mirror of https://gitee.com/openkylin/linux.git
738 lines
24 KiB
C
738 lines
24 KiB
C
/*
|
|
* Copyright (C) 2006, Rusty Russell <rusty@rustcorp.com.au> IBM Corporation.
|
|
* Copyright (C) 2007, Jes Sorensen <jes@sgi.com> SGI.
|
|
*
|
|
* 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, GOOD TITLE or
|
|
* NON INFRINGEMENT. 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., 675 Mass Ave, Cambridge, MA 02139, USA.
|
|
*/
|
|
/*P:450
|
|
* This file contains the x86-specific lguest code. It used to be all
|
|
* mixed in with drivers/lguest/core.c but several foolhardy code slashers
|
|
* wrestled most of the dependencies out to here in preparation for porting
|
|
* lguest to other architectures (see what I mean by foolhardy?).
|
|
*
|
|
* This also contains a couple of non-obvious setup and teardown pieces which
|
|
* were implemented after days of debugging pain.
|
|
:*/
|
|
#include <linux/kernel.h>
|
|
#include <linux/start_kernel.h>
|
|
#include <linux/string.h>
|
|
#include <linux/console.h>
|
|
#include <linux/screen_info.h>
|
|
#include <linux/irq.h>
|
|
#include <linux/interrupt.h>
|
|
#include <linux/clocksource.h>
|
|
#include <linux/clockchips.h>
|
|
#include <linux/cpu.h>
|
|
#include <linux/lguest.h>
|
|
#include <linux/lguest_launcher.h>
|
|
#include <asm/paravirt.h>
|
|
#include <asm/param.h>
|
|
#include <asm/page.h>
|
|
#include <asm/pgtable.h>
|
|
#include <asm/desc.h>
|
|
#include <asm/setup.h>
|
|
#include <asm/lguest.h>
|
|
#include <asm/uaccess.h>
|
|
#include <asm/fpu/internal.h>
|
|
#include <asm/tlbflush.h>
|
|
#include "../lg.h"
|
|
|
|
static int cpu_had_pge;
|
|
|
|
static struct {
|
|
unsigned long offset;
|
|
unsigned short segment;
|
|
} lguest_entry;
|
|
|
|
/* Offset from where switcher.S was compiled to where we've copied it */
|
|
static unsigned long switcher_offset(void)
|
|
{
|
|
return switcher_addr - (unsigned long)start_switcher_text;
|
|
}
|
|
|
|
/* This cpu's struct lguest_pages (after the Switcher text page) */
|
|
static struct lguest_pages *lguest_pages(unsigned int cpu)
|
|
{
|
|
return &(((struct lguest_pages *)(switcher_addr + PAGE_SIZE))[cpu]);
|
|
}
|
|
|
|
static DEFINE_PER_CPU(struct lg_cpu *, lg_last_cpu);
|
|
|
|
/*S:010
|
|
* We approach the Switcher.
|
|
*
|
|
* Remember that each CPU has two pages which are visible to the Guest when it
|
|
* runs on that CPU. This has to contain the state for that Guest: we copy the
|
|
* state in just before we run the Guest.
|
|
*
|
|
* Each Guest has "changed" flags which indicate what has changed in the Guest
|
|
* since it last ran. We saw this set in interrupts_and_traps.c and
|
|
* segments.c.
|
|
*/
|
|
static void copy_in_guest_info(struct lg_cpu *cpu, struct lguest_pages *pages)
|
|
{
|
|
/*
|
|
* Copying all this data can be quite expensive. We usually run the
|
|
* same Guest we ran last time (and that Guest hasn't run anywhere else
|
|
* meanwhile). If that's not the case, we pretend everything in the
|
|
* Guest has changed.
|
|
*/
|
|
if (__this_cpu_read(lg_last_cpu) != cpu || cpu->last_pages != pages) {
|
|
__this_cpu_write(lg_last_cpu, cpu);
|
|
cpu->last_pages = pages;
|
|
cpu->changed = CHANGED_ALL;
|
|
}
|
|
|
|
/*
|
|
* These copies are pretty cheap, so we do them unconditionally: */
|
|
/* Save the current Host top-level page directory.
