[PULL] lguest and virtio patches

Rusty Russell
2009-03-28T13:12:20Z

The following changes since commit 5d80f8e5a9dc9c9a94d4aeaa567e219a808b8a4a:
Linus Torvalds (1):
Merge git://git.kernel.org/.../davem/net-2.6

are available in the git repository at:

ssh://master.kernel.org/pub/scm/linux/kernel/git/rusty/linux-2.6-lguest-and-virtio.git master

Matias Zabaljauregui (2):
lguest: use KVM hypercalls
lguest: use bool instead of int

Roel Kluin (1):
virtio: fix BAD_RING, START_US and END_USE macros

Rusty Russell (5):
virtio: more neatening of virtio_ring macros.
lguest: fix spurious BUG_ON() on invalid guest stack.
lguest: wire up pte_update/pte_update_defer
lguest: avoid accidental recycling of pgdir pages
lguest: barrier me harder

Documentation/lguest/lguest.c | 7 +++
arch/x86/include/asm/lguest_hcall.h | 25 ++-------
arch/x86/lguest/boot.c | 94 +++++++++++++++++++++++----------
arch/x86/lguest/i386_head.S | 4 +-
drivers/lguest/core.c | 4 +-
drivers/lguest/hypercalls.c | 3 +
drivers/lguest/interrupts_and_traps.c | 28 +++++-----
drivers/lguest/lg.h | 9 ++--
drivers/lguest/lguest_device.c | 4 +-
drivers/lguest/page_tables.c | 38 ++++++++++----
drivers/lguest/segments.c | 2 +-
drivers/lguest/x86/core.c | 62 +++++++++++++++++++++-
drivers/virtio/virtio_ring.c | 22 +++++---
13 files changed, 210 insertions(+), 92 deletions(-)

commit ca98502ca12192f7f1aec0239734458901c4fdd6
Author: Roel Kluin <roel.kluin@gmail.com>
Date: Thu Jan 22 16:42:57 2009 +0100

virtio: fix BAD_RING, START_US and END_USE macros

Impact: cleanup

fix BAD_RING, START_US and END_USE macros

When these macros aren't called with a variable named vq as first
argument, this would result in a build failure.

Signed-off-by: Roel Kluin <roel.kluin@gmail.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

drivers/virtio/virtio_ring.c | 16 ++++++++--------
1 files changed, 8 insertions(+), 8 deletions(-)

commit d8cac090dbf12b5651609776b18446cd984a4d74
Author: Rusty Russell <rusty@rustcorp.com.au>
Date: Sat Mar 28 23:39:16 2009 -0600

virtio: more neatening of virtio_ring macros.

Impact: cleanup

Roel Kluin drew attention to these macros with his patch: here I
neaten them a little further:
1) Add a comment on what START_USE and END_USE are checking,
2) Brackets around _vq in BAD_RING,
3) Neaten formatting for START_USE so it's less than 80 cols.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

drivers/virtio/virtio_ring.c | 12 +++++++++---
1 files changed, 9 insertions(+), 3 deletions(-)

commit ffa4ae2fe9c68fe35d0dbf29a05af5aff392122b
Author: Rusty Russell <rusty@rustcorp.com.au>
Date: Sat Mar 28 23:39:16 2009 -0600

lguest: fix spurious BUG_ON() on invalid guest stack.

Impact: fix crash on misbehaving guest

gpte_addr() contains a BUG_ON(), insisting that the present flag is
set. We need to return before we call it if that isn't the case.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: stable@kernel.org

drivers/lguest/page_tables.c | 4 +++-
1 files changed, 3 insertions(+), 1 deletions(-)

commit bb32d14a9e3efd1578e8ad53286de71a992bb4db
Author: Rusty Russell <rusty@rustcorp.com.au>
Date: Sat Mar 28 23:39:16 2009 -0600

lguest: wire up pte_update/pte_update_defer

Impact: intermittent guest segv/crash fix

I've been seeing random guest bad address crashes and segmentation faults:
bisect led to 4f98a2fee8 (vmscan: split LRU lists into anon & file sets),
but that's a red herring.

It turns out that lguest never hooked up the pte_update/pte_update_defer
calls, so our ptes were not always in sync. After the vmscan commit, the
bug became reproducible; now a fsck in a 64MB guest causes reproducible
pagetable corruption.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: jeremy@xensource.com
Cc: virtualization@lists.osdl.org
Cc: stable@kernel.org

arch/x86/lguest/boot.c | 10 +++++++++-
1 files changed, 9 insertions(+), 1 deletions(-)

commit 754b83efa91a021395c7df119ce53aeb32cce11d
Author: Rusty Russell <rusty@rustcorp.com.au>
Date: Sat Mar 28 23:39:17 2009 -0600

lguest: avoid accidental recycling of pgdir pages

Impact: potential bugfix

In theory, the kernel could reuse the same page as pgdir for a new process
while the hypervisor keeps it cached. This would have undesirable results.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

arch/x86/include/asm/lguest_hcall.h | 1 +
arch/x86/lguest/boot.c | 8 ++++++++
drivers/lguest/hypercalls.c | 3 +++
drivers/lguest/lg.h | 1 +
drivers/lguest/page_tables.c | 16 ++++++++++++++++
5 files changed, 29 insertions(+), 0 deletions(-)

commit b6757ad1aeeefbe439596dc09f23a4fee16c9079
Author: Matias Zabaljauregui <zabaljauregui@gmail.com>
Date: Sat Mar 14 13:37:52 2009 -0200

lguest: use KVM hypercalls

Impact: cleanup

This patch allow us to use KVM hypercalls

Signed-off-by: Matias Zabaljauregui <zabaljauregui at gmail.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

arch/x86/include/asm/lguest_hcall.h | 24 ++--------
arch/x86/lguest/boot.c | 80 ++++++++++++++++++++------------
arch/x86/lguest/i386_head.S | 4 +-
drivers/lguest/interrupts_and_traps.c | 7 ++-
drivers/lguest/lguest_device.c | 4 +-
drivers/lguest/x86/core.c | 62 +++++++++++++++++++++++++-
6 files changed, 123 insertions(+), 58 deletions(-)

commit f8f81b891f9e2bb0e149c6bfb6b153ea72f5d8ab
Author: Matias Zabaljauregui <zabaljauregui@gmail.com>
Date: Wed Mar 18 13:38:35 2009 -0300

lguest: use bool instead of int

Impact: clean up

Rusty told me, some time ago, that he had become a fan of "bool".
So, here are some replacements.

