summaryrefslogtreecommitdiffstats
path: root/arch/x86/lguest
diff options
context:
space:
mode:
authorLinus Torvalds <torvalds@linux-foundation.org>2015-04-22 10:55:06 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2015-04-22 10:55:06 -0700
commitb9bb6fb73b3e112d241a5edd146740be9a0c3cc0 (patch)
treed65072d0371468d685b7464dc6b38f920c0c9666 /arch/x86/lguest
parent15ce2658ddbd3db20dfba3622f3d224f01837fdc (diff)
parent9abbfb486f5c254805bb6a3f263bc14d989eb90b (diff)
downloadlinux-b9bb6fb73b3e112d241a5edd146740be9a0c3cc0.tar.bz2
Merge tag 'virtio-next-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux
Pull virtio updates from Rusty Russell: "Some virtio internal cleanups, a new virtio device "virtio input", and a change to allow the legacy virtio balloon. Most excitingly, some lguest work! No seriously, I got some cleanup patches" * tag 'virtio-next-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux: virtio: drop virtio_device_is_legacy_only virtio_pci: support non-legacy balloon devices virtio_mmio: support non-legacy balloon devices virtio_ccw: support non-legacy balloon devices virtio: balloon might not be a legacy device virtio_balloon: transitional interface virtio_ring: Update weak barriers to use dma_wmb/rmb virtio_pci_modern: switch to type-safe io accessors virtio_pci_modern: type-safe io accessors lguest: handle traps on the "interrupt suppressed" iret instruction. virtio: drop a useless config read virtio_config: reorder functions Add virtio-input driver. lguest: suppress interrupts for single insn, not range. lguest: simplify lguest_iret lguest: rename i386_head.S in the comments lguest: explicitly set miscdevice's private_data NULL lguest: fix pending interrupt test.
Diffstat (limited to 'arch/x86/lguest')
-rw-r--r--arch/x86/lguest/boot.c7
-rw-r--r--arch/x86/lguest/head_32.S30
2 files changed, 16 insertions, 21 deletions
diff --git a/arch/x86/lguest/boot.c b/arch/x86/lguest/boot.c
index 717908b16037..8f9a133cc099 100644
--- a/arch/x86/lguest/boot.c
+++ b/arch/x86/lguest/boot.c
@@ -87,8 +87,7 @@
struct lguest_data lguest_data = {
.hcall_status = { [0 ... LHCALL_RING_SIZE-1] = 0xFF },
- .noirq_start = (u32)lguest_noirq_start,
- .noirq_end = (u32)lguest_noirq_end,
+ .noirq_iret = (u32)lguest_noirq_iret,
.kernel_address = PAGE_OFFSET,
.blocked_interrupts = { 1 }, /* Block timer interrupts */
.syscall_vec = SYSCALL_VECTOR,
@@ -262,7 +261,7 @@ PV_CALLEE_SAVE_REGS_THUNK(lguest_save_fl);
PV_CALLEE_SAVE_REGS_THUNK(lguest_irq_disable);
/*:*/
-/* These are in i386_head.S */
+/* These are in head_32.S */
extern void lg_irq_enable(void);
extern void lg_restore_fl(unsigned long flags);
@@ -1368,7 +1367,7 @@ static void lguest_restart(char *reason)
* fit comfortably.
*
* First we need assembly templates of each of the patchable Guest operations,
- * and these are in i386_head.S.
+ * and these are in head_32.S.
*/
/*G:060 We construct a table from the assembler templates: */
diff --git a/arch/x86/lguest/head_32.S b/arch/x86/lguest/head_32.S
index 6ddfe4fc23c3..d5ae63f5ec5d 100644
--- a/arch/x86/lguest/head_32.S
+++ b/arch/x86/lguest/head_32.S
@@ -84,7 +84,7 @@ ENTRY(lg_irq_enable)
* set lguest_data.irq_pending to X86_EFLAGS_IF. If it's not zero, we
* jump to send_interrupts, otherwise we're done.
*/
- testl $0, lguest_data+LGUEST_DATA_irq_pending
+ cmpl $0, lguest_data+LGUEST_DATA_irq_pending
jnz send_interrupts
/*
* One cool thing about x86 is that you can do many things without using
@@ -133,9 +133,8 @@ ENTRY(lg_restore_fl)
ret
/*:*/
-/* These demark the EIP range where host should never deliver interrupts. */
-.global lguest_noirq_start
-.global lguest_noirq_end
+/* These demark the EIP where host should never deliver interrupts. */
+.global lguest_noirq_iret
/*M:004
* When the Host reflects a trap or injects an interrupt into the Guest, it
@@ -168,29 +167,26 @@ ENTRY(lg_restore_fl)
* So we have to copy eflags from the stack to lguest_data.irq_enabled before
* we do the "iret".
*
- * There are two problems with this: firstly, we need to use a register to do
- * the copy and secondly, the whole thing needs to be atomic. The first
- * problem is easy to solve: push %eax on the stack so we can use it, and then
- * restore it at the end just before the real "iret".
+ * There are two problems with this: firstly, we can't clobber any registers
+ * and secondly, the whole thing needs to be atomic. The first problem
+ * is solved by using "push memory"/"pop memory" instruction pair for copying.
*
* The second is harder: copying eflags to lguest_data.irq_enabled will turn
* interrupts on before we're finished, so we could be interrupted before we
- * return to userspace or wherever. Our solution to this is to surround the
- * code with lguest_noirq_start: and lguest_noirq_end: labels. We tell the
+ * return to userspace or wherever. Our solution to this is to tell the
* Host that it is *never* to interrupt us there, even if interrupts seem to be
- * enabled.
+ * enabled. (It's not necessary to protect pop instruction, since
+ * data gets updated only after it completes, so we only need to protect
+ * one instruction, iret).
*/
ENTRY(lguest_iret)
- pushl %eax
- movl 12(%esp), %eax
-lguest_noirq_start:
+ pushl 2*4(%esp)
/*
* Note the %ss: segment prefix here. Normal data accesses use the
* "ds" segment, but that will have already been restored for whatever
* we're returning to (such as userspace): we can't trust it. The %ss:
* prefix makes sure we use the stack segment, which is still valid.
*/
- movl %eax,%ss:lguest_data+LGUEST_DATA_irq_enabled
- popl %eax
+ popl %ss:lguest_data+LGUEST_DATA_irq_enabled
+lguest_noirq_iret:
iret
-lguest_noirq_end: