[PATCH v1 04/12] xen/hvmlite: Bootstrap HVMlite guest

[Boris Ostrovsky]

Start HVMlite guest XEN_ELFNOTE_PHYS32_ENTRY address. Setup hypercall
page, initialize boot_params, enable early page tables.

Signed-off-by: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
---
 arch/x86/xen/Makefile      |    1 +
 arch/x86/xen/enlighten.c   |   91 +++++++++++++++++++++++++-
 arch/x86/xen/xen-hvmlite.S |  158 ++++++++++++++++++++++++++++++++++++++++++++
 include/xen/xen.h          |    6 ++
 4 files changed, 255 insertions(+), 1 deletions(-)
 create mode 100644 arch/x86/xen/xen-hvmlite.S

diff --git a/arch/x86/xen/Makefile b/arch/x86/xen/Makefile
index e47e527..1d913d7 100644
--- a/arch/x86/xen/Makefile
+++ b/arch/x86/xen/Makefile
@@ -23,3 +23,4 @@ obj-$(CONFIG_XEN_DEBUG_FS)	+= debugfs.o
 obj-$(CONFIG_XEN_DOM0)		+= vga.o
 obj-$(CONFIG_SWIOTLB_XEN)	+= pci-swiotlb-xen.o
 obj-$(CONFIG_XEN_EFI)		+= efi.o
+obj-$(CONFIG_XEN_PVHVM) 	+= xen-hvmlite.o
diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index 2cf446a..2ed8b2b 100644
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -118,7 +118,8 @@ DEFINE_PER_CPU(struct vcpu_info *, xen_vcpu);
  */
 DEFINE_PER_CPU(struct vcpu_info, xen_vcpu_info);
 
-enum xen_domain_type xen_domain_type = XEN_NATIVE;
+enum xen_domain_type xen_domain_type
+	__attribute__((section(".data"))) = XEN_NATIVE;
 EXPORT_SYMBOL_GPL(xen_domain_type);
 
 unsigned long *machine_to_phys_mapping = (void *)MACH2PHYS_VIRT_START;
@@ -171,6 +172,17 @@ struct tls_descs {
  */
 static DEFINE_PER_CPU(struct tls_descs, shadow_tls_desc);
 
+#ifdef CONFIG_XEN_PVHVM
+/*
+ * HVMlite variables. These need to live in data segment since they are
+ * initialized before startup_{32|64}, which clear .bss, are invoked.
+ */
+int xen_hvmlite __attribute__((section(".data"))) = 0;
+struct hvm_start_info hvmlite_start_info __attribute__((section(".data")));
+uint hvmlite_start_info_sz = sizeof(hvmlite_start_info);
+struct boot_params xen_hvmlite_boot_params __attribute__((section(".data")));
+#endif
+
 static void clamp_max_cpus(void)
 {
 #ifdef CONFIG_SMP
@@ -1736,6 +1748,83 @@ asmlinkage __visible void __init xen_start_kernel(void)
 #endif
 }
 
