forked from Minki/linux
lguest: suppress interrupts for single insn, not range.
The last patch reduced our interrupt-suppression region to one address, so simplify the code somewhat. Also, remove the obsolete undefined instruction ranges and the comment which refers to lguest_guest.S instead of head_32.S. Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This commit is contained in:
parent
7042cb4eb3
commit
2f921b5bb0
@ -20,13 +20,10 @@ extern unsigned long switcher_addr;
|
||||
/* Found in switcher.S */
|
||||
extern unsigned long default_idt_entries[];
|
||||
|
||||
/* Declarations for definitions in lguest_guest.S */
|
||||
extern char lguest_noirq_start[], lguest_noirq_end[];
|
||||
/* Declarations for definitions in arch/x86/lguest/head_32.S */
|
||||
extern char lguest_noirq_iret[];
|
||||
extern const char lgstart_cli[], lgend_cli[];
|
||||
extern const char lgstart_sti[], lgend_sti[];
|
||||
extern const char lgstart_popf[], lgend_popf[];
|
||||
extern const char lgstart_pushf[], lgend_pushf[];
|
||||
extern const char lgstart_iret[], lgend_iret[];
|
||||
|
||||
extern void lguest_iret(void);
|
||||
extern void lguest_init(void);
|
||||
|
@ -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,
|
||||
|
@ -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
|
||||
@ -174,12 +173,11 @@ ENTRY(lg_restore_fl)
|
||||
*
|
||||
* 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. (It's not necessary to protect pop instruction, since
|
||||
* data gets updated only after it completes, so we end up surrounding
|
||||
* just one instruction, iret).
|
||||
* data gets updated only after it completes, so we only need to protect
|
||||
* one instruction, iret).
|
||||
*/
|
||||
ENTRY(lguest_iret)
|
||||
pushl 2*4(%esp)
|
||||
@ -190,6 +188,5 @@ ENTRY(lguest_iret)
|
||||
* prefix makes sure we use the stack segment, which is still valid.
|
||||
*/
|
||||
popl %ss:lguest_data+LGUEST_DATA_irq_enabled
|
||||
lguest_noirq_start:
|
||||
lguest_noirq_iret:
|
||||
iret
|
||||
lguest_noirq_end:
|
||||
|
@ -211,10 