Add initial code for disabling PV descriptors

* xen/configfrag.ac (--disable-pv-descriptors): Add option
* i386/xen/xen_boothdr.S (XEN_ELFNOTE_FEATURES) [!MACH_PV_DESCRIPTORS]: Add
writable_descriptor_tables.
* i386/i386/gdt.c: Turn appropriate MACH_XEN/MACH_HYP tests into
MACH_PV_DESCRIPTORS tests.
* i386/i386/gdt.h: Likewise.
* i386/i386/i386asm.sym: Likewise.
* i386/i386/idt.c: Likewise.
* i386/i386/idt_inittab.S: Likewise.
* i386/i386/ldt.c: Likewise.
* i386/i386/pcb.c: Likewise.
* i386/i386/seg.h: Likewise.
* i386/i386/user_ldt.c: Likewise.
* i386/i386/user_ldt.h: Likewise.

12 files changed, 73 insertions, 55 deletions

diff --git a/i386/i386/gdt.c b/i386/i386/gdt.c
index f26a50c..b686faa 100644
--- a/i386/i386/gdt.c
+++ b/i386/i386/gdt.c
@@ -39,10 +39,10 @@
 #include "seg.h"
 #include "gdt.h"
 
-#ifdef	MACH_XEN
+#ifdef	MACH_PV_DESCRIPTORS
 /* It is actually defined in xen_boothdr.S */
 extern
-#endif	/* MACH_XEN */
+#endif	/* MACH_PV_DESCRIPTORS */
 struct real_descriptor gdt[GDTSZ];
 
 void
@@ -57,14 +57,14 @@ gdt_init()
 			    LINEAR_MIN_KERNEL_ADDRESS - VM_MIN_KERNEL_ADDRESS,
 			    LINEAR_MAX_KERNEL_ADDRESS - (LINEAR_MIN_KERNEL_ADDRESS - VM_MIN_KERNEL_ADDRESS) - 1,
 			    ACC_PL_K|ACC_DATA_W, SZ_32);
-#ifndef	MACH_HYP
+#ifndef	MACH_PV_DESCRIPTORS
 	fill_gdt_descriptor(LINEAR_DS,
 			    0,
 			    0xffffffff,
 			    ACC_PL_K|ACC_DATA_W, SZ_32);
-#endif	/* MACH_HYP */
+#endif	/* MACH_PV_DESCRIPTORS */
 
-#ifdef	MACH_XEN
+#ifdef	MACH_PV_DESCRIPTORS
 	unsigned long frame = kv_to_mfn(gdt);
 	pmap_set_page_readonly(gdt);
 	if (hyp_set_gdt(kv_to_la(&frame), GDTSZ))
@@ -75,7 +75,7 @@ gdt_init()
 	if (hyp_vm_assist(VMASST_CMD_enable, VMASST_TYPE_4gb_segments_notify))
 		panic("couldn't set 4gb segments vm assist notify");
 #endif
-#else	/* MACH_XEN */
+#else	/* MACH_PV_DESCRIPTORS */
 	/* Load the new GDT.  */
 	{
 		struct pseudo_descriptor pdesc;
@@ -84,7 +84,7 @@ gdt_init()
 		pdesc.linear_base = kvtolin(&gdt);
 		lgdt(&pdesc);
 	}
-#endif	/* MACH_XEN */
+#endif	/* MACH_PV_DESCRIPTORS */
 
 	/* Reload all the segment registers from the new GDT.
 	   We must load ds and es with 0 before loading them with KERNEL_DS
diff --git a/i386/i386/gdt.h b/i386/i386/gdt.h
index 41ace79..788f48a 100644
--- a/i386/i386/gdt.h
+++ b/i386/i386/gdt.h
@@ -40,14 +40,14 @@
  */
 #define	KERNEL_CS	(0x08 | KERNEL_RING)		/* kernel code */
 #define	KERNEL_DS	(0x10 | KERNEL_RING)		/* kernel data */
-#ifndef	MACH_XEN
+#ifndef	MACH_PV_DESCRIPTORS
 #define	KERNEL_LDT	0x18		/* master LDT */
-#endif	/* MACH_XEN */
+#endif	/* MACH_PV_DESCRIPTORS */
 #define	KERNEL_TSS	0x20		/* master TSS (uniprocessor) */
 #define	USER_LDT	0x28		/* place for per-thread LDT */
 #define	USER_TSS	0x30		/* place for per-thread TSS
 					   that holds IO bitmap */
-#ifndef	MACH_HYP
+#ifndef	MACH_PV_DESCRIPTORS
 #define	LINEAR_DS	0x38		/* linear mapping */
 #endif	/* MACH_HYP */
 /*			0x40		   was USER_FPREGS, now free */
diff --git a/i386/i386/i386asm.sym b/i386/i386/i386asm.sym
index c4e4648..bcee28f 100644
--- a/i386/i386/i386asm.sym
+++ b/i386/i386/i386asm.sym
@@ -124,9 +124,9 @@ expr	KERNEL_RING
 expr	KERNEL_CS
 expr	KERNEL_DS
 expr	KERNEL_TSS
-#ifndef	MACH_XEN
+#ifndef	MACH_PV_DESCRIPTORS
 expr	KERNEL_LDT
-#endif	/* MACH_XEN */
+#endif	/* MACH_PV_DESCRIPTORS */
 
 expr	(VM_MIN_KERNEL_ADDRESS>>PDESHIFT)*sizeof(pt_entry_t)	KERNELBASEPDE
 
diff --git a/i386/i386/idt.c b/i386/i386/idt.c
index b5e3d08..882764f 100644
--- a/i386/i386/idt.c
+++ b/i386/i386/idt.c
@@ -38,10 +38,10 @@ extern struct idt_init_entry idt_inittab[];
 
 void idt_init()
 {
-#ifdef	MACH_HYP
+#ifdef	MACH_PV_DESCRIPTORS
 	if (hyp_set_trap_table(kvtolin(idt_inittab)))
 		panic("couldn't set trap table\n");
-#else	/* MACH_HYP */
+#else	/* MACH_PV_DESCRIPTORS */
 	struct idt_init_entry *iie = idt_inittab;
 
 	/* Initialize the exception vectors from the idt_inittab.  */
@@ -59,6 +59,6 @@ void idt_init()
 		pdesc.linear_base = kvtolin(&idt);
 		lidt(&pdesc);
 	}
-#endif	/* MACH_HYP */
+#endif	/* MACH_PV_DESCRIPTORS */
 }
 
diff --git a/i386/i386/idt_inittab.S b/i386/i386/idt_inittab.S
index 63e554b..36093b6 100644
--- a/i386/i386/idt_inittab.S
+++ b/i386/i386/idt_inittab.S
@@ -39,7 +39,7 @@ ENTRY(idt_inittab)
 /*
  * Interrupt descriptor table and code vectors for it.
  */
-#ifdef	MACH_XEN
+#ifdef	MACH_PV_DESCRIPTORS
 #define	IDT_ENTRY(n,entry,type) \
 	.data	2		;\
 	.byte	n		;\
@@ -47,14 +47,14 @@ ENTRY(idt_inittab)
 	.word	KERNEL_CS	;\
 	.long	entry		;\
 	.text
-#else	/* MACH_XEN */
+#else	/* MACH_PV_DESCRIPTORS */
 #define	IDT_ENTRY(n,entry,type) \
 	.data	2		;\
 	.long	entry		;\
 	.word	n		;\
 	.word	type		;\
 	.text
-#endif	/* MACH_XEN */
+#endif	/* MACH_PV_DESCRIPTORS */
 
 /*
  * No error code.  Clear error code and push trap number.
@@ -108,7 +108,7 @@ EXCEP_SPC(0x0b,t_segnp)
 EXCEP_ERR(0x0c,t_stack_fault)
 EXCEP_SPC(0x0d,t_gen_prot)
 EXCEP_SPC(0x0e,t_page_fault)
-#ifdef MACH_XEN
+#ifdef	MACH_PV_DESCRIPTORS
 EXCEP_ERR(0x0f,t_trap_0f)
 #else
 EXCEPTION(0x0f,t_trap_0f)
diff --git a/i386/i386/ldt.c b/i386/i386/ldt.c
index 0ef7a8c..58af94b 100644
--- a/i386/i386/ldt.c
+++ b/i386/i386/ldt.c
@@ -39,23 +39,23 @@
 
 extern int syscall();
 