+#ifdef CONFIG_XEN_PVHVM
+static void __init hvmlite_bootparams(void)
+{
+	struct xen_memory_map memmap;
+	int i;
+
+	memset(&xen_hvmlite_boot_params, 0, sizeof(xen_hvmlite_boot_params));
+
+	memmap.nr_entries = ARRAY_SIZE(xen_hvmlite_boot_params.e820_map);
+	set_xen_guest_handle(memmap.buffer, xen_hvmlite_boot_params.e820_map);
+	if (HYPERVISOR_memory_op(XENMEM_memory_map, &memmap)) {
+		xen_raw_console_write("XENMEM_memory_map failed\n");
+		BUG();
+	}
+
+	xen_hvmlite_boot_params.e820_map[memmap.nr_entries].addr =
+		ISA_START_ADDRESS;
+	xen_hvmlite_boot_params.e820_map[memmap.nr_entries].size =
+		ISA_END_ADDRESS - ISA_START_ADDRESS;
+	xen_hvmlite_boot_params.e820_map[memmap.nr_entries++].type =
+		E820_RESERVED;
+
+	sanitize_e820_map(xen_hvmlite_boot_params.e820_map,
+			  ARRAY_SIZE(xen_hvmlite_boot_params.e820_map),
+			  &memmap.nr_entries);
+
+	xen_hvmlite_boot_params.e820_entries = memmap.nr_entries;
+	for (i = 0; i < xen_hvmlite_boot_params.e820_entries; i++)
+		e820_add_region(xen_hvmlite_boot_params.e820_map[i].addr,
+				xen_hvmlite_boot_params.e820_map[i].size,
+				xen_hvmlite_boot_params.e820_map[i].type);
+
+	xen_hvmlite_boot_params.hdr.cmd_line_ptr =
+		hvmlite_start_info.cmdline_paddr;
+
+	/* The first module is always ramdisk */
+	if (hvmlite_start_info.nr_modules) {
+		struct hvm_modlist_entry *modaddr =
+			__va(hvmlite_start_info.modlist_paddr);
+		xen_hvmlite_boot_params.hdr.ramdisk_image = modaddr->paddr;
+		xen_hvmlite_boot_params.hdr.ramdisk_size = modaddr->size;
+	}
+
+	/*
+	 * See Documentation/x86/boot.txt.
+	 *
+	 * Version 2.12 supports Xen entry point but we will use default x86/PC
+	 * environment (i.e. hardware_subarch 0).
+	 */
+	xen_hvmlite_boot_params.hdr.version = 0x212;
+	xen_hvmlite_boot_params.hdr.type_of_loader = 9; /* Xen loader */
+}
+
+/*
+ * This routine (and those that it might call) should not use
+ * anything that lives in .bss since that segment will be cleared later
+ */
+void __init xen_prepare_hvmlite(void)
+{
+	u32 eax, ecx, edx, msr;
+	u64 pfn;
+
+	cpuid(xen_cpuid_base() + 2, &eax, &msr, &ecx, &edx);
+	pfn = __pa(hypercall_page);
+	wrmsr_safe(msr, (u32)pfn, (u32)(pfn >> 32));
+
+	pv_info.name = "Xen HVMlite";
+	xen_domain_type = XEN_HVM_DOMAIN;
+	xen_hvmlite = 1;
+
+	x86_init.oem.arch_setup = xen_init_kernel;
+	x86_init.oem.banner = xen_banner;
+
+	hvmlite_bootparams();
+}
+#endif
+
 void __ref xen_hvm_init_shared_info(void)
 {
 	int cpu;
diff --git a/arch/x86/xen/xen-hvmlite.S b/arch/x86/xen/xen-hvmlite.S
new file mode 100644
index 0000000..90f03d0
--- /dev/null
+++ b/arch/x86/xen/xen-hvmlite.S
@@ -0,0 +1,158 @@
+/*
+ * Copyright C 2016, Oracle and/or its affiliates. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+	.code32
+	.text
+#define _pa(x)          ((x) - __START_KERNEL_map)
+
+#include <linux/elfnote.h>
+#include <linux/init.h>
+#include <linux/linkage.h>
+#include <asm/segment.h>
+#include <asm/asm.h>
+#include <asm/boot.h>
+#include <asm/processor-flags.h>
+#include <asm/msr.h>
+#include <xen/interface/elfnote.h>
+
+	__HEAD
+	.code32
+
+/* Entry point for HVMlite guests */
+ENTRY(hvmlite_start_xen)
+	cli
+	cld
+
+	mov $_pa(gdt), %eax
+	lgdt (%eax)
+
+	movl $(__BOOT_DS),%eax
+	movl %eax,%ds
+	movl %eax,%es
+	movl %eax,%ss
+
+	/* Stash hvm_start_info */
+	mov $_pa(hvmlite_start_info), %edi
+	mov %ebx, %esi
+	mov $_pa(hvmlite_start_info_sz), %ecx
+	mov (%ecx), %ecx
+	rep
+	movsb
+
+	movl $_pa(early_stack_end), %eax
+	movl %eax, %esp
+
+	/* Enable PAE mode */
+	movl %cr4, %eax
+	orl $X86_CR4_PAE, %eax
+	movl %eax, %cr4
+
+#ifdef CONFIG_X86_64
+	/* Enable Long mode */
+	movl $MSR_EFER, %ecx
+	rdmsr
+	btsl $_EFER_LME, %eax
+	wrmsr
+
+	/* Enable pre-constructed page tables */
+	mov $_pa(init_level4_pgt), %eax
+	movl %eax, %cr3
+	movl $(X86_CR0_PG | X86_CR0_PE), %eax
+	movl %eax, %cr0
+
+	/* Jump to 64-bit mode. */
+	pushl $__KERNEL_CS
+	leal _pa(1f), %eax
+	pushl %eax
+	lret
+
+	/* 64-bit entry point */
+	.code64
+1:
+	call xen_prepare_hvmlite
+
+	/* startup_64 expects boot_params in %rsi */
+	mov $_pa(xen_hvmlite_boot_params), %rsi
+	movq $_pa(startup_64), %rax
+	jmp *%rax
+
+#else /* CONFIG_X86_64 */
+
+	/* Use initial_page table and set level 2 to map 2M pages */
+	movl $_pa(initial_pg_pmd), %edi
+	movl $(_PAGE_PSE | _PAGE_RW | _PAGE_PRESENT), %eax
+	movl $2048, %ecx
+2:
+	movl %eax, 0(%edi)
+	addl $0x00200000, %eax
+	addl $8, %edi
+	decl %ecx
+	jnz 2b
+
+	/* Enable the boot paging */
+	movl $_pa(initial_page_table), %eax
+	movl %eax, %cr3
+	movl %cr0, %eax
+	orl $(X86_CR0_PG | X86_CR0_PE), %eax
+	movl %eax, %cr0
+
+	ljmp $__BOOT_CS,$3f
+3:
+	call xen_prepare_hvmlite
+	mov $_pa(xen_hvmlite_boot_params), %esi
+
+	/* startup_32 doesn't expect paging and PAE to be on */
+	ljmp $__BOOT_CS,$_pa(4f)
+4:
+	movl %cr0, %eax
+	andl $~X86_CR0_PG, %eax
+	movl %eax, %cr0
+	movl %cr4, %eax
+	andl $~X86_CR4_PAE, %eax
+	movl %eax, %cr4
+
+	/* Restore initial_pg_pmd to its original (zero) state */
+	movl $_pa(initial_pg_pmd), %edi
+	xorl %eax, %eax
+	movl $(PAGE_SIZE/4), %ecx
+	rep stosl
+
+	ljmp    $0x10, $_pa(startup_32)
+#endif
+
+	.data
+gdt:
+	.word	gdt_end - gdt
+	.long	_pa(gdt)
+	.word	0
+	.quad	0x0000000000000000 /* NULL descriptor */
+#ifdef CONFIG_X86_64
+	.quad	0x00af9a000000ffff /* __KERNEL_CS */
+#else
+	.quad	0x00cf9a000000ffff /* __KERNEL_CS */
+#endif
+	.quad	0x00cf92000000ffff /* __KERNEL_DS */
+gdt_end:
+
+	.bss
+	.balign 4
+early_stack:
+	.fill 16, 1, 0
+early_stack_end:
+
+	ELFNOTE(Xen, XEN_ELFNOTE_PHYS32_ENTRY,
+	             _ASM_PTR (hvmlite_start_xen - __START_KERNEL_map))
diff --git a/include/xen/xen.h b/include/xen/xen.h
index 0c0e3ef..6a0d3f3 100644
--- a/include/xen/xen.h
+++ b/include/xen/xen.h
@@ -29,6 +29,12 @@ extern enum xen_domain_type xen_domain_type;
 #define xen_initial_domain()	(0)
 #endif	/* CONFIG_XEN_DOM0 */
 
+#ifdef CONFIG_XEN_PVHVM
+extern int xen_hvmlite;
+#else
+#define xen_hvmlite		(0)
+#endif
+
 #ifdef CONFIG_XEN_PVH
 /* This functionality exists only for x86. The XEN_PVHVM support exists
  * only in x86 world - hence on ARM it will be always disabled.
-- 
1.7.1