|
|
*/
|
|
pages->state.host_cr3 = __pa(current->mm->pgd);
|
|
/*
|
|
* Set up the Guest's page tables to see this CPU's pages (and no
|
|
* other CPU's pages).
|
|
*/
|
|
map_switcher_in_guest(cpu, pages);
|
|
/*
|
|
* Set up the two "TSS" members which tell the CPU what stack to use
|
|
* for traps which do directly into the Guest (ie. traps at privilege
|
|
* level 1).
|
|
*/
|
|
pages->state.guest_tss.sp1 = cpu->esp1;
|
|
pages->state.guest_tss.ss1 = cpu->ss1;
|
|
|
|
/* Copy direct-to-Guest trap entries. */
|
|
if (cpu->changed & CHANGED_IDT)
|
|
copy_traps(cpu, pages->state.guest_idt, default_idt_entries);
|
|
|
|
/* Copy all GDT entries which the Guest can change. */
|
|
if (cpu->changed & CHANGED_GDT)
|
|
copy_gdt(cpu, pages->state.guest_gdt);
|
|
/* If only the TLS entries have changed, copy them. */
|
|
else if (cpu->changed & CHANGED_GDT_TLS)
|
|
copy_gdt_tls(cpu, pages->state.guest_gdt);
|
|
|
|
/* Mark the Guest as unchanged for next time. */
|
|
cpu->changed = 0;
|
|
}
|
|
|
|
/* Finally: the code to actually call into the Switcher to run the Guest. */
|
|
static void run_guest_once(struct lg_cpu *cpu, struct lguest_pages *pages)
|
|
{
|
|
/* This is a dummy value we need for GCC's sake. */
|
|
unsigned int clobber;
|
|
|
|
/*
|
|
* Copy the guest-specific information into this CPU's "struct
|
|
* lguest_pages".
|
|
*/
|
|
copy_in_guest_info(cpu, pages);
|
|
|
|
/*
|
|
* Set the trap number to 256 (impossible value). If we fault while
|
|
* switching to the Guest (bad segment registers or bug), this will
|
|
* cause us to abort the Guest.
|
|
*/
|
|
cpu->regs->trapnum = 256;
|
|
|
|
/*
|
|
* Now: we push the "eflags" register on the stack, then do an "lcall".
|
|
* This is how we change from using the kernel code segment to using
|
|
* the dedicated lguest code segment, as well as jumping into the
|
|
* Switcher.
|
|
*
|
|
* The lcall also pushes the old code segment (KERNEL_CS) onto the
|
|
* stack, then the address of this call. This stack layout happens to
|
|
* exactly match the stack layout created by an interrupt...
|
|
*/
|
|
asm volatile("pushf; lcall *%4"
|
|
/*
|
|
* This is how we tell GCC that %eax ("a") and %ebx ("b")
|
|
* are changed by this routine. The "=" means output.
|
|
*/
|
|
: "=a"(clobber), "=b"(clobber)
|
|
/*
|
|
* %eax contains the pages pointer. ("0" refers to the
|
|
* 0-th argument above, ie "a"). %ebx contains the
|
|
* physical address of the Guest's top-level page
|
|
* directory.
|
|
*/
|
|
: "0"(pages),
|
|
"1"(__pa(cpu->lg->pgdirs[cpu->cpu_pgd].pgdir)),
|
|
"m"(lguest_entry)
|
|
/*
|
|
* We tell gcc that all these registers could change,
|
|
* which means we don't have to save and restore them in
|
|
* the Switcher.