-#ifdef	MACH_XEN
+#ifdef	MACH_PV_DESCRIPTORS
 /* It is actually defined in xen_boothdr.S */
 extern
-#endif	/* MACH_XEN */
+#endif	/* MACH_PV_DESCRIPTORS */
 struct real_descriptor ldt[LDTSZ];
 
 void
 ldt_init()
 {
-#ifdef	MACH_XEN
+#ifdef	MACH_PV_DESCRIPTORS
 	pmap_set_page_readwrite(ldt);
-#else	/* MACH_XEN */
+#else	/* MACH_PV_DESCRIPTORS */
 	/* Initialize the master LDT descriptor in the GDT.  */
 	fill_gdt_descriptor(KERNEL_LDT,
 			    kvtolin(&ldt), sizeof(ldt)-1,
 			    ACC_PL_K|ACC_LDT, 0);
-#endif	/* MACH_XEN */
+#endif	/* MACH_PV_DESCRIPTORS */
 
 	/* Initialize the LDT descriptors.  */
 	fill_ldt_gate(USER_SCALL,
@@ -72,9 +72,9 @@ ldt_init()
 			    ACC_PL_U|ACC_DATA_W, SZ_32);
 
 	/* Activate the LDT.  */
-#ifdef	MACH_HYP
+#ifdef	MACH_PV_DESCRIPTORS
 	hyp_set_ldt(&ldt, LDTSZ);
-#else	/* MACH_HYP */
+#else	/* MACH_PV_DESCRIPTORS */
 	lldt(KERNEL_LDT);
-#endif	/* MACH_HYP */
+#endif	/* MACH_PV_DESCRIPTORS */
 }
diff --git a/i386/i386/pcb.c b/i386/i386/pcb.c
index 362d990..8d37d69 100644
--- a/i386/i386/pcb.c
+++ b/i386/i386/pcb.c
@@ -173,28 +173,28 @@ void switch_ktss(pcb)
 	    /*
 	     * Use system LDT.
 	     */
-#ifdef	MACH_HYP
+#ifdef	MACH_PV_DESCRIPTORS
 	    hyp_set_ldt(&ldt, LDTSZ);
-#else	/* MACH_HYP */
+#else	/* MACH_PV_DESCRIPTORS */
 	    set_ldt(KERNEL_LDT);
-#endif	/* MACH_HYP */
+#endif	/* MACH_PV_DESCRIPTORS */
 	}
 	else {
 	    /*
 	     * Thread has its own LDT.
 	     */
-#ifdef	MACH_HYP
+#ifdef	MACH_PV_DESCRIPTORS
 	    hyp_set_ldt(tldt->ldt,
 	    		(tldt->desc.limit_low|(tldt->desc.limit_high<<16)) /
 				sizeof(struct real_descriptor));
-#else	/* MACH_HYP */
+#else	/* MACH_PV_DESCRIPTORS */
 	    *gdt_desc_p(mycpu,USER_LDT) = tldt->desc;
 	    set_ldt(USER_LDT);
-#endif	/* MACH_HYP */
+#endif	/* MACH_PV_DESCRIPTORS */
 	}
     }
 
-#ifdef	MACH_XEN
+#ifdef	MACH_PV_DESCRIPTORS
     {
 	int i;
 	for (i=0; i < USER_GDT_SLOTS; i++) {
@@ -206,14 +206,14 @@ void switch_ktss(pcb)
 	    }
 	}
     }
-#else /* MACH_XEN */
+#else /* MACH_PV_DESCRIPTORS */
 
     /* Copy in the per-thread GDT slots.  No reloading is necessary
        because just restoring the segment registers on the way back to
        user mode reloads the shadow registers from the in-memory GDT.  */
     memcpy (gdt_desc_p (mycpu, USER_GDT),
         pcb->ims.user_gdt, sizeof pcb->ims.user_gdt);
-#endif /* MACH_XEN */
+#endif /* MACH_PV_DESCRIPTORS */
 