Signed-off-by: Matias Zabaljauregui <zabaljauregui at gmail.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

drivers/lguest/core.c | 4 ++--
drivers/lguest/interrupts_and_traps.c | 21 +++++++++++----------
drivers/lguest/lg.h | 8 ++++----
drivers/lguest/page_tables.c | 18 +++++++++---------
drivers/lguest/segments.c | 2 +-
5 files changed, 27 insertions(+), 26 deletions(-)

commit 89a923c45472749805a9264fb409eb9c3cbad8e2
Author: Rusty Russell <rusty@rustcorp.com.au>
Date: Sat Mar 28 23:39:19 2009 -0600

lguest: barrier me harder

Impact: barrier correctness in example launcher

I doubt either lguest user will complain about performance.

Reported-by: Christoph Hellwig <hch@infradead.org>
Cc: Jens Axboe <jens.axboe@oracle.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

Documentation/lguest/lguest.c | 7 +++++++
1 files changed, 7 insertions(+), 0 deletions(-)

diff --git a/Documentation/lguest/lguest.c b/Documentation/lguest/lguest.c
index f2dbbf3..d36fcc0 100644
--- a/Documentation/lguest/lguest.c
+++ b/Documentation/lguest/lguest.c
@@ -1630,6 +1630,13 @@ static bool service_io(struct device *dev)
}
}

+ /* OK, so we noted that it was pretty poor to use an fdatasync as a
+ * barrier. But Christoph Hellwig points out that we need a sync
+ * *afterwards* as well: "Barriers specify no reordering to the front
+ * or the back." And Jens Axboe confirmed it, so here we are: */
+ if (out->type & VIRTIO_BLK_T_BARRIER)
+ fdatasync(vblk->fd);
+
/* We can't trigger an IRQ, because we're not the Launcher. It does
* that when we tell it we're done. */
add_used(dev->vq, head, wlen);
diff --git a/arch/x86/include/asm/lguest_hcall.h b/arch/x86/include/asm/lguest_hcall.h
index 4389442..93f6cc4 100644
--- a/arch/x86/include/asm/lguest_hcall.h
+++ b/arch/x86/include/asm/lguest_hcall.h
@@ -17,6 +17,7 @@
#define LHCALL_SET_PMD 15
#define LHCALL_LOAD_TLS 16
#define LHCALL_NOTIFY 17
+#define LHCALL_INVALIDATE_PGTABLE 18

#define LGUEST_TRAP_ENTRY 0x1F

@@ -26,36 +27,20 @@

#ifndef __ASSEMBLY__
#include <asm/hw_irq.h>
+#include <asm/kvm_para.h>

/*G:031 But first, how does our Guest contact the Host to ask for privileged
* operations? There are two ways: the direct way is to make a "hypercall",
* to make requests of the Host Itself.
*
- * Our hypercall mechanism uses the highest unused trap code (traps 32 and
- * above are used by real hardware interrupts). Fifteen hypercalls are
+ * We use the KVM hypercall mechanism. Eighteen hypercalls are
* available: the hypercall number is put in the %eax register, and the
- * arguments (when required) are placed in %edx, %ebx and %ecx. If a return
+ * arguments (when required) are placed in %ebx, %ecx and %edx. If a return
* value makes sense, it's returned in %eax.
*
* Grossly invalid calls result in Sudden Death at the hands of the vengeful
* Host, rather than returning failure. This reflects Winston Churchill's
* definition of a gentleman: "someone who is only rude intentionally". */
-static inline unsigned long
-hcall(unsigned long call,
- unsigned long arg1, unsigned long arg2, unsigned long arg3)
-{
- /* "int" is the Intel instruction to trigger a trap. */
- asm volatile("int $" __stringify(LGUEST_TRAP_ENTRY)
- /* The call in %eax (aka "a") might be overwritten */
- : "=a"(call)
- /* The arguments are in %eax, %edx, %ebx & %ecx */
- : "a"(call), "d"(arg1), "b"(arg2), "c"(arg3)
- /* "memory" means this might write somewhere in memory.
- * This isn't true for all calls, but it's safe to tell
- * gcc that it might happen so it doesn't get clever. */
- : "memory");
- return call;
-}
/*:*/

/* Can't use our min() macro here: needs to be a constant */
@@ -64,7 +49,7 @@ hcall(unsigned long call,
#define LHCALL_RING_SIZE 64
struct hcall_args {
/* These map directly onto eax, ebx, ecx, edx in struct lguest_regs */
- unsigned long arg0, arg2, arg3, arg1;
+ unsigned long arg0, arg1, arg2, arg3;
};