|
|
*/
|
|
: "memory", "%edx", "%ecx", "%edi", "%esi");
|
|
}
|
|
/*:*/
|
|
|
|
unsigned long *lguest_arch_regptr(struct lg_cpu *cpu, size_t reg_off, bool any)
|
|
{
|
|
switch (reg_off) {
|
|
case offsetof(struct pt_regs, bx):
|
|
return &cpu->regs->ebx;
|
|
case offsetof(struct pt_regs, cx):
|
|
return &cpu->regs->ecx;
|
|
case offsetof(struct pt_regs, dx):
|
|
return &cpu->regs->edx;
|
|
case offsetof(struct pt_regs, si):
|
|
return &cpu->regs->esi;
|
|
case offsetof(struct pt_regs, di):
|
|
return &cpu->regs->edi;
|
|
case offsetof(struct pt_regs, bp):
|
|
return &cpu->regs->ebp;
|
|
case offsetof(struct pt_regs, ax):
|
|
return &cpu->regs->eax;
|
|
case offsetof(struct pt_regs, ip):
|
|
return &cpu->regs->eip;
|
|
case offsetof(struct pt_regs, sp):
|
|
return &cpu->regs->esp;
|
|
}
|
|
|
|
/* Launcher can read these, but we don't allow any setting. */
|
|
if (any) {
|
|
switch (reg_off) {
|
|
case offsetof(struct pt_regs, ds):
|
|
return &cpu->regs->ds;
|
|
case offsetof(struct pt_regs, es):
|
|
return &cpu->regs->es;
|
|
case offsetof(struct pt_regs, fs):
|
|
return &cpu->regs->fs;
|
|
case offsetof(struct pt_regs, gs):
|
|
return &cpu->regs->gs;
|
|
case offsetof(struct pt_regs, cs):
|
|
return &cpu->regs->cs;
|
|
case offsetof(struct pt_regs, flags):
|
|
return &cpu->regs->eflags;
|
|
case offsetof(struct pt_regs, ss):
|
|
return &cpu->regs->ss;
|
|
}
|
|
}
|
|
|
|
return NULL;
|
|
}
|
|
|
|
/*M:002
|
|
* There are hooks in the scheduler which we can register to tell when we
|
|
* get kicked off the CPU (preempt_notifier_register()). This would allow us
|
|
* to lazily disable SYSENTER which would regain some performance, and should
|
|
* also simplify copy_in_guest_info(). Note that we'd still need to restore
|
|
* things when we exit to Launcher userspace, but that's fairly easy.
|
|
*
|
|
* We could also try using these hooks for PGE, but that might be too expensive.
|
|
*
|
|
* The hooks were designed for KVM, but we can also put them to good use.
|
|
:*/
|
|
|
|
/*H:040
|
|
* This is the i386-specific code to setup and run the Guest. Interrupts
|
|
* are disabled: we own the CPU.
|
|
*/
|
|
void lguest_arch_run_guest(struct lg_cpu *cpu)
|
|
{
|
|
/*
|
|
* Remember the awfully-named TS bit? If the Guest has asked to set it
|
|
* we set it now, so we can trap and pass that trap to the Guest if it
|
|
* uses the FPU.
|
|
*/
|
|
if (cpu->ts && fpregs_active())
|
|
stts();
|
|
|
|
/*
|
|
* SYSENTER is an optimized way of doing system calls. We can't allow
|
|
* it because it always jumps to privilege level 0. A normal Guest
|
|
* won't try it because we don't advertise it in CPUID, but a malicious
|
|
* Guest (or malicious Guest userspace program) could, so we tell the
|
|
* CPU to disable it before running the Guest.
|
|
*/
|
|
if (boot_cpu_has(X86_FEATURE_SEP))
|
|
wrmsr(MSR_IA32_SYSENTER_CS, 0, 0);
|
|
|
|
/*
|
|
* Now we actually run the Guest. It will return when something
|
|
* interesting happens, and we can examine its registers to see what it
|
|
* was doing.
|
|
*/
|
|
run_guest_once(cpu, lguest_pages(raw_smp_processor_id()));
|
|
|
|
/*
|
|
* Note that the "regs" structure contains two extra entries which are
|
|
* not really registers: a trap number which says what interrupt or
|
|
* trap made the switcher code come back, and an error code which some
|
|
* traps set.
