out;
+		memcpy(seg_buf, segments[s].buf, segments[s].bufsz);
+
+		set_xen_guest_handle(xen_segs[s].buf, seg_buf);
+		xen_segs[s].buf_size = segments[s].bufsz;
+		xen_segs[s].dest_maddr = (uint64_t)segments[s].mem;
+		xen_segs[s].dest_size = segments[s].memsz;
+	}
+
+	type = kexec_flags & KEXEC_TYPE_CRASH;
+	arch = (kexec_flags >> 16) & 0xffff;
+
+	ret = xc_kexec_load(xch, type, arch, entry, nr_segments, xen_segs);
+
+out:
+	xc_hypercall_buffer_array_destroy(xch, array);
+	free(xen_segs);
+	xc_interface_close(xch);
+
+	return ret;
+}
+
+#else /* ! HAVE_LIBXENCTRL */
+
+int xen_kexec_load(uint64_t entry,
+		   uint32_t nr_segments, struct kexec_segment *segments,
+		   uint64_t kexec_flags)
+{
+	return -1;
+}
+
+#endif
diff --git a/kexec/kexec.c b/kexec/kexec.c
index 16c6308..3eab839 100644
--- a/kexec/kexec.c
+++ b/kexec/kexec.c
@@ -764,8 +764,14 @@ static int my_load(const char *type, int fileind, int argc, char **argv,
 		info.entry, info.kexec_flags);
 	print_segments(stderr, &info);
 #endif
-	result = kexec_load(
-		info.entry, info.nr_segments, info.segment, info.kexec_flags);
+	if (xen_present())
+		result = xen_kexec_load((uint64_t)info.entry,
+					info.nr_segments, info.segment,
+					info.kexec_flags);
+	else
+		result = kexec_load(info.entry,
+				    info.nr_segments, info.segment,
+				    info.kexec_flags);
 	if (result != 0) {
 		/* The load failed, print some debugging information */
 		fprintf(stderr, "kexec_load failed: %s\n", 
diff --git a/kexec/kexec.h b/kexec/kexec.h
index 94c62c1..4ef8906 100644
--- a/kexec/kexec.h
+++ b/kexec/kexec.h
@@ -280,4 +280,9 @@ extern int add_backup_segments(struct kexec_info *info,
 
 char *concat_cmdline(const char *base, const char *append);
 
+int xen_present(void);
+int xen_kexec_load(uint64_t entry,
+		   uint32_t nr_segments, struct kexec_segment *segments,
+		   uint64_t kexec_flags);
+
 #endif /* KEXEC_H */
-- 
1.7.2.5


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