#endif /* !__ASSEMBLY__ */
diff --git a/arch/x86/lguest/boot.c b/arch/x86/lguest/boot.c
index 960a8d9..557957a 100644
--- a/arch/x86/lguest/boot.c
+++ b/arch/x86/lguest/boot.c
@@ -107,7 +107,7 @@ static void async_hcall(unsigned long call, unsigned long arg1,
local_irq_save(flags);
if (lguest_data.hcall_status[next_call] != 0xFF) {
/* Table full, so do normal hcall which will flush table. */
- hcall(call, arg1, arg2, arg3);
+ kvm_hypercall3(call, arg1, arg2, arg3);
} else {
lguest_data.hcalls[next_call].arg0 = call;
lguest_data.hcalls[next_call].arg1 = arg1;
@@ -134,13 +134,32 @@ static void async_hcall(unsigned long call, unsigned long arg1,
*
* So, when we're in lazy mode, we call async_hcall() to store the call for
* future processing: */
-static void lazy_hcall(unsigned long call,
+static void lazy_hcall1(unsigned long call,
+ unsigned long arg1)
+{
+ if (paravirt_get_lazy_mode() == PARAVIRT_LAZY_NONE)
+ kvm_hypercall1(call, arg1);
+ else
+ async_hcall(call, arg1, 0, 0);
+}
+
+static void lazy_hcall2(unsigned long call,
+ unsigned long arg1,
+ unsigned long arg2)
+{
+ if (paravirt_get_lazy_mode() == PARAVIRT_LAZY_NONE)
+ kvm_hypercall2(call, arg1, arg2);
+ else
+ async_hcall(call, arg1, arg2, 0);
+}
+
+static void lazy_hcall3(unsigned long call,
unsigned long arg1,
unsigned long arg2,
unsigned long arg3)
{
if (paravirt_get_lazy_mode() == PARAVIRT_LAZY_NONE)
- hcall(call, arg1, arg2, arg3);
+ kvm_hypercall3(call, arg1, arg2, arg3);
else
async_hcall(call, arg1, arg2, arg3);
}
@@ -150,7 +169,7 @@ static void lazy_hcall(unsigned long call,
static void lguest_leave_lazy_mode(void)
{
paravirt_leave_lazy(paravirt_get_lazy_mode());
- hcall(LHCALL_FLUSH_ASYNC, 0, 0, 0);
+ kvm_hypercall0(LHCALL_FLUSH_ASYNC);
}

/*G:033
@@ -224,7 +243,7 @@ static void lguest_write_idt_entry(gate_desc *dt,
/* Keep the local copy up to date. */
native_write_idt_entry(dt, entrynum, g);
/* Tell Host about this new entry. */
- hcall(LHCALL_LOAD_IDT_ENTRY, entrynum, desc[0], desc[1]);
+ kvm_hypercall3(LHCALL_LOAD_IDT_ENTRY, entrynum, desc[0], desc[1]);
}

/* Changing to a different IDT is very rare: we keep the IDT up-to-date every
@@ -236,7 +255,7 @@ static void lguest_load_idt(const struct desc_ptr *desc)
struct desc_struct *idt = (void *)desc->address;

for (i = 0; i < (desc->size+1)/8; i++)
- hcall(LHCALL_LOAD_IDT_ENTRY, i, idt[i].a, idt[i].b);
+ kvm_hypercall3(LHCALL_LOAD_IDT_ENTRY, i, idt[i].a, idt[i].b);
}

/*
@@ -256,8 +275,8 @@ static void lguest_load_idt(const struct desc_ptr *desc)
*/
static void lguest_load_gdt(const struct desc_ptr *desc)
{
- BUG_ON((desc->size+1)/8 != GDT_ENTRIES);
- hcall(LHCALL_LOAD_GDT, __pa(desc->address), GDT_ENTRIES, 0);
+ BUG_ON((desc->size + 1) / 8 != GDT_ENTRIES);
+ kvm_hypercall2(LHCALL_LOAD_GDT, __pa(desc->address), GDT_ENTRIES);
}

/* For a single GDT entry which changes, we do the lazy thing: alter our GDT,
@@ -267,7 +286,7 @@ static void lguest_write_gdt_entry(struct desc_struct *dt, int entrynum,
const void *desc, int type)
{
native_write_gdt_entry(dt, entrynum, desc, type);
- hcall(LHCALL_LOAD_GDT, __pa(dt), GDT_ENTRIES, 0);
+ kvm_hypercall2(LHCALL_LOAD_GDT, __pa(dt), GDT_ENTRIES);
}

/* OK, I lied. There are three "thread local storage" GDT entries which change
@@ -279,7 +298,7 @@ static void lguest_load_tls(struct thread_struct *t, unsigned int cpu)
* can't handle us removing entries we're currently using. So we clear
* the GS register here: if it's needed it'll be reloaded anyway. */
loadsegment(gs, 0);
- lazy_hcall(LHCALL_LOAD_TLS, __pa(&t->tls_array), cpu, 0);
+ lazy_hcall2(LHCALL_LOAD_TLS, __pa(&t->tls_array), cpu);
}

/*G:038 That's enough excitement for now, back to ploughing through each of
@@ -377,7 +396,7 @@ static void lguest_cpuid(unsigned int *ax, unsigned int *bx,
static unsigned long current_cr0;
static void lguest_write_cr0(unsigned long val)
{
- lazy_hcall(LHCALL_TS, val & X86_CR0_TS, 0, 0);
+ lazy_hcall1(LHCALL_TS, val & X86_CR0_TS);
current_cr0 = val;
}

@@ -391,7 +410,7 @@ static unsigned long lguest_read_cr0(void)
* the vowels have been optimized out. */
static void lguest_clts(void)
{
- lazy_hcall(LHCALL_TS, 0, 0, 0);
+ lazy_hcall1(LHCALL_TS, 0);
current_cr0 &= ~X86_CR0_TS;
}

@@ -413,7 +432,7 @@ static bool cr3_changed = false;
static void lguest_write_cr3(unsigned long cr3)
{
lguest_data.pgdir = cr3;
- lazy_hcall(LHCALL_NEW_PGTABLE, cr3, 0, 0);
+ lazy_hcall1(LHCALL_NEW_PGTABLE, cr3);
cr3_changed = true;
}

