x86/lguest: Remove lguest support

Lguest seems to be rather unused these days. It has seen only patches
ensuring it still builds the last two years and its official state is
"Odd Fixes".

Remove it in order to be able to clean up the paravirt code.

Signed-off-by: Juergen Gross <jgross@suse.com>
Acked-by: Rusty Russell <rusty@rustcorp.com.au>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: boris.ostrovsky@oracle.com
Cc: lguest@lists.ozlabs.org
Cc: rusty@rustcorp.com.au
Cc: xen-devel@lists.xenproject.org
Link: http://lkml.kernel.org/r/20170816173157.8633-3-jgross@suse.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

1 files changed, 0 insertions, 228 deletions

diff --git a/drivers/lguest/segments.c b/drivers/lguest/segments.c
deleted file mode 100644
index c4fb424dfddb..000000000000
--- a/drivers/lguest/segments.c
+++ /dev/null
@@ -1,228 +0,0 @@
-/*P:600
- * The x86 architecture has segments, which involve a table of descriptors
- * which can be used to do funky things with virtual address interpretation.
- * We originally used to use segments so the Guest couldn't alter the
- * Guest<->Host Switcher, and then we had to trim Guest segments, and restore
- * for userspace per-thread segments, but trim again for on userspace->kernel
- * transitions...  This nightmarish creation was contained within this file,
- * where we knew not to tread without heavy armament and a change of underwear.
- *
- * In these modern times, the segment handling code consists of simple sanity
- * checks, and the worst you'll experience reading this code is butterfly-rash
- * from frolicking through its parklike serenity.
-:*/
-#include "lg.h"
-
-/*H:600
- * Segments & The Global Descriptor Table
- *
- * (That title sounds like a bad Nerdcore group.  Not to suggest that there are
- * any good Nerdcore groups, but in high school a friend of mine had a band
- * called Joe Fish and the Chips, so there are definitely worse band names).
- *
- * To refresh: the GDT is a table of 8-byte values describing segments.  Once
- * set up, these segments can be loaded into one of the 6 "segment registers".
- *
- * GDT entries are passed around as "struct desc_struct"s, which like IDT
- * entries are split into two 32-bit members, "a" and "b".  One day, someone
- * will clean that up, and be declared a Hero.  (No pressure, I'm just saying).
- *
- * Anyway, the GDT entry contains a base (the start address of the segment), a
- * limit (the size of the segment - 1), and some flags.  Sounds simple, and it
- * would be, except those zany Intel engineers decided that it was too boring
- * to put the base at one end, the limit at the other, and the flags in
- * between.  They decided to shotgun the bits at random throughout the 8 bytes,
- * like so:
- *
- * 0               16                     40       48  52  56     63
- * [ limit part 1 ][     base part 1     ][ flags ][li][fl][base ]
- *                                                  mit ags part 2
- *                                                part 2
- *
- * As a result, this file contains a certain amount of magic numeracy.  Let's
- * begin.
- */
-
-/*
- * There are several entries we don't let the Guest set.  The TSS entry is the
- * "Task State Segment" which controls all kinds of delicate things.  The
- * LGUEST_CS and LGUEST_DS entries are reserved for the Switcher, and the
- * the Guest can't be trusted to deal with double faults.
- */
-static bool ignored_gdt(unsigned int num)
-{
-	return (num == GDT_ENTRY_TSS
-		|| num == GDT_ENTRY_LGUEST_CS
-		|| num == GDT_ENTRY_LGUEST_DS
-		|| num == GDT_ENTRY_DOUBLEFAULT_TSS);
-}
-
-/*H:630
- * Once the Guest gave us new GDT entries, we fix them up a little.  We
- * don't care if they're invalid: the worst that can happen is a General
- * Protection Fault in the Switcher when it restores a Guest segment register
- * which tries to use that entry.  Then we kill the Guest for causing such a
- * mess: the message will be "unhandled trap 256".
- */
-static void fixup_gdt_table(struct lg_cpu *cpu, unsigned start, unsigned end)
-{
-	unsigned int i;
-
-	for (i = start; i < end; i++) {
-		/*
-		 * We never copy these ones to real GDT, so we don't care what
-		 * they say
-		 */
-		if (ignored_gdt(i))
-			continue;
-
-		/*
-		 * Segment descriptors contain a privilege level: the Guest is
-		 * sometimes careless and leaves this as 0, even though it's
-		 * running at privilege level 1.  If so, we fix it here.
-		 */
-		if (cpu->arch.gdt[i].dpl == 0)
-			cpu->arch.gdt[i].dpl |= GUEST_PL;