 	/*
 	 * Load the floating-point context, if necessary.
diff --git a/i386/i386/seg.h b/i386/i386/seg.h
index a7f6573..fe7acc1 100644
--- a/i386/i386/seg.h
+++ b/i386/i386/seg.h
@@ -161,12 +161,12 @@ MACH_INLINE void
 fill_descriptor(struct real_descriptor *_desc, unsigned base, unsigned limit,
 		unsigned char access, unsigned char sizebits)
 {
-	/* TODO: when !MACH_XEN, setting desc and just memcpy isn't simpler actually */
-#ifdef	MACH_XEN
+	/* TODO: when !MACH_PV_DESCRIPTORS, setting desc and just memcpy isn't simpler actually */
+#ifdef	MACH_PV_DESCRIPTORS
 	struct real_descriptor __desc, *desc = &__desc;
-#else	/* MACH_XEN */
+#else	/* MACH_PV_DESCRIPTORS */
 	struct real_descriptor *desc = _desc;
-#endif	/* MACH_XEN */
+#endif	/* MACH_PV_DESCRIPTORS */
 	if (limit > 0xfffff)
 	{
 		limit >>= 12;
@@ -179,10 +179,10 @@ fill_descriptor(struct real_descriptor *_desc, unsigned base, unsigned limit,
 	desc->limit_high = limit >> 16;
 	desc->granularity = sizebits;
 	desc->base_high = base >> 24;
-#ifdef	MACH_XEN
+#ifdef	MACH_PV_DESCRIPTORS
 	if (hyp_do_update_descriptor(kv_to_ma(_desc), *(uint64_t*)desc))
 		panic("couldn't update descriptor(%p to %08lx%08lx)\n", (vm_offset_t) kv_to_ma(_desc), *(((unsigned long*)desc)+1), *(unsigned long *)desc);
-#endif	/* MACH_XEN */
+#endif	/* MACH_PV_DESCRIPTORS */
 }
 
 /* Fill a gate with particular values.  */
diff --git a/i386/i386/user_ldt.c b/i386/i386/user_ldt.c
index dfe6b1e..70ef7cb 100644
--- a/i386/i386/user_ldt.c
+++ b/i386/i386/user_ldt.c
@@ -196,17 +196,17 @@ i386_set_ldt(thread, first_selector, desc_list, count, desc_list_inline)
 	    if (new_ldt == 0) {
 		simple_unlock(&pcb->lock);
 
-#ifdef	MACH_XEN
+#ifdef	MACH_PV_DESCRIPTORS
 		/* LDT needs to be aligned on a page */
 		vm_offset_t alloc = kalloc(ldt_size_needed + PAGE_SIZE + offsetof(struct user_ldt, ldt));
 		new_ldt = (user_ldt_t) (round_page((alloc + offsetof(struct user_ldt, ldt))) - offsetof(struct user_ldt, ldt));
 		new_ldt->alloc = alloc;
 		
-#else	/* MACH_XEN */
+#else	/* MACH_PV_DESCRIPTORS */
 		new_ldt = (user_ldt_t)
 				kalloc(ldt_size_needed
 				       + sizeof(struct real_descriptor));
-#endif	/* MACH_XEN */
+#endif	/* MACH_PV_DESCRIPTORS */
 		/*
 		 *	Build a descriptor that describes the
 		 *	LDT itself
@@ -272,7 +272,7 @@ i386_set_ldt(thread, first_selector, desc_list, count, desc_list_inline)
 	simple_unlock(&pcb->lock);
 
 	if (new_ldt)
-#ifdef	MACH_XEN
+#ifdef	MACH_PV_DESCRIPTORS
 	{
 	    int i;
 	    for (i=0; i<(new_ldt->desc.limit_low + 1)/sizeof(struct real_descriptor); i+=PAGE_SIZE/sizeof(struct real_descriptor))
@@ -280,11 +280,11 @@ i386_set_ldt(thread, first_selector, desc_list, count, desc_list_inline)
 	    kfree(new_ldt->alloc, new_ldt->desc.limit_low + 1
 		+ PAGE_SIZE + offsetof(struct user_ldt, ldt));
 	}
-#else	/* MACH_XEN */
+#else	/* MACH_PV_DESCRIPTORS */
 	    kfree((vm_offset_t)new_ldt,
 		  new_ldt->desc.limit_low + 1
 		+ sizeof(struct real_descriptor));
-#endif	/* MACH_XEN */
+#endif	/* MACH_PV_DESCRIPTORS */
 