@@ -485,11 +504,17 @@ static void lguest_write_cr4(unsigned long val)
* into a process' address space. We set the entry then tell the Host the
* toplevel and address this corresponds to. The Guest uses one pagetable per
* process, so we need to tell the Host which one we're changing (mm->pgd). */
+static void lguest_pte_update(struct mm_struct *mm, unsigned long addr,
+ pte_t *ptep)
+{
+ lazy_hcall3(LHCALL_SET_PTE, __pa(mm->pgd), addr, ptep->pte_low);
+}
+
static void lguest_set_pte_at(struct mm_struct *mm, unsigned long addr,
pte_t *ptep, pte_t pteval)
{
*ptep = pteval;
- lazy_hcall(LHCALL_SET_PTE, __pa(mm->pgd), addr, pteval.pte_low);
+ lguest_pte_update(mm, addr, ptep);
}

/* The Guest calls this to set a top-level entry. Again, we set the entry then
@@ -498,8 +523,8 @@ static void lguest_set_pte_at(struct mm_struct *mm, unsigned long addr,
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);
+ lazy_hcall2(LHCALL_SET_PMD, __pa(pmdp) & PAGE_MASK,
+ (__pa(pmdp) & (PAGE_SIZE - 1)) / 4);
}

/* There are a couple of legacy places where the kernel sets a PTE, but we
@@ -515,7 +540,7 @@ static void lguest_set_pte(pte_t *ptep, pte_t pteval)
{
*ptep = pteval;
if (cr3_changed)
- lazy_hcall(LHCALL_FLUSH_TLB, 1, 0, 0);
+ lazy_hcall1(LHCALL_FLUSH_TLB, 1);
}

/* Unfortunately for Lguest, the pv_mmu_ops for page tables were based on
@@ -531,7 +556,7 @@ static void lguest_set_pte(pte_t *ptep, pte_t pteval)
static void lguest_flush_tlb_single(unsigned long addr)
{
/* Simply set it to zero: if it was not, it will fault back in. */
- lazy_hcall(LHCALL_SET_PTE, lguest_data.pgdir, addr, 0);
+ lazy_hcall3(LHCALL_SET_PTE, lguest_data.pgdir, addr, 0);
}

/* This is what happens after the Guest has removed a large number of entries.
@@ -539,7 +564,7 @@ static void lguest_flush_tlb_single(unsigned long addr)
* have changed, ie. virtual addresses below PAGE_OFFSET. */
static void lguest_flush_tlb_user(void)
{
- lazy_hcall(LHCALL_FLUSH_TLB, 0, 0, 0);
+ lazy_hcall1(LHCALL_FLUSH_TLB, 0);
}

/* This is called when the kernel page tables have changed. That's not very
@@ -547,7 +572,14 @@ static void lguest_flush_tlb_user(void)
* slow), so it's worth separating this from the user flushing above. */
static void lguest_flush_tlb_kernel(void)
{
- lazy_hcall(LHCALL_FLUSH_TLB, 1, 0, 0);
+ lazy_hcall1(LHCALL_FLUSH_TLB, 1);
+}
+
+/* This routine is called when a process exits, and we're throwing away the
+ * page table. */
+static void lguest_pgd_free(struct mm_struct *mm, pgd_t *pgd)
+{
+ lazy_hcall1(LHCALL_INVALIDATE_PGTABLE, __pa(pgd));
}

/*
@@ -684,7 +716,7 @@ static int lguest_clockevent_set_next_event(unsigned long delta,
}

/* Please wake us this far in the future. */
- hcall(LHCALL_SET_CLOCKEVENT, delta, 0, 0);
+ kvm_hypercall1(LHCALL_SET_CLOCKEVENT, delta);
return 0;
}

@@ -695,7 +727,7 @@ static void lguest_clockevent_set_mode(enum clock_event_mode mode,
case CLOCK_EVT_MODE_UNUSED:
case CLOCK_EVT_MODE_SHUTDOWN:
/* A 0 argument shuts the clock down. */
- hcall(LHCALL_SET_CLOCKEVENT, 0, 0, 0);
+ kvm_hypercall0(LHCALL_SET_CLOCKEVENT);
break;
case CLOCK_EVT_MODE_ONESHOT:
/* This is what we expect. */
@@ -770,8 +802,8 @@ static void lguest_time_init(void)
static void lguest_load_sp0(struct tss_struct *tss,
struct thread_struct *thread)
{
- lazy_hcall(LHCALL_SET_STACK, __KERNEL_DS|0x1, thread->sp0,
- THREAD_SIZE/PAGE_SIZE);
+ lazy_hcall3(LHCALL_SET_STACK, __KERNEL_DS | 0x1, thread->sp0,
+ THREAD_SIZE / PAGE_SIZE);
}

/* Let's just say, I wouldn't do debugging under a Guest. */
@@ -843,7 +875,7 @@ static struct apic_ops lguest_basic_apic_ops = {
/* STOP! Until an interrupt comes in. */
static void lguest_safe_halt(void)
{
- hcall(LHCALL_HALT, 0, 0, 0);
+ kvm_hypercall0(LHCALL_HALT);
}

/* The SHUTDOWN hypercall takes a string to describe what's happening, and
@@ -853,7 +885,8 @@ static void lguest_safe_halt(void)
* rather than virtual addresses, so we use __pa() here. */
static void lguest_power_off(void)
{
- hcall(LHCALL_SHUTDOWN, __pa("Power down"), LGUEST_SHUTDOWN_POWEROFF, 0);
+ kvm_hypercall2(LHCALL_SHUTDOWN, __pa("Power down"),
+ LGUEST_SHUTDOWN_POWEROFF);
}