|
|
*/
|
|
|
|
/* Restore SYSENTER if it's supposed to be on. */
|
|
if (boot_cpu_has(X86_FEATURE_SEP))
|
|
wrmsr(MSR_IA32_SYSENTER_CS, __KERNEL_CS, 0);
|
|
|
|
/* Clear the host TS bit if it was set above. */
|
|
if (cpu->ts && fpregs_active())
|
|
clts();
|
|
|
|
/*
|
|
* If the Guest page faulted, then the cr2 register will tell us the
|
|
* bad virtual address. We have to grab this now, because once we
|
|
* re-enable interrupts an interrupt could fault and thus overwrite
|
|
* cr2, or we could even move off to a different CPU.
|
|
*/
|
|
if (cpu->regs->trapnum == 14)
|
|
cpu->arch.last_pagefault = read_cr2();
|
|
/*
|
|
* Similarly, if we took a trap because the Guest used the FPU,
|
|
* we have to restore the FPU it expects to see.
|
|
* fpu__restore() may sleep and we may even move off to
|
|
* a different CPU. So all the critical stuff should be done
|
|
* before this.
|
|
*/
|
|
else if (cpu->regs->trapnum == 7 && !fpregs_active())
|
|
fpu__restore(¤t->thread.fpu);
|
|
}
|
|
|
|
/*H:130
|
|
* Now we've examined the hypercall code; our Guest can make requests.
|
|
* Our Guest is usually so well behaved; it never tries to do things it isn't
|
|
* allowed to, and uses hypercalls instead. Unfortunately, Linux's paravirtual
|
|
* infrastructure isn't quite complete, because it doesn't contain replacements
|
|
* for the Intel I/O instructions. As a result, the Guest sometimes fumbles
|
|
* across one during the boot process as it probes for various things which are
|
|
* usually attached to a PC.
|
|
*
|
|
* When the Guest uses one of these instructions, we get a trap (General
|
|
* Protection Fault) and come here. We queue this to be sent out to the
|
|
* Launcher to handle.
|
|
*/
|
|
|
|
/*
|
|
* The eip contains the *virtual* address of the Guest's instruction:
|
|
* we copy the instruction here so the Launcher doesn't have to walk
|
|
* the page tables to decode it. We handle the case (eg. in a kernel
|
|
* module) where the instruction is over two pages, and the pages are
|
|
* virtually but not physically contiguous.
|
|
*
|
|
* The longest possible x86 instruction is 15 bytes, but we don't handle
|
|
* anything that strange.
|
|
*/
|
|
static void copy_from_guest(struct lg_cpu *cpu,
|
|
void *dst, unsigned long vaddr, size_t len)
|
|
{
|
|
size_t to_page_end = PAGE_SIZE - (vaddr % PAGE_SIZE);
|
|
unsigned long paddr;
|
|
|
|
BUG_ON(len > PAGE_SIZE);
|
|
|
|
/* If it goes over a page, copy in two parts. */
|
|
if (len > to_page_end) {
|
|
/* But make sure the next page is mapped! */
|
|
if (__guest_pa(cpu, vaddr + to_page_end, &paddr))
|
|
copy_from_guest(cpu, dst + to_page_end,
|
|
vaddr + to_page_end,
|
|
len - to_page_end);
|
|
else
|
|
/* Otherwise fill with zeroes. */
|
|
memset(dst + to_page_end, 0, len - to_page_end);
|
|
len = to_page_end;
|
|
}
|
|
|
|
/* This will kill the guest if it isn't mapped, but that
|
|
* shouldn't happen. */
|
|
__lgread(cpu, dst, guest_pa(cpu, vaddr), len);
|
|
}
|
|
|
|
|
|
static void setup_emulate_insn(struct lg_cpu *cpu)
|
|
{
|
|
cpu->pending.trap = 13;
|
|
copy_from_guest(cpu, cpu->pending.insn, cpu->regs->eip,
|
|
sizeof(cpu->pending.insn));
|
|
}
|
|
|
|
static void setup_iomem_insn(struct lg_cpu *cpu, unsigned long iomem_addr)
|
|
{
|
|
cpu->pending.trap = 14;
|
|
cpu->pending.addr = iomem_addr;
|
|
copy_from_guest(cpu, cpu->pending.insn, cpu->regs->eip,
|
|
sizeof(cpu->pending.insn));
|
|
}
|
|
|
|
/*H:050 Once we've re-enabled interrupts, we look at why the Guest exited. */
|
|
void lguest_arch_handle_trap(struct lg_cpu *cpu)
|
|
{
|
|
unsigned long iomem_addr;
|
|
|
|
switch (cpu->regs->trapnum) {
|
|
case 13: /* We've intercepted a General Protection Fault. */
|
|
/* Hand to Launcher to emulate those pesky IN and OUT insns */
|
|
if (cpu->regs->errcode == 0) {
|
|
setup_emulate_insn(cpu);
|
|
return;
|
|
}
|
|
break;
|
|
case 14: /* We've intercepted a Page Fault. */
|
|
/*
|
|
* The Guest accessed a virtual address that wasn't mapped.