-
-		/*
-		 * Each descriptor has an "accessed" bit.  If we don't set it
-		 * now, the CPU will try to set it when the Guest first loads
-		 * that entry into a segment register.  But the GDT isn't
-		 * writable by the Guest, so bad things can happen.
-		 */
-		cpu->arch.gdt[i].type |= 0x1;
-	}
-}
-
-/*H:610
- * Like the IDT, we never simply use the GDT the Guest gives us.  We keep
- * a GDT for each CPU, and copy across the Guest's entries each time we want to
- * run the Guest on that CPU.
- *
- * This routine is called at boot or modprobe time for each CPU to set up the
- * constant GDT entries: the ones which are the same no matter what Guest we're
- * running.
- */
-void setup_default_gdt_entries(struct lguest_ro_state *state)
-{
-	struct desc_struct *gdt = state->guest_gdt;
-	unsigned long tss = (unsigned long)&state->guest_tss;
-
-	/* The Switcher segments are full 0-4G segments, privilege level 0 */
-	gdt[GDT_ENTRY_LGUEST_CS] = FULL_EXEC_SEGMENT;
-	gdt[GDT_ENTRY_LGUEST_DS] = FULL_SEGMENT;
-
-	/*
-	 * The TSS segment refers to the TSS entry for this particular CPU.
-	 */
-	gdt[GDT_ENTRY_TSS].a = 0;
-	gdt[GDT_ENTRY_TSS].b = 0;
-
-	gdt[GDT_ENTRY_TSS].limit0 = 0x67;
-	gdt[GDT_ENTRY_TSS].base0  = tss & 0xFFFF;
-	gdt[GDT_ENTRY_TSS].base1  = (tss >> 16) & 0xFF;
-	gdt[GDT_ENTRY_TSS].base2  = tss >> 24;
-	gdt[GDT_ENTRY_TSS].type   = 0x9; /* 32-bit TSS (available) */
-	gdt[GDT_ENTRY_TSS].p      = 0x1; /* Entry is present */
-	gdt[GDT_ENTRY_TSS].dpl    = 0x0; /* Privilege level 0 */
-	gdt[GDT_ENTRY_TSS].s      = 0x0; /* system segment */
-
-}
-
-/*
- * This routine sets up the initial Guest GDT for booting.  All entries start
- * as 0 (unusable).
- */
-void setup_guest_gdt(struct lg_cpu *cpu)
-{
-	/*
-	 * Start with full 0-4G segments...except the Guest is allowed to use
-	 * them, so set the privilege level appropriately in the flags.
-	 */
-	cpu->arch.gdt[GDT_ENTRY_KERNEL_CS] = FULL_EXEC_SEGMENT;
-	cpu->arch.gdt[GDT_ENTRY_KERNEL_DS] = FULL_SEGMENT;
-	cpu->arch.gdt[GDT_ENTRY_KERNEL_CS].dpl |= GUEST_PL;
-	cpu->arch.gdt[GDT_ENTRY_KERNEL_DS].dpl |= GUEST_PL;
-}
-
-/*H:650
- * An optimization of copy_gdt(), for just the three "thead-local storage"
- * entries.
- */
-void copy_gdt_tls(const struct lg_cpu *cpu, struct desc_struct *gdt)
-{
-	unsigned int i;
-
-	for (i = GDT_ENTRY_TLS_MIN; i <= GDT_ENTRY_TLS_MAX; i++)
-		gdt[i] = cpu->arch.gdt[i];
-}
-
-/*H:640
- * When the Guest is run on a different CPU, or the GDT entries have changed,
- * copy_gdt() is called to copy the Guest's GDT entries across to this CPU's
- * GDT.
- */
-void copy_gdt(const struct lg_cpu *cpu, struct desc_struct *gdt)
-{
-	unsigned int i;
-
-	/*
-	 * The default entries from setup_default_gdt_entries() are not
-	 * replaced.  See ignored_gdt() above.
-	 */
-	for (i = 0; i < GDT_ENTRIES; i++)
-		if (!ignored_gdt(i))
-			gdt[i] = cpu->arch.gdt[i];
-}
-
-/*H:620
- * This is where the Guest asks us to load a new GDT entry
- * (LHCALL_LOAD_GDT_ENTRY).  We tweak the entry and copy it in.
- */
-void load_guest_gdt_entry(struct lg_cpu *cpu, u32 num, u32 lo, u32 hi)
-{
-	/*
-	 * We assume the Guest has the same number of GDT entries as the
-	 * Host, otherwise we'd have to dynamically allocate the Guest GDT.
-	 */
-	if (num >= ARRAY_SIZE(cpu->arch.gdt)) {
-		kill_guest(cpu, "too many gdt entries %i", num);
-		return;
-	}
-
-	/* Set it up, then fix it. */
-	cpu->arch.gdt[num].a = lo;
-	cpu->arch.gdt[num].b = hi;
-	fixup_gdt_table(cpu, num, num+1);
-	/*
-	 * Mark that the GDT changed so the core knows it has to copy it again,
-	 * even if the Guest is run on the same CPU.
-	 */
-	cpu->changed |= CHANGED_GDT;
-}
-
-/*
- * This is the fast-track version for just changing the three TLS entries.
- * Remember that this happens on every context switch, so it's worth
- * optimizing.  But wouldn't it be neater to have a single hypercall to cover
- * both cases?
- */
-void guest_load_tls(struct lg_cpu *cpu, unsigned long gtls)
-{
-	struct desc_struct *tls = &cpu->arch.gdt[GDT_ENTRY_TLS_MIN];
-
-	__lgread(cpu, tls, gtls, sizeof(*tls)*GDT_ENTRY_TLS_ENTRIES);
-	fixup_gdt_table(cpu, GDT_ENTRY_TLS_MIN, GDT_ENTRY_TLS_MAX+1);
-	/* Note that just the TLS entries have changed. */
-	cpu->changed |= CHANGED_GDT_TLS;
-}
-
-/*H:660
- * With this, we have finished the Host.
- *
- * Five of the seven parts of our task are complete.  You have made it through
- * the Bit of Despair (I think that's somewhere in the page table code,
- * myself).
- *
- * Next, we examine "make Switcher".  It's short, but intense.
- */