Commit Graph

29 Commits

Author SHA1 Message Date
Rusty Russell a6bd8e1303 lguest: comment documentation update.
Took some cycles to re-read the Lguest Journey end-to-end, fix some
rot and tighten some phrases.

Only comments change.  No new jokes, but a couple of recycled old jokes.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2008-03-28 11:05:54 +11:00
Rusty Russell 4357bd9453 lguest: Revert 1ce70c4fac, fix real problem.
Ahmed managed to crash the Host in release_pgd(), which cannot be a Guest
bug, and indeed it wasn't.

The bug was that handing a 0 as the address of the toplevel page table
being manipulated can cause the lookup code in find_pgdir() to return
an uninitialized cache entry (we shadow up to 4 top level page tables
for each Guest).

Commit 37cc8d7f96 introduced this
behaviour in the Guest, uncovering the bug.

The patch which he submitted (which removed the /4 from the index
calculation) simply ensured that these high-indexed entries hit the
early exit path of guest_set_pmd().  But you get lots of segfaults in
guest userspace as the PMDs aren't being updated.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2008-03-11 09:35:58 +11:00
Rusty Russell 3fabc55f34 lguest: Sanitize the lguest clock.
Now the TSC code handles a zero return from calculate_cpu_khz(),
lguest can simply pass through the value it gets from the Host: if
non-zero, all the normal TSC code applies.

Otherwise (or if the Host really doesn't support TSC), the clocksource
code will fall back to the slower but reasonable lguest clock.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2008-03-11 09:35:57 +11:00
Ahmed S. Darwish 1ce70c4fac x86/lguest: fix pgdir pmd index calculation
Hi all,

Beginning from commits close to v2.6.25-rc2, running lguest always oopses
the host kernel. Oops is at [1].

Bisection led to the following commit:

commit 37cc8d7f96

    x86/early_ioremap: don't assume we're using swapper_pg_dir

    At the early stages of boot, before the kernel pagetable has been
    fully initialized, a Xen kernel will still be running off the
    Xen-provided pagetables rather than swapper_pg_dir[].  Therefore,
    readback cr3 to determine the base of the pagetable rather than
    assuming swapper_pg_dir[].

 static inline pmd_t * __init early_ioremap_pmd(unsigned long addr)
 {
-	pgd_t *pgd = &swapper_pg_dir[pgd_index(addr)];
+	/* Don't assume we're using swapper_pg_dir at this point */
+	pgd_t *base = __va(read_cr3());
+	pgd_t *pgd = &base[pgd_index(addr)];
 	pud_t *pud = pud_offset(pgd, addr);
 	pmd_t *pmd = pmd_offset(pud, addr);

Trying to analyze the problem, it seems on the guest side of lguest,
%cr3 has a different value from &swapper_pg-dir (which
is AFAIK fine on a pravirt guest):

Putting some debugging messages in early_ioremap_pmd:

/* Appears 3 times */
[    0.000000] ***************************
[    0.000000] __va(%cr3) = c0000000, &swapper_pg_dir = c02cc000
[    0.000000] ***************************

After 8 hours of debugging and staring on lguest code, I noticed something
strange in paravirt_ops->set_pmd hypercall invocation:

static void lguest_set_pmd(pmd_t *pmdp, pmd_t pmdval)
{
	*pmdp = pmdval;
	lazy_hcall(LHCALL_SET_PMD, __pa(pmdp)&PAGE_MASK,
		   (__pa(pmdp)&(PAGE_SIZE-1))/4, 0);
}

The first hcall parameter is global pgdir which looks fine. The second
parameter is the pmd index in the pgdir which is suspectful.

AFAIK, calculating the index of pmd does not need a divisoin over four.
Removing the division made lguest work fine again . Patch is at [2].

I am not sure why the division over four existed in the first place. It
seems bogus, maybe the Xen patch just made the problem appear ?