 	/*
 	 * Free the descriptor list, if it was
@@ -417,17 +417,17 @@ void
 user_ldt_free(user_ldt)
 	user_ldt_t	user_ldt;
 {
-#ifdef	MACH_XEN
+#ifdef	MACH_PV_DESCRIPTORS
 	int i;
 	for (i=0; i<(user_ldt->desc.limit_low + 1)/sizeof(struct real_descriptor); i+=PAGE_SIZE/sizeof(struct real_descriptor))
 		pmap_set_page_readwrite(&user_ldt->ldt[i]);
 	kfree(user_ldt->alloc, user_ldt->desc.limit_low + 1
 		+ PAGE_SIZE + offsetof(struct user_ldt, ldt));
-#else	/* MACH_XEN */
+#else	/* MACH_PV_DESCRIPTORS */
 	kfree((vm_offset_t)user_ldt,
 		user_ldt->desc.limit_low + 1
 		+ sizeof(struct real_descriptor));
-#endif	/* MACH_XEN */
+#endif	/* MACH_PV_DESCRIPTORS */
 }
 
 
diff --git a/i386/i386/user_ldt.h b/i386/i386/user_ldt.h
index 8d16ed8..6c6c858 100644
--- a/i386/i386/user_ldt.h
+++ b/i386/i386/user_ldt.h
@@ -36,9 +36,9 @@
 #include <i386/seg.h>
 
 struct user_ldt {
-#ifdef	MACH_XEN
+#ifdef	MACH_PV_DESCRIPTORS
 	vm_offset_t		alloc;	/* allocation before alignment */
-#endif	/* MACH_XEN */
+#endif	/* MACH_PV_DESCRIPTORS */
 	struct real_descriptor	desc;	/* descriptor for self */
 	struct real_descriptor	ldt[1];	/* descriptor table (variable) */
 };
diff --git a/i386/xen/xen_boothdr.S b/i386/xen/xen_boothdr.S
index eacf0d8..4e2fb51 100644
--- a/i386/xen/xen_boothdr.S
+++ b/i386/xen/xen_boothdr.S
@@ -36,6 +36,9 @@
 #else	/* MACH_PSEUDO_PHYS */
 	.ascii	",FEATURES=!auto_translated_physmap"
 #endif
+#ifndef	MACH_PV_DESCRIPTORS
+	.ascii	"|writable_descriptor_tables"
+#endif	/* MACH_PV_DESCRIPTORS */
 	.byte	0
 
 /* Macro taken from linux/include/linux/elfnote.h */
@@ -68,8 +71,11 @@
 #ifdef MACH_PSEUDO_PHYS
 						"pae_pgdir_above_4gb"
 #else /* MACH_PSEUDO_PHYS */
-						"!auto_translated_physmap|"
+						"!auto_translated_physmap"
 #endif
+#ifndef	MACH_PV_DESCRIPTORS
+						"|writable_descriptor_tables"
+#endif	/* MACH_PV_DESCRIPTORS */
 	)
 
 #include <mach/machine/asm.h>
diff --git a/xen/configfrag.ac b/xen/configfrag.ac
index eb68996..d0705a4 100644
--- a/xen/configfrag.ac
+++ b/xen/configfrag.ac
@@ -25,8 +25,10 @@ dnl 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
   AC_DEFINE([MACH_HYP], [], [be a hypervisor guest])
   AM_CONDITIONAL([PLATFORM_xen], [true])
 
+dnl These are experimental
+
   AC_ARG_ENABLE([pseudo-phys],
-    AS_HELP_STRING([--enable-pseudo-phys], [Pseudo physical support]))
+    AS_HELP_STRING([--disable-pseudo-phys], [Pseudo physical pages support]))
   [if [ x"$enable_pseudo_phys" = xno ]; then]
     AM_CONDITIONAL([enable_pseudo_phys], [false])
   [else]
@@ -34,9 +36,19 @@ dnl 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
     AM_CONDITIONAL([enable_pseudo_phys], [true])
   [fi]
 
+  AC_ARG_ENABLE([pv-descriptors],
+    AS_HELP_STRING([--disable-pv-descriptors], [Paravirtualized segment descriptors support]))
+  [if [ x"$enable_pv_descriptors" = xno ]; then]
+    AM_CONDITIONAL([enable_pv_descriptors], [false])
+  [else]
+    AC_DEFINE([MACH_PV_DESCRIPTORS], [], [Enable paravirtualized segment descriptors support])
+    AM_CONDITIONAL([enable_pv_descriptors], [true])
+  [fi]
+
 [else]
   AM_CONDITIONAL([PLATFORM_xen], [false])
   AM_CONDITIONAL([enable_pseudo_phys], [false])
+  AM_CONDITIONAL([enable_pv_descriptors], [false])
 [fi]
 
 dnl Local Variables: