[PATCH] paravirt: header and stubs for paravirtualisation

Create a paravirt.h header for all the critical operations which need to be
replaced with hypervisor calls, and include that instead of defining native
operations, when CONFIG_PARAVIRT.

This patch does the dumbest possible replacement of paravirtualized
instructions: calls through a "paravirt_ops" structure.  Currently these are
function implementations of native hardware: hypervisors will override the ops
structure with their own variants.

All the pv-ops functions are declared "fastcall" so that a specific
register-based ABI is used, to make inlining assember easier.

And:

+From: Andy Whitcroft <apw@shadowen.org>

The paravirt ops introduce a 'weak' attribute onto memory_setup().
Code ordering leads to the following warnings on x86:

    arch/i386/kernel/setup.c:651: warning: weak declaration of
                `memory_setup' after first use results in unspecified behavior

Move memory_setup() to avoid this.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Chris Wright <chrisw@sous-sol.org>
Signed-off-by: Andi Kleen <ak@suse.de>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: Zachary Amsden <zach@vmware.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Andy Whitcroft <apw@shadowen.org>

1 files changed, 404 insertions, 0 deletions

diff --git a/arch/i386/kernel/paravirt.c b/arch/i386/kernel/paravirt.c
new file mode 100644
index 00000000000..478192cd4b9
--- /dev/null
+++ b/arch/i386/kernel/paravirt.c
@@ -0,0 +1,404 @@
+/*  Paravirtualization interfaces
+    Copyright (C) 2006 Rusty Russell IBM Corporation
+
+    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, write to the Free Software
+    Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+*/
+#include <linux/errno.h>
+#include <linux/module.h>
+#include <linux/efi.h>
+#include <linux/bcd.h>
+
+#include <asm/bug.h>
+#include <asm/paravirt.h>
+#include <asm/desc.h>
+#include <asm/setup.h>
+#include <asm/arch_hooks.h>
+#include <asm/time.h>
+#include <asm/irq.h>
+#include <asm/delay.h>
+
+/* nop stub */
+static void native_nop(void)
+{
+}
+
+static void __init default_banner(void)
+{
+	printk(KERN_INFO "Booting paravirtualized kernel on %s\n",
+	       paravirt_ops.name);
+}
+
+char *memory_setup(void)
+{
+	return paravirt_ops.memory_setup();
+}
+
+static fastcall unsigned long native_get_debugreg(int regno)
+{
+	unsigned long val = 0; 	/* Damn you, gcc! */
+
+	switch (regno) {
+	case 0:
+		asm("movl %%db0, %0" :"=r" (val)); break;
+	case 1:
+		asm("movl %%db1, %0" :"=r" (val)); break;
+	case 2:
+		asm("movl %%db2, %0" :"=r" (val)); break;
+	case 3:
+		asm("movl %%db3, %0" :"=r" (val)); break;
+	case 6:
+		asm("movl %%db6, %0" :"=r" (val)); break;
+	case 7:
+		asm("movl %%db7, %0" :"=r" (val)); break;
+	default:
+		BUG();
+	}
+	return val;
+}
+
+static fastcall void native_set_debugreg(int regno, unsigned long value)
+{
+	switch (regno) {
+	case 0:
+		asm("movl %0,%%db0"	: /* no output */ :"r" (value));
+		break;
+	case 1:
+		asm("movl %0,%%db1"	: /* no output */ :"r" (value));
+		break;
+	case 2:
+		asm("movl %0,%%db2"	: /* no output */ :"r" (value));
+		break;
+	case 3:
+		asm("movl %0,%%db3"	: /* no output */ :"r" (value));
+		break;
+	case 6:
+		asm("movl %0,%%db6"	: /* no output */ :"r" (value));
+		break;
+	case 7:
+		asm("movl %0,%%db7"	: /* no output */ :"r" (value));
+		break;
+	default:
+		BUG();
+	}
+}
+
+void init_IRQ(void)
+{
+	paravirt_ops.init_IRQ();
+}
+
+static fastcall void native_clts(void)
+{
+	asm volatile ("clts");
+}
+
+static fastcall unsigned long native_read_cr0(void)
+{
+	unsigned long val;
+	asm volatile("movl %%cr0,%0\n\t" :"=r" (val));
+	return val;
+}
+
+static fastcall void native_write_cr0(unsigned long val)
+{
+	asm volatile("movl %0,%%cr0": :"r" (val));
+}
+
+static fastcall unsigned long native_read_cr2(void)
+{
+	unsigned long val;
+	asm volatile("movl %%cr2,%0\n\t" :"=r" (val));
+	return val;
+}
+
+static fastcall void native_write_cr2(unsigned long val)
+{
+	asm volatile("movl %0,%%cr2": :"r" (val));
+}
+
+static fastcall unsigned long native_read_cr3(void)
+{
+	unsigned long val;
+	asm volatile("movl %%cr3,%0\n\t" :"=r" (val));
+	return val;
+}
+
+static fastcall void native_write_cr3(unsigned long val)
+{
+	asm volatile("movl %0,%%cr3": :"r" (val));
+}
+
+static fastcall unsigned long native_read_cr4(void)
+{
+	unsigned long val;
+	asm volatile("movl %%cr4,%0\n\t" :"=r" (val));
+	return val;
+}
+
+static fastcall unsigned long native_read_cr4_safe(void)
+{
+	unsigned long val;
+	/* This could fault if %cr4 does not exist */
+	asm("1: movl %%cr4, %0		\n"
+		"2:				\n"
+		".section __ex_table,\"a\"	\n"
+		".long 1b,2b			\n"
+		".previous			\n"
+		: "=r" (val): "0" (0));
+	return val;
+}
+
+static fastcall void native_write_cr4(unsigned long val)
+{
+	asm volatile("movl %0,%%cr4": :"r" (val));
+}
+
+static fastcall unsigned long native_save_fl(void)
+{
+	unsigned long f;
+	asm volatile("pushfl ; popl %0":"=g" (f): /* no input */);
+	return f;
+}
+
+static fastcall void native_restore_fl(unsigned long f)
+{
+	asm volatile("pushl %0 ; popfl": /* no output */
+			     :"g" (f)
+			     :"memory", "cc");
+}
+
+static fastcall void native_irq_disable(void)
+{
+	asm volatile("cli": : :"memory");
+}
+
+static fastcall void native_irq_enable(void)
+{
+	asm volatile("sti": : :"memory");
+}
+
+static fastcall void native_safe_halt(void)
+{
+	asm volatile("sti; hlt": : :"memory");
+}
+
+static fastcall void native_halt(void)
+{
+	asm volatile("hlt": : :"memory");
+}
+
+static fastcall void native_wbinvd(void)
+{
+	asm volatile("wbinvd": : :"memory");
+}
+
+static fastcall unsigned long long native_read_msr(unsigned int msr, int *err)
+{
+	unsigned long long val;
+
+	asm volatile("2: rdmsr ; xorl %0,%0\n"
+		     "1:\n\t"
+		     ".section .fixup,\"ax\"\n\t"
+		     "3:  movl %3,%0 ; jmp 1b\n\t"
+		     ".previous\n\t"
+ 		     ".section __ex_table,\"a\"\n"
+		     "   .align 4\n\t"
+		     "   .long 	2b,3b\n\t"
+		     ".previous"
+		     : "=r" (*err), "=A" (val)
+		     : "c" (msr), "i" (-EFAULT));
+
+	return val;
+}
+
+static fastcall int native_write_msr(unsigned int msr, unsigned long long val)
+{
+	int err;
+	asm volatile("2: wrmsr ; xorl %0,%0\n"
+		     "1:\n\t"
+		     ".section .fixup,\"ax\"\n\t"
+		     "3:  movl %4,%0 ; jmp 1b\n\t"
+		     ".previous\n\t"
+ 		     ".section __ex_table,\"a\"\n"
+		     "   .align 4\n\t"
+		     "   .long 	2b,3b\n\t"
+		     ".previous"
+		     : "=a" (err)
+		     : "c" (msr), "0" ((u32)val), "d" ((u32)(val>>32)),
+		       "i" (-EFAULT));
+	return err;
+}
+
+static fastcall unsigned long long native_read_tsc(void)
+{
+	unsigned long long val;
+	asm volatile("rdtsc" : "=A" (val));
+	return val;
+}
+
+static fastcall unsigned long long native_read_pmc(void)
+{
+	unsigned long long val;
+	asm volatile("rdpmc" : "=A" (val));
+	return val;
+}
+
+static fastcall void native_load_tr_desc(void)
+{
+	asm volatile("ltr %w0"::"q" (GDT_ENTRY_TSS*8));
+}
+
+static fastcall void native_load_gdt(const struct Xgt_desc_struct *dtr)
+{
+	asm volatile("lgdt %0"::"m" (*dtr));
+}
+
+static fastcall void native_load_idt(const struct Xgt_desc_struct *dtr)
+{
+	asm volatile("lidt %0"::"m" (*dtr));
+}
+
+static fastcall void native_store_gdt(struct Xgt_desc_struct *dtr)
+{
+	asm ("sgdt %0":"=m" (*dtr));
+}
+
+static fastcall void native_store_idt(struct Xgt_desc_struct *dtr)
+{
+	asm ("sidt %0":"=m" (*dtr));
+}
+
+static fastcall unsigned long native_store_tr(void)
+{
+	unsigned long tr;
+	asm ("str %0":"=r" (tr));
+	return tr;
+}
+
+static fastcall void native_load_tls(struct thread_struct *t, unsigned int cpu)
+{
+#define C(i) get_cpu_gdt_table(cpu)[GDT_ENTRY_TLS_MIN + i] = t->tls_array[i]
+	C(0); C(1); C(2);
+#undef C
+}
+
+static inline void native_write_dt_entry(void *dt, int entry, u32 entry_low, u32 entry_high)
+{
+	u32 *lp = (u32 *)((char *)dt + entry*8);
+	lp[0] = entry_low;
+	lp[1] = entry_high;
+}
+
+static fastcall void native_write_ldt_entry(void *dt, int entrynum, u32 low, u32 high)
+{
+	native_write_dt_entry(dt, entrynum, low, high);
+}
+
+static fastcall void native_write_gdt_entry(void *dt, int entrynum, u32 low, u32 high)
+{
+	native_write_dt_entry(dt, entrynum, low, high);
+}
+
+static fastcall void native_write_idt_entry(void *dt, int entrynum, u32 low, u32 high)
+{
+	native_write_dt_entry(dt, entrynum, low, high);
+}
+
+static fastcall void native_load_esp0(struct tss_struct *tss,
+				      struct thread_struct *thread)
+{
+	tss->esp0 = thread->esp0;
+
+	/* This can only happen when SEP is enabled, no need to test "SEP"arately */
+	if (unlikely(tss->ss1 != thread->sysenter_cs)) {
+		tss->ss1 = thread->sysenter_cs;
+		wrmsr(MSR_IA32_SYSENTER_CS, thread->sysenter_cs, 0);
+	}
+}
+
+static fastcall void native_io_delay(void)
+{
+	asm volatile("outb %al,$0x80");
+}
+
+/* These are in entry.S */
+extern fastcall void native_iret(void);
+extern fastcall void native_irq_enable_sysexit(void);
+
+static int __init print_banner(void)
+{
+	paravirt_ops.banner();
+	return 0;
+}
+core_initcall(print_banner);
+
+struct paravirt_ops paravirt_ops = {
+	.name = "bare hardware",
+	.paravirt_enabled = 0,
+	.kernel_rpl = 0,
+
+	.banner = default_banner,
+	.arch_setup = native_nop,
+	.memory_setup = machine_specific_memory_setup,
+	.get_wallclock = native_get_wallclock,
+	.set_wallclock = native_set_wallclock,
+	.time_init = time_init_hook,
+	.init_IRQ = native_init_IRQ,
+
+	.cpuid = native_cpuid,
+	.get_debugreg = native_get_debugreg,
+	.set_debugreg = native_set_debugreg,
+	.clts = native_clts,
+	.read_cr0 = native_read_cr0,
+	.write_cr0 = native_write_cr0,
+	.read_cr2 = native_read_cr2,
+	.write_cr2 = native_write_cr2,
+	.read_cr3 = native_read_cr3,
+	.write_cr3 = native_write_cr3,
+	.read_cr4 = native_read_cr4,
+	.read_cr4_safe = native_read_cr4_safe,
+	.write_cr4 = native_write_cr4,
+	.save_fl = native_save_fl,
+	.restore_fl = native_restore_fl,
+	.irq_disable = native_irq_disable,
+	.irq_enable = native_irq_enable,
+	.safe_halt = native_safe_halt,
+	.halt = native_halt,
+	.wbinvd = native_wbinvd,
+	.read_msr = native_read_msr,
+	.write_msr = native_write_msr,
+	.read_tsc = native_read_tsc,
+	.read_pmc = native_read_pmc,
+	.load_tr_desc = native_load_tr_desc,
+	.set_ldt = native_set_ldt,
+	.load_gdt = native_load_gdt,
+	.load_idt = native_load_idt,
+	.store_gdt = native_store_gdt,
+	.store_idt = native_store_idt,
+	.store_tr = native_store_tr,
+	.load_tls = native_load_tls,
+	.write_ldt_entry = native_write_ldt_entry,
+	.write_gdt_entry = native_write_gdt_entry,
+	.write_idt_entry = native_write_idt_entry,
+	.load_esp0 = native_load_esp0,
+
+	.set_iopl_mask = native_set_iopl_mask,
+	.io_delay = native_io_delay,
+	.const_udelay = __const_udelay,
+
+	.irq_enable_sysexit = native_irq_enable_sysexit,
+	.iret = native_iret,
+};
+EXPORT_SYMBOL(paravirt_ops);