/*
@@ -863,7 +896,7 @@ static void lguest_power_off(void)
*/
static int lguest_panic(struct notifier_block *nb, unsigned long l, void *p)
{
- hcall(LHCALL_SHUTDOWN, __pa(p), LGUEST_SHUTDOWN_POWEROFF, 0);
+ kvm_hypercall2(LHCALL_SHUTDOWN, __pa(p), LGUEST_SHUTDOWN_POWEROFF);
/* The hcall won't return, but to keep gcc happy, we're "done". */
return NOTIFY_DONE;
}
@@ -904,7 +937,7 @@ static __init int early_put_chars(u32 vtermno, const char *buf, int count)
len = sizeof(scratch) - 1;
scratch[len] = '\0';
memcpy(scratch, buf, len);
- hcall(LHCALL_NOTIFY, __pa(scratch), 0, 0);
+ kvm_hypercall1(LHCALL_NOTIFY, __pa(scratch));

/* This routine returns the number of bytes actually written. */
return len;
@@ -914,7 +947,7 @@ static __init int early_put_chars(u32 vtermno, const char *buf, int count)
* Launcher to reboot us. */
static void lguest_restart(char *reason)
{
- hcall(LHCALL_SHUTDOWN, __pa(reason), LGUEST_SHUTDOWN_RESTART, 0);
+ kvm_hypercall2(LHCALL_SHUTDOWN, __pa(reason), LGUEST_SHUTDOWN_RESTART);
}

/*G:050
@@ -1034,6 +1067,9 @@ __init void lguest_init(void)
pv_mmu_ops.read_cr3 = lguest_read_cr3;
pv_mmu_ops.lazy_mode.enter = paravirt_enter_lazy_mmu;
pv_mmu_ops.lazy_mode.leave = lguest_leave_lazy_mode;
+ pv_mmu_ops.pte_update = lguest_pte_update;
+ pv_mmu_ops.pte_update_defer = lguest_pte_update;
+ pv_mmu_ops.pgd_free = lguest_pgd_free;

#ifdef CONFIG_X86_LOCAL_APIC
/* apic read/write intercepts */
diff --git a/arch/x86/lguest/i386_head.S b/arch/x86/lguest/i386_head.S
index 10b9bd3..f795419 100644
--- a/arch/x86/lguest/i386_head.S
+++ b/arch/x86/lguest/i386_head.S
@@ -27,8 +27,8 @@ ENTRY(lguest_entry)
/* We make the "initialization" hypercall now to tell the Host about
* us, and also find out where it put our page tables. */
movl $LHCALL_LGUEST_INIT, %eax
- movl $lguest_data - __PAGE_OFFSET, %edx
- int $LGUEST_TRAP_ENTRY
+ movl $lguest_data - __PAGE_OFFSET, %ebx
+ .byte 0x0f,0x01,0xc1 /* KVM_HYPERCALL */

/* Set up the initial stack so we can run C code. */
movl $(init_thread_union+THREAD_SIZE),%esp
diff --git a/drivers/lguest/core.c b/drivers/lguest/core.c
index 60156df..4845fb3 100644
--- a/drivers/lguest/core.c
+++ b/drivers/lguest/core.c
@@ -152,8 +152,8 @@ static void unmap_switcher(void)
* code. We have to check that the range is below the pfn_limit the Launcher
* gave us. We have to make sure that addr + len doesn't give us a false
* positive by overflowing, too. */
-int lguest_address_ok(const struct lguest *lg,
- unsigned long addr, unsigned long len)
+bool lguest_address_ok(const struct lguest *lg,
+ unsigned long addr, unsigned long len)
{
return (addr+len) / PAGE_SIZE < lg->pfn_limit && (addr+len >= addr);
}
diff --git a/drivers/lguest/hypercalls.c b/drivers/lguest/hypercalls.c
index 54d66f0..a160894 100644
--- a/drivers/lguest/hypercalls.c
+++ b/drivers/lguest/hypercalls.c
@@ -92,6 +92,9 @@ static void do_hcall(struct lg_cpu *cpu, struct hcall_args *args)
case LHCALL_NOTIFY:
cpu->pending_notify = args->arg1;
break;
+ case LHCALL_INVALIDATE_PGTABLE:
+ invalidate_pagetable(cpu, args->arg1);
+ break;
default:
/* It should be an architecture-specific hypercall. */
if (lguest_arch_do_hcall(cpu, args))
diff --git a/drivers/lguest/interrupts_and_traps.c b/drivers/lguest/interrupts_and_traps.c
index 415fab0..6e99adb 100644
--- a/drivers/lguest/interrupts_and_traps.c
+++ b/drivers/lguest/interrupts_and_traps.c
@@ -34,7 +34,7 @@ static int idt_type(u32 lo, u32 hi)
}

/* An IDT entry can't be used unless the "present" bit is set. */
-static int idt_present(u32 lo, u32 hi)
+static bool idt_present(u32 lo, u32 hi)
{
return (hi & 0x8000);
}
@@ -60,7 +60,8 @@ static void push_guest_stack(struct lg_cpu *cpu, unsigned long *gstack, u32 val)
* We set up the stack just like the CPU does for a real interrupt, so it's
* identical for the Guest (and the standard "iret" instruction will undo
* it). */
-static void set_guest_interrupt(struct lg_cpu *cpu, u32 lo, u32 hi, int has_err)
+static void set_guest_interrupt(struct lg_cpu *cpu, u32 lo, u32 hi,
+ bool has_err)
{
unsigned long gstack, origstack;
u32 eflags, ss, irq_enable;
@@ -184,7 +185,7 @@ void maybe_do_interrupt(struct lg_cpu *cpu)
/* set_guest_interrupt() takes the interrupt descriptor and a
* flag to say whether this interrupt pushes an error code onto
* the stack as well: virtual interrupts never do. */
- set_guest_interrupt(cpu, idt->a, idt->b, 0);
+ set_guest_interrupt(cpu, idt->a, idt->b, false);
}