|
|
* This happens a lot: we don't actually set up most of the page
|
|
* tables for the Guest at all when we start: as it runs it asks
|
|
* for more and more, and we set them up as required. In this
|
|
* case, we don't even tell the Guest that the fault happened.
|
|
*
|
|
* The errcode tells whether this was a read or a write, and
|
|
* whether kernel or userspace code.
|
|
*/
|
|
if (demand_page(cpu, cpu->arch.last_pagefault,
|
|
cpu->regs->errcode, &iomem_addr))
|
|
return;
|
|
|
|
/* Was this an access to memory mapped IO? */
|
|
if (iomem_addr) {
|
|
/* Tell Launcher, let it handle it. */
|
|
setup_iomem_insn(cpu, iomem_addr);
|
|
return;
|
|
}
|
|
|
|
/*
|
|
* OK, it's really not there (or not OK): the Guest needs to
|
|
* know. We write out the cr2 value so it knows where the
|
|
* fault occurred.
|
|
*
|
|
* Note that if the Guest were really messed up, this could
|
|
* happen before it's done the LHCALL_LGUEST_INIT hypercall, so
|
|
* lg->lguest_data could be NULL
|
|
*/
|
|
if (cpu->lg->lguest_data &&
|
|
put_user(cpu->arch.last_pagefault,
|
|
&cpu->lg->lguest_data->cr2))
|
|
kill_guest(cpu, "Writing cr2");
|
|
break;
|
|
case 7: /* We've intercepted a Device Not Available fault. */
|
|
/*
|
|
* If the Guest doesn't want to know, we already restored the
|
|
* Floating Point Unit, so we just continue without telling it.
|
|
*/
|
|
if (!cpu->ts)
|
|
return;
|
|
break;
|
|
case 32 ... 255:
|
|
/*
|
|
* These values mean a real interrupt occurred, in which case
|
|
* the Host handler has already been run. We just do a
|
|
* friendly check if another process should now be run, then
|
|
* return to run the Guest again.
|
|
*/
|
|
cond_resched();
|
|
return;
|
|
case LGUEST_TRAP_ENTRY:
|
|
/*
|
|
* Our 'struct hcall_args' maps directly over our regs: we set
|
|
* up the pointer now to indicate a hypercall is pending.
|
|
*/
|
|
cpu->hcall = (struct hcall_args *)cpu->regs;
|
|
return;
|
|
}
|
|
|
|
/* We didn't handle the trap, so it needs to go to the Guest. */
|
|
if (!deliver_trap(cpu, cpu->regs->trapnum))
|
|
/*
|
|
* If the Guest doesn't have a handler (either it hasn't
|
|
* registered any yet, or it's one of the faults we don't let
|
|
* it handle), it dies with this cryptic error message.
|
|
*/
|
|
kill_guest(cpu, "unhandled trap %li at %#lx (%#lx)",
|
|
cpu->regs->trapnum, cpu->regs->eip,
|
|
cpu->regs->trapnum == 14 ? cpu->arch.last_pagefault
|
|
: cpu->regs->errcode);
|
|
}
|
|
|
|
/*
|
|
* Now we can look at each of the routines this calls, in increasing order of
|
|
* complexity: do_hypercalls(), emulate_insn(), maybe_do_interrupt(),
|
|
* deliver_trap() and demand_page(). After all those, we'll be ready to
|
|
* examine the Switcher, and our philosophical understanding of the Host/Guest
|
|
* duality will be complete.
|
|
:*/
|
|
static void adjust_pge(void *on)
|
|
{
|
|
if (on)
|
|
cr4_set_bits(X86_CR4_PGE);
|
|
else
|
|
cr4_clear_bits(X86_CR4_PGE);
|
|
}
|
|
|
|
/*H:020
|
|
* Now the Switcher is mapped and every thing else is ready, we need to do
|
|
* some more i386-specific initialization.
|
|
*/
|
|
void __init lguest_arch_host_init(void)
|
|
{
|
|
int i;
|
|
|
|
/*
|
|
* Most of the x86/switcher_32.S doesn't care that it's been moved; on
|
|
* Intel, jumps are relative, and it doesn't access any references to
|
|
* external code or data.
|
|
*
|
|
* The only exception is the interrupt handlers in switcher.S: their
|
|
* addresses are placed in a table (default_idt_entries), so we need to
|
|
* update the table with the new addresses. switcher_offset() is a
|
|
* convenience function which returns the distance between the
|
|
* compiled-in switcher code and the high-mapped copy we just made.
|
|
*/
|
|
for (i = 0; i < IDT_ENTRIES; i++)
|
|
default_idt_entries[i] += switcher_offset();
|
|
|
|
/*
|
|
* Set up the Switcher's per-cpu areas.
|
|
*
|
|
* Each CPU gets two pages of its own within the high-mapped region
|
|
* (aka. "struct lguest_pages"). Much of this can be initialized now,
|
|
* but some depends on what Guest we are running (which is set up in
|
|
* copy_in_guest_info()).
|
|
*/
|
|
for_each_possible_cpu(i) {
|
|
/* lguest_pages() returns this CPU's two pages. */
|
|
struct lguest_pages *pages = lguest_pages(i);
|
|
/* This is a convenience pointer to make the code neater. */
|
|
struct lguest_ro_state *state = &pages->state;
|
|
|
|
/*
|
|
* The Global Descriptor Table: the Host has a different one
|
|
* for each CPU. We keep a descriptor for the GDT which says
|
|
* where it is and how big it is (the size is actually the last
|
|
* byte, not the size, hence the "-1").
|
|
*/
|
|
state->host_gdt_desc.size = GDT_SIZE-1;
|
|
state->host_gdt_desc.address = (long)get_cpu_gdt_table(i);
|
|
|
|
/*
|
|
* All CPUs on the Host use the same Interrupt Descriptor
|
|
* Table, so we just use store_idt(), which gets this CPU's IDT
|
|
* descriptor.
|
|
*/
|
|
store_idt(&state->host_idt_desc);
|
|
|
|
/*
|
|
* The descriptors for the Guest's GDT and IDT can be filled
|
|
* out now, too. We copy the GDT & IDT into ->guest_gdt and
|
|
* ->guest_idt before actually running the Guest.
|
|
*/
|
|
state->guest_idt_desc.size = sizeof(state->guest_idt)-1;
|
|
state->guest_idt_desc.address = (long)&state->guest_idt;
|
|
state->guest_gdt_desc.size = sizeof(state->guest_gdt)-1;
|
|
state->guest_gdt_desc.address = (long)&state->guest_gdt;
|
|
|
|
/*
|
|
* We know where we want the stack to be when the Guest enters
|
|
* the Switcher: in pages->regs. The stack grows upwards, so
|
|
* we start it at the end of that structure.
|
|
*/
|
|
state->guest_tss.sp0 = (long)(&pages->regs + 1);
|
|
/*
|
|
* And this is the GDT entry to use for the stack: we keep a
|
|
* couple of special LGUEST entries.
|
|
*/
|
|
state->guest_tss.ss0 = LGUEST_DS;
|
|
|
|
/*
|
|
* x86 can have a finegrained bitmap which indicates what I/O
|
|
* ports the process can use. We set it to the end of our
|
|
* structure, meaning "none".
|
|
*/
|
|
state->guest_tss.io_bitmap_base = sizeof(state->guest_tss);
|
|
|
|
/*
|
|
* Some GDT entries are the same across all Guests, so we can
|
|
* set them up now.
|
|
*/
|
|
setup_default_gdt_entries(state);
|
|
/* Most IDT entries are the same for all Guests, too.*/
|
|
setup_default_idt_entries(state, default_idt_entries);
|
|
|
|
/*
|
|
* The Host needs to be able to use the LGUEST segments on this
|
|
* CPU, too, so put them in the Host GDT.
|
|
*/
|
|
get_cpu_gdt_table(i)[GDT_ENTRY_LGUEST_CS] = FULL_EXEC_SEGMENT;
|
|
get_cpu_gdt_table(i)[GDT_ENTRY_LGUEST_DS] = FULL_SEGMENT;
|
|
}
|
|
|
|
/*
|
|
* In the Switcher, we want the %cs segment register to use the
|
|
* LGUEST_CS GDT entry: we've put that in the Host and Guest GDTs, so
|
|
* it will be undisturbed when we switch. To change %cs and jump we
|
|
* need this structure to feed to Intel's "lcall" instruction.
|
|
*/
|
|
lguest_entry.offset = (long)switch_to_guest + switcher_offset();
|
|
lguest_entry.segment = LGUEST_CS;
|
|
|
|
/*
|
|
* Finally, we need to turn off "Page Global Enable". PGE is an
|
|
* optimization where page table entries are specially marked to show
|
|
* they never change. The Host kernel marks all the kernel pages this
|
|
* way because it's always present, even when userspace is running.
|
|
*
|
|
* Lguest breaks this: unbeknownst to the rest of the Host kernel, we
|
|
* switch to the Guest kernel. If you don't disable this on all CPUs,
|
|
* you'll get really weird bugs that you'll chase for two days.
|
|
*
|
|
* I used to turn PGE off every time we switched to the Guest and back
|
|
* on when we return, but that slowed the Switcher down noticibly.
|
|
*/
|
|
|
|
/*
|
|
* We don't need the complexity of CPUs coming and going while we're
|
|
* doing this.
|
|
*/
|
|
get_online_cpus();
|
|
if (cpu_has_pge) { /* We have a broader idea of "global". */
|
|
/* Remember that this was originally set (for cleanup). */
|
|
cpu_had_pge = 1;
|
|
/*
|
|
* adjust_pge is a helper function which sets or unsets the PGE
|
|
* bit on its CPU, depending on the argument (0 == unset).
|
|
*/
|
|
on_each_cpu(adjust_pge, (void *)0, 1);
|
|
/* Turn off the feature in the global feature set. */
|
|
clear_cpu_cap(&boot_cpu_data, X86_FEATURE_PGE);
|
|
}
|
|
put_online_cpus();
|
|
}
|
|
/*:*/
|
|
|
|
void __exit lguest_arch_host_fini(void)
|
|
{
|
|
/* If we had PGE before we started, turn it back on now. */
|
|
get_online_cpus();
|
|
if (cpu_had_pge) {
|
|
set_cpu_cap(&boot_cpu_data, X86_FEATURE_PGE);
|
|
/* adjust_pge's argument "1" means set PGE. */
|
|
on_each_cpu(adjust_pge, (void *)1, 1);
|
|
}
|
|
put_online_cpus();
|
|
}
|
|
|
|
|
|
/*H:122 The i386-specific hypercalls simply farm out to the right functions. */
|
|
int lguest_arch_do_hcall(struct lg_cpu *cpu, struct hcall_args *args)
|
|
{
|
|
switch (args->arg0) {
|
|
case LHCALL_LOAD_GDT_ENTRY:
|
|
load_guest_gdt_entry(cpu, args->arg1, args->arg2, args->arg3);
|
|
break;
|
|
case LHCALL_LOAD_IDT_ENTRY:
|
|
load_guest_idt_entry(cpu, args->arg1, args->arg2, args->arg3);
|
|
break;
|
|
case LHCALL_LOAD_TLS:
|
|
guest_load_tls(cpu, args->arg1);
|
|
break;
|
|
default:
|
|
/* Bad Guest. Bad! */
|
|
return -EIO;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
/*H:126 i386-specific hypercall initialization: */
|
|
int lguest_arch_init_hypercalls(struct lg_cpu *cpu)
|
|
{
|
|
u32 tsc_speed;
|
|
|
|
/*
|
|
* The pointer to the Guest's "struct lguest_data" is the only argument.