[2]: The patch:

[PATCH] lguest: fix pgdir pmd index cacluation

Remove an error in index calculation which leads to removing
a not existing shadow page table (leading to a Null dereference).

Signed-off-by: Ahmed S. Darwish <darwish.07@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-02-26 12:55:49 +01:00
Harvey Harrison cbc3497370 lguest: include function prototypes
Added a declaration to asm-x86/lguest.h and moved the extern arrays there
as well.  As an alternative to including asm/lguest.h directly, an
include could be put in linux/lguest.h

Signed-off-by: Harvey Harrison <harvey.harrison@gmail.com>
Cc: "rusty@rustcorp.com.au" <rusty@rustcorp.com.au>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-02-26 12:55:49 +01:00
Linus Torvalds d145c7253c Merge git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux-2.6-for-linus
* git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux-2.6-for-linus: (27 commits)
  lguest: use __PAGE_KERNEL instead of _PAGE_KERNEL
  lguest: Use explicit includes rateher than indirect
  lguest: get rid of lg variable assignments
  lguest: change gpte_addr header
  lguest: move changed bitmap to lg_cpu
  lguest: move last_pages to lg_cpu
  lguest: change last_guest to last_cpu
  lguest: change spte_addr header
  lguest: per-vcpu lguest pgdir management
  lguest: make pending notifications per-vcpu
  lguest: makes special fields be per-vcpu
  lguest: per-vcpu lguest task management
  lguest: replace lguest_arch with lg_cpu_arch.
  lguest: make registers per-vcpu
  lguest: make emulate_insn receive a vcpu struct.
  lguest: map_switcher_in_guest() per-vcpu
  lguest: per-vcpu interrupt processing.
  lguest: per-vcpu lguest timers
  lguest: make hypercalls use the vcpu struct
  lguest: make write() operation smp aware
  ...

Manual conflict resolved (maybe even correctly, who knows) in
drivers/lguest/x86/core.c
2008-01-31 09:35:32 +11:00
Eduardo Pereira Habkost 42d545c9a4 x86: remove depends on X86_32 from PARAVIRT & PARAVIRT_GUEST
With this, the paravirt_ops code can be enabled on x86_64 also.

Each guest implementation (Xen, VMI, lguest) now depends on X86_32. The
dependencies can be dropped for each one when they start to support
x86_64.

Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-01-30 13:33:32 +01:00
Glauber de Oliveira Costa 014b15be30 x86: change write_gdt_entry signature.
This patch changes the write_gdt_entry function signature.
Instead of the old "a" and "b" parameters, it now receives
a pointer to a desc_struct, and the size of the entry being
handled. This is because x86_64 can have some 16-byte entries
as well as 8-byte ones.

Signed-off-by: Glauber de Oliveira Costa <gcosta@redhat.com>
CC: Zachary Amsden <zach@vmware.com>
CC: Jeremy Fitzhardinge <Jeremy.Fitzhardinge.citrix.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-01-30 13:31:13 +01:00
Glauber de Oliveira Costa 8d947344c4 x86: change write_idt_entry signature
this patch changes write_idt_entry signature. It now takes a gate_desc
instead of the a and b parameters. It will allow it to be later unified
between i386 and x86_64.

Signed-off-by: Glauber de Oliveira Costa <gcosta@redhat.com>
CC: Zachary Amsden <zach@vmware.com>
CC: Jeremy Fitzhardinge <Jeremy.Fitzhardinge.citrix.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-01-30 13:31:12 +01:00
Glauber de Oliveira Costa 6b68f01baa x86: unify struct desc_ptr
This patch unifies struct desc_ptr between i386 and x86_64.
They can be expressed in the exact same way in C code, only
having to change the name of one of them. As Xgt_desc_struct
is ugly and big, this is the one that goes away.

There's also a padding field in i386, but it is not really
needed in the C structure definition.

Signed-off-by: Glauber de Oliveira Costa <gcosta@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-01-30 13:31:12 +01:00
H. Peter Anvin faca62273b x86: use generic register name in the thread and tss structures
This changes size-specific register names (eip/rip, esp/rsp, etc.) to
generic names in the thread and tss structures.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-01-30 13:31:02 +01:00
H. Peter Anvin 65ea5b0349 x86: rename the struct pt_regs members for 32/64-bit consistency
We have a lot of code which differs only by the naming of specific
members of structures that contain registers.  In order to enable
additional unifications, this patch drops the e- or r- size prefix
from the register names in struct pt_regs, and drops the x- prefixes
for segment registers on the 32-bit side.

This patch also performs the equivalent renames in some additional
places that might be candidates for unification in the future.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-01-30 13:30:56 +01:00
Thomas Gleixner 42e0a9aa5d x86: use u32 for some lapic functions
Use u32 so 32 and 64bit have the same interface.

Andrew Morton: xen, lguest build fixes

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-01-30 13:30:15 +01:00
Balaji Rao ec04b13f67 lguest: Reboot support
Reboot Implemented

(Prevent fd leak, fix style and fix documentation --RR)

Signed-off-by: Balaji Rao <balajirrao@gmail.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2008-01-30 22:50:04 +11:00
Randy Dunlap b8415ec34f lguest: prevent VISWS or VOYAGER randconfigs
Keep lguest from being enabled on VISWS or VOYAGER configs, just as is
already done for VMI and XEN.  Otherwise randconfigs with VISWS and LGUEST
have this problem:

In file included from arch/x86/kernel/setup_32.c:61:
include/asm-x86/mach-visws/setup_arch.h:8:1: warning: "ARCH_SETUP" redefined
In file included from include/asm/msr.h:80,
                 from include/asm/processor_32.h:17,
                 from include/asm/processor.h:2,
                 from include/asm/thread_info_32.h:16,
                 from include/asm/thread_info.h:2,
                 from include/linux/thread_info.h:21,
                 from include/linux/preempt.h:9,
                 from include/linux/spinlock.h:49,
                 from include/linux/seqlock.h:29,
                 from include/linux/time.h:8,
                 from include/linux/timex.h:57,
                 from include/linux/sched.h:53,
                 from arch/x86/kernel/setup_32.c:24:
include/asm/paravirt.h:458:1: warning: this is the location of the previous definition

(and of course, this happens because kconfig does not follow dependencies
when [evil] select is used...)

Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-11-29 09:24:55 -08:00
Rusty Russell 633872b980 lguest: tidy up documentation
After Adrian Bunk's "make async_hcall static" moved things around, update
comments to match (aka "make Guest").

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2007-11-05 21:55:57 +11:00
Adrian Bunk 9b56fdb458 lguest: make async_hcall() static
async_hcall() can become static.

Signed-off-by: Adrian Bunk <bunk@kernel.org>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2007-11-05 21:53:29 +11:00
Rusty Russell e1e72965ec lguest: documentation update
Went through the documentation doing typo and content fixes.  This
patch contains only comment and whitespace changes.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2007-10-25 15:02:50 +10:00
Jeff Garzik 4cfe6c3c1c lguest: build fix
Fix this error (i386 !SMP build)

arch/x86/lguest/boot.c: In function ‘lguest_init’:
arch/x86/lguest/boot.c:1059: error: ‘pm_power_off’ undeclared (first use in this function)

by including linux/pm.h.

Signed-off-by: Jeff Garzik <jgarzik@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2007-10-25 14:15:09 +10:00
Rusty Russell 25c47bb353 lguest: use defines from x86 headers instead of magic numbers
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2007-10-25 14:09:53 +10:00
Rusty Russell 814a0e5cdf Revert lguest magic and use hook in head.S
Version 2.07 of the boot protocol uses 0x23C for the hardware_subarch
field, that for lguest is "1".  This allows us to use the standard
boot entry point rather than the "GenuineLguest" string hack.

The standard entry point also clears the BSS and copies the boot parameters
and commandline for us, saving more code.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2007-10-23 15:49:57 +10:00
Rusty Russell 19f1537b7b Lguest support for Virtio
This makes lguest able to use the virtio devices.

We change the device descriptor page from a simple array to a variable
length "type, config_len, status, config data..." format, and
implement virtio_config_ops to read from that config data.

We use the virtio ring implementation for an efficient Guest <-> Host
virtqueue mechanism, and the new LHCALL_NOTIFY hypercall to kick the
host when it changes.

We also use LHCALL_NOTIFY on kernel addresses for very very early
console output.  We could have another hypercall, but this hack works
quite well.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2007-10-23 15:49:56 +10:00
Rusty Russell 0ca49ca946 Remove old lguest bus and drivers.
This gets rid of the lguest bus, drivers and DMA mechanism, to make
way for a generic virtio mechanism.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2007-10-23 15:49:55 +10:00
Rusty Russell 0a8a69dd77 Virtio helper routines for a descriptor ringbuffer implementation
These helper routines supply most of the virtqueue_ops for hypervisors
which want to use a ring for virtio.  Unlike the previous lguest
implementation:

1) The rings are variable sized (2^n-1 elements).
2) They have an unfortunate limit of 65535 bytes per sg element.
3) The page numbers are always 64 bit (PAE anyone?)
4) They no longer place used[] on a separate page, just a separate
   cacheline.
5) We do a modulo on a variable.  We could be tricky if we cared.
6) Interrupts and notifies are suppressed using flags within the rings.

Users need only get the ring pages and provide a notify hook (KVM
wants the guest to allocate the rings, lguest does it sanely).

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: Dor Laor <dor.laor@qumranet.com>
2007-10-23 15:49:55 +10:00
Rusty Russell 47436aa4ad Boot with virtual == physical to get closer to native Linux.
1) This allows us to get alot closer to booting bzImages.

2) It means we don't have to know page_offset.

3) The Guest needs to modify the boot pagetables to create the
   PAGE_OFFSET mapping before jumping to C code.

4) guest_pa() walks the page tables rather than using page_offset.

5) We don't use page_offset to figure out whether to emulate: it was
   always kinda quesationable, and won't work for instructions done
   before remapping (bzImage unpacking in particular).

6) We still want the kernel address for tlb flushing: have the initial
   hypercall give us that, too.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2007-10-23 15:49:54 +10:00
Rusty Russell c18acd73ff Allow guest to specify syscall vector to use.
(Based on Ron Minnich's LGUEST_PLAN9_SYSCALL patch).

This patch allows Guests to specify what system call vector they want,
and we try to reserve it.  We only allow one non-Linux system call
vector, to try to avoid DoS on the Host.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2007-10-23 15:49:53 +10:00
Jes Sorensen b410e7b149 Make hypercalls arch-independent.
Clean up the hypercall code to make the code in hypercalls.c
architecture independent. First process the common hypercalls and
then call lguest_arch_do_hcall() if the call hasn't been handled.
Rename struct hcall_ring to hcall_args.

This patch requires the previous patch which reorganize the layout of
struct lguest_regs on i386 so they match the layout of struct
hcall_args.

Signed-off-by: Jes Sorensen <jes@sgi.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2007-10-23 15:49:52 +10:00
Jes Sorensen 625efab1cd Move i386 part of core.c to x86/core.c.
Separate i386 architecture specific from core.c and move it to
x86/core.c and add x86/lguest.h header file to match.

Signed-off-by: Jes Sorensen <jes@sgi.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2007-10-23 15:49:51 +10:00
Rusty Russell 34b8867a03 Move lguest guest support to arch/x86.
Lguest has two sides: host support (to launch guests) and guest
support (replacement boot path and paravirt_ops).  This moves the
guest side to arch/x86/lguest where it's closer to related code.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: Andi Kleen <ak@suse.de>
2007-10-23 15:49:50 +10:00