/* Every time we deliver an interrupt, we update the timestamp in the
@@ -244,26 +245,26 @@ void free_interrupts(void)
/*H:220 Now we've got the routines to deliver interrupts, delivering traps like
* page fault is easy. The only trick is that Intel decided that some traps
* should have error codes: */
-static int has_err(unsigned int trap)
+static bool has_err(unsigned int trap)
{
return (trap == 8 || (trap >= 10 && trap <= 14) || trap == 17);
}

/* deliver_trap() returns true if it could deliver the trap. */
-int deliver_trap(struct lg_cpu *cpu, unsigned int num)
+bool deliver_trap(struct lg_cpu *cpu, unsigned int num)
{
/* Trap numbers are always 8 bit, but we set an impossible trap number
* for traps inside the Switcher, so check that here. */
if (num >= ARRAY_SIZE(cpu->arch.idt))
- return 0;
+ return false;

/* Early on the Guest hasn't set the IDT entries (or maybe it put a
* bogus one in): if we fail here, the Guest will be killed. */
if (!idt_present(cpu->arch.idt[num].a, cpu->arch.idt[num].b))
- return 0;
+ return false;
set_guest_interrupt(cpu, cpu->arch.idt[num].a,
cpu->arch.idt[num].b, has_err(num));
- return 1;
+ return true;
}

/*H:250 Here's the hard part: returning to the Host every time a trap happens
@@ -279,18 +280,19 @@ int deliver_trap(struct lg_cpu *cpu, unsigned int num)
*
* This routine indicates if a particular trap number could be delivered
* directly. */
-static int direct_trap(unsigned int num)
+static bool direct_trap(unsigned int num)
{
/* Hardware interrupts don't go to the Guest at all (except system
* call). */
if (num >= FIRST_EXTERNAL_VECTOR && !could_be_syscall(num))
- return 0;
+ return false;

/* The Host needs to see page faults (for shadow paging and to save the
* fault address), general protection faults (in/out emulation) and
- * device not available (TS handling), and of course, the hypercall
- * trap. */
- return num != 14 && num != 13 && num != 7 && num != LGUEST_TRAP_ENTRY;
+ * device not available (TS handling), invalid opcode fault (kvm hcall),
+ * and of course, the hypercall trap. */
+ return num != 14 && num != 13 && num != 7 &&
+ num != 6 && num != LGUEST_TRAP_ENTRY;
}
/*:*/

diff --git a/drivers/lguest/lg.h b/drivers/lguest/lg.h
index f2c641e..4d81591 100644
--- a/drivers/lguest/lg.h
+++ b/drivers/lguest/lg.h
@@ -109,8 +109,8 @@ struct lguest
extern struct mutex lguest_lock;

/* core.c: */
-int lguest_address_ok(const struct lguest *lg,
- unsigned long addr, unsigned long len);
+bool lguest_address_ok(const struct lguest *lg,
+ unsigned long addr, unsigned long len);
void __lgread(struct lg_cpu *, void *, unsigned long, unsigned);
void __lgwrite(struct lg_cpu *, unsigned long, const void *, unsigned);

@@ -140,7 +140,7 @@ int run_guest(struct lg_cpu *cpu, unsigned long __user *user);

/* interrupts_and_traps.c: */
void maybe_do_interrupt(struct lg_cpu *cpu);
-int deliver_trap(struct lg_cpu *cpu, unsigned int num);
+bool deliver_trap(struct lg_cpu *cpu, unsigned int num);
void load_guest_idt_entry(struct lg_cpu *cpu, unsigned int i,
u32 low, u32 hi);
void guest_set_stack(struct lg_cpu *cpu, u32 seg, u32 esp, unsigned int pages);
@@ -173,7 +173,8 @@ void guest_pagetable_flush_user(struct lg_cpu *cpu);
void guest_set_pte(struct lg_cpu *cpu, unsigned long gpgdir,
unsigned long vaddr, pte_t val);
void map_switcher_in_guest(struct lg_cpu *cpu, struct lguest_pages *pages);
-int demand_page(struct lg_cpu *cpu, unsigned long cr2, int errcode);
+bool demand_page(struct lg_cpu *cpu, unsigned long cr2, int errcode);
+void invalidate_pagetable(struct lg_cpu *cpu, unsigned long pgtable);
void pin_page(struct lg_cpu *cpu, unsigned long vaddr);
unsigned long guest_pa(struct lg_cpu *cpu, unsigned long vaddr);
void page_table_guest_data_init(struct lg_cpu *cpu);
diff --git a/drivers/lguest/lguest_device.c b/drivers/lguest/lguest_device.c
index 8132533..df44d96 100644
--- a/drivers/lguest/lguest_device.c
+++ b/drivers/lguest/lguest_device.c
@@ -161,7 +161,7 @@ static void set_status(struct virtio_device *vdev, u8 status)

/* We set the status. */
to_lgdev(vdev)->desc->status = status;
- hcall(LHCALL_NOTIFY, (max_pfn<<PAGE_SHIFT) + offset, 0, 0);
+ kvm_hypercall1(LHCALL_NOTIFY, (max_pfn << PAGE_SHIFT) + offset);
}

static void lg_set_status(struct virtio_device *vdev, u8 status)
@@ -209,7 +209,7 @@ static void lg_notify(struct virtqueue *vq)
* virtqueue structure. */
struct lguest_vq_info *lvq = vq->priv;

- hcall(LHCALL_NOTIFY, lvq->config.pfn << PAGE_SHIFT, 0, 0);
+ kvm_hypercall1(LHCALL_NOTIFY, lvq->config.pfn << PAGE_SHIFT);
}

/* An extern declaration inside a C file is bad form. Don't do it. */
diff --git a/drivers/lguest/page_tables.c b/drivers/lguest/page_tables.c
index 576a831..d137f7d 100644
--- a/drivers/lguest/page_tables.c
+++ b/drivers/lguest/page_tables.c
@@ -199,7 +199,7 @@ static void check_gpgd(struct lg_cpu *cpu, pgd_t gpgd)
*
* If we fixed up the fault (ie. we mapped the address), this routine returns
* true. Otherwise, it was a real fault and we need to tell the Guest. */
-int demand_page(struct lg_cpu *cpu, unsigned long vaddr, int errcode)
+bool demand_page(struct lg_cpu *cpu, unsigned long vaddr, int errcode)
{
pgd_t gpgd;
pgd_t *spgd;
@@ -211,7 +211,7 @@ int demand_page(struct lg_cpu *cpu, unsigned long vaddr, int errcode)
gpgd = lgread(cpu, gpgd_addr(cpu, vaddr), pgd_t);
/* Toplevel not present? We can't map it in. */
if (!(pgd_flags(gpgd) & _PAGE_PRESENT))
- return 0;
+ return false;

/* Now look at the matching shadow entry. */
spgd = spgd_addr(cpu, cpu->cpu_pgd, vaddr);
@@ -222,7 +222,7 @@ int demand_page(struct lg_cpu *cpu, unsigned long vaddr, int errcode)
* simple for this corner case. */
if (!ptepage) {
kill_guest(cpu, "out of memory allocating pte page");
- return 0;
+ return false;
}
/* We check that the Guest pgd is OK. */
check_gpgd(cpu, gpgd);
@@ -238,16 +238,16 @@ int demand_page(struct lg_cpu *cpu, unsigned long vaddr, int errcode)

/* If this page isn't in the Guest page tables, we can't page it in. */
if (!(pte_flags(gpte) & _PAGE_PRESENT))
- return 0;
+ return false;

/* Check they're not trying to write to a page the Guest wants
* read-only (bit 2 of errcode == write). */
if ((errcode & 2) && !(pte_flags(gpte) & _PAGE_RW))
- return 0;
+ return false;

/* User access to a kernel-only page? (bit 3 == user access) */
if ((errcode & 4) && !(pte_flags(gpte) & _PAGE_USER))
- return 0;
+ return false;

/* Check that the Guest PTE flags are OK, and the page number is below
* the pfn_limit (ie. not mapping the Launcher binary). */
@@ -283,7 +283,7 @@ int demand_page(struct lg_cpu *cpu, unsigned long vaddr, int errcode)
* manipulated, the result returned and the code complete. A small
* delay and a trace of alliteration are the only indications the Guest
* has that a page fault occurred at all. */
- return 1;
+ return true;
}

/*H:360
@@ -296,7 +296,7 @@ int demand_page(struct lg_cpu *cpu, unsigned long vaddr, int errcode)
*
* This is a quick version which answers the question: is this virtual address
* mapped by the shadow page tables, and is it writable? */
-static int page_writable(struct lg_cpu *cpu, unsigned long vaddr)
+static bool page_writable(struct lg_cpu *cpu, unsigned long vaddr)
{
pgd_t *spgd;
unsigned long flags;
@@ -304,7 +304,7 @@ static int page_writable(struct lg_cpu *cpu, unsigned long vaddr)
/* Look at the current top level entry: is it present? */
spgd = spgd_addr(cpu, cpu->cpu_pgd, vaddr);
if (!(pgd_flags(*spgd) & _PAGE_PRESENT))
- return 0;
+ return false;

/* Check the flags on the pte entry itself: it must be present and
* writable. */
@@ -373,8 +373,10 @@ unsigned long guest_pa(struct lg_cpu *cpu, unsigned long vaddr)
/* First step: get the top-level Guest page table entry. */
gpgd = lgread(cpu, gpgd_addr(cpu, vaddr), pgd_t);
/* Toplevel not present? We can't map it in. */
- if (!(pgd_flags(gpgd) & _PAGE_PRESENT))
+ if (!(pgd_flags(gpgd) & _PAGE_PRESENT)) {
kill_guest(cpu, "Bad address %#lx", vaddr);
+ return -1UL;
+ }

gpte = lgread(cpu, gpte_addr(gpgd, vaddr), pte_t);
if (!(pte_flags(gpte) & _PAGE_PRESENT))
@@ -449,6 +451,22 @@ void guest_new_pagetable(struct lg_cpu *cpu, unsigned long pgtable)
pin_stack_pages(cpu);
}

+/* The Guest tells us when a page is no longer being used as a pagetable.
+ * Without this there can be a subtle bug where the same page gets re-used
+ * for a different process, and we think it's the same one as the one we have
+ * in our little pgdir cache. */
+void invalidate_pagetable(struct lg_cpu *cpu, unsigned long pgtable)
+{
+ unsigned int pgdir = find_pgdir(cpu->lg, pgtable);
+
+ if (pgdir != ARRAY_SIZE(cpu->lg->pgdirs)) {
+ if (pgdir == cpu->cpu_pgd)
+ kill_guest(cpu, "Attempt to invalidate in-use pgdir");
+ /* We set it to an invalid value. */
+ cpu->lg->pgdirs[pgdir].gpgdir = -1UL;
+ }
+}
+
/*H:470 Finally, a routine which throws away everything: all PGD entries in all
* the shadow page tables, including the Guest's kernel mappings. This is used
* when we destroy the Guest. */
diff --git a/drivers/lguest/segments.c b/drivers/lguest/segments.c
index ec6aa3f..4f15439 100644
--- a/drivers/lguest/segments.c
+++ b/drivers/lguest/segments.c
@@ -45,7 +45,7 @@
* "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 int ignored_gdt(unsigned int num)
+static bool ignored_gdt(unsigned int num)
{
return (num == GDT_ENTRY_TSS
|| num == GDT_ENTRY_LGUEST_CS
diff --git a/drivers/lguest/x86/core.c b/drivers/lguest/x86/core.c
index bf79423..a6b7176 100644
--- a/drivers/lguest/x86/core.c
+++ b/drivers/lguest/x86/core.c
@@ -290,6 +290,57 @@ static int emulate_insn(struct lg_cpu *cpu)
return 1;
}