|
|
* We check that address now.
|
|
*/
|
|
if (!lguest_address_ok(cpu->lg, cpu->hcall->arg1,
|
|
sizeof(*cpu->lg->lguest_data)))
|
|
return -EFAULT;
|
|
|
|
/*
|
|
* Having checked it, we simply set lg->lguest_data to point straight
|
|
* into the Launcher's memory at the right place and then use
|
|
* copy_to_user/from_user from now on, instead of lgread/write. I put
|
|
* this in to show that I'm not immune to writing stupid
|
|
* optimizations.
|
|
*/
|
|
cpu->lg->lguest_data = cpu->lg->mem_base + cpu->hcall->arg1;
|
|
|
|
/*
|
|
* We insist that the Time Stamp Counter exist and doesn't change with
|
|
* cpu frequency. Some devious chip manufacturers decided that TSC
|
|
* changes could be handled in software. I decided that time going
|
|
* backwards might be good for benchmarks, but it's bad for users.
|
|
*
|
|
* We also insist that the TSC be stable: the kernel detects unreliable
|
|
* TSCs for its own purposes, and we use that here.
|
|
*/
|
|
if (boot_cpu_has(X86_FEATURE_CONSTANT_TSC) && !check_tsc_unstable())
|
|
tsc_speed = tsc_khz;
|
|
else
|
|
tsc_speed = 0;
|
|
if (put_user(tsc_speed, &cpu->lg->lguest_data->tsc_khz))
|
|
return -EFAULT;
|
|
|
|
/* The interrupt code might not like the system call vector. */
|
|
if (!check_syscall_vector(cpu->lg))
|
|
kill_guest(cpu, "bad syscall vector");
|
|
|
|
return 0;
|
|
}
|
|
/*:*/
|
|
|
|
/*L:030
|
|
* Most of the Guest's registers are left alone: we used get_zeroed_page() to
|
|
* allocate the structure, so they will be 0.
|
|
*/
|
|
void lguest_arch_setup_regs(struct lg_cpu *cpu, unsigned long start)
|
|
{
|
|
struct lguest_regs *regs = cpu->regs;
|
|
|
|
/*
|
|
* There are four "segment" registers which the Guest needs to boot:
|
|
* The "code segment" register (cs) refers to the kernel code segment
|
|
* __KERNEL_CS, and the "data", "extra" and "stack" segment registers
|
|
* refer to the kernel data segment __KERNEL_DS.
|
|
*
|
|
* The privilege level is packed into the lower bits. The Guest runs
|
|
* at privilege level 1 (GUEST_PL).
|
|
*/
|
|
regs->ds = regs->es = regs->ss = __KERNEL_DS|GUEST_PL;
|
|
regs->cs = __KERNEL_CS|GUEST_PL;
|
|
|
|
/*
|
|
* The "eflags" register contains miscellaneous flags. Bit 1 (0x002)
|
|
* is supposed to always be "1". Bit 9 (0x200) controls whether
|
|
* interrupts are enabled. We always leave interrupts enabled while
|
|
* running the Guest.
|
|
*/
|
|
regs->eflags = X86_EFLAGS_IF | X86_EFLAGS_FIXED;
|
|
|
|
/*
|
|
* The "Extended Instruction Pointer" register says where the Guest is
|
|
* running.
|
|
*/
|
|
regs->eip = start;
|
|
|
|
/*
|
|
* %esi points to our boot information, at physical address 0, so don't
|
|
* touch it.
|
|
*/
|
|
|
|
/* There are a couple of GDT entries the Guest expects at boot. */
|
|
setup_guest_gdt(cpu);
|
|
}
|