+/* Our hypercalls mechanism used to be based on direct software interrupts.
+ * After Anthony's "Refactor hypercall infrastructure" kvm patch, we decided to
+ * change over to using kvm hypercalls.
+ *
+ * KVM_HYPERCALL is actually a "vmcall" instruction, which generates an invalid
+ * opcode fault (fault 6) on non-VT cpus, so the easiest solution seemed to be
+ * an *emulation approach*: if the fault was really produced by an hypercall
+ * (is_hypercall() does exactly this check), we can just call the corresponding
+ * hypercall host implementation function.
+ *
+ * But these invalid opcode faults are notably slower than software interrupts.
+ * So we implemented the *patching (or rewriting) approach*: every time we hit
+ * the KVM_HYPERCALL opcode in Guest code, we patch it to the old "int 0x1f"
+ * opcode, so next time the Guest calls this hypercall it will use the
+ * faster trap mechanism.
+ *
+ * Matias even benchmarked it to convince you: this shows the average cycle
+ * cost of a hypercall. For each alternative solution mentioned above we've
+ * made 5 runs of the benchmark:
+ *
+ * 1) direct software interrupt: 2915, 2789, 2764, 2721, 2898
+ * 2) emulation technique: 3410, 3681, 3466, 3392, 3780
+ * 3) patching (rewrite) technique: 2977, 2975, 2891, 2637, 2884
+ *
+ * One two-line function is worth a 20% hypercall speed boost!
+ */
+static void rewrite_hypercall(struct lg_cpu *cpu)
+{
+ /* This are the opcodes we use to patch the Guest. The opcode for "int
+ * $0x1f" is "0xcd 0x1f" but vmcall instruction is 3 bytes long, so we
+ * complete the sequence with a NOP (0x90). */
+ u8 insn[3] = {0xcd, 0x1f, 0x90};
+
+ __lgwrite(cpu, guest_pa(cpu, cpu->regs->eip), insn, sizeof(insn));
+}
+
+static bool is_hypercall(struct lg_cpu *cpu)
+{
+ u8 insn[3];
+
+ /* This must be the Guest kernel trying to do something.
+ * The bottom two bits of the CS segment register are the privilege
+ * level. */
+ if ((cpu->regs->cs & 3) != GUEST_PL)
+ return false;
+
+ /* Is it a vmcall? */
+ __lgread(cpu, insn, guest_pa(cpu, cpu->regs->eip), sizeof(insn));
+ return insn[0] == 0x0f && insn[1] == 0x01 && insn[2] == 0xc1;
+}
+
/*H:050 Once we've re-enabled interrupts, we look at why the Guest exited. */
void lguest_arch_handle_trap(struct lg_cpu *cpu)
{
@@ -337,7 +388,7 @@ void lguest_arch_handle_trap(struct lg_cpu *cpu)
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
+ * 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();
@@ -347,6 +398,15 @@ void lguest_arch_handle_trap(struct lg_cpu *cpu)
* up the pointer now to indicate a hypercall is pending. */
cpu->hcall = (struct hcall_args *)cpu->regs;
return;
+ case 6:
+ /* kvm hypercalls trigger an invalid opcode fault (6).
+ * We need to check if ring == GUEST_PL and
+ * faulting instruction == vmcall. */
+ if (is_hypercall(cpu)) {
+ rewrite_hypercall(cpu);
+ return;
+ }
+ break;
}

/* We didn't handle the trap, so it needs to go to the Guest. */
diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index 5777196..5c52369 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -23,15 +23,21 @@

#ifdef DEBUG
/* For development, we want to crash whenever the ring is screwed. */
-#define BAD_RING(vq, fmt...) \
- do { dev_err(&vq->vq.vdev->dev, fmt); BUG(); } while(0)
-#define START_USE(vq) \
- do { if ((vq)->in_use) panic("in_use = %i\n", (vq)->in_use); (vq)->in_use = __LINE__; mb(); } while(0)
-#define END_USE(vq) \
- do { BUG_ON(!(vq)->in_use); (vq)->in_use = 0; mb(); } while(0)
+#define BAD_RING(_vq, fmt...) \
+ do { dev_err(&(_vq)->vq.vdev->dev, fmt); BUG(); } while(0)
+/* Caller is supposed to guarantee no reentry. */
+#define START_USE(_vq) \
+ do { \
+ if ((_vq)->in_use) \
+ panic("in_use = %i\n", (_vq)->in_use); \
+ (_vq)->in_use = __LINE__; \
+ mb(); \
+ } while(0)
+#define END_USE(_vq) \
+ do { BUG_ON(!(_vq)->in_use); (_vq)->in_use = 0; mb(); } while(0)
#else
-#define BAD_RING(vq, fmt...) \
- do { dev_err(&vq->vq.vdev->dev, fmt); (vq)->broken = true; } while(0)
+#define BAD_RING(_vq, fmt...) \
+ do { dev_err(&_vq->vq.vdev->dev, fmt); (_vq)->broken = true; } while(0)
#define START_USE(vq)
#define END_USE(vq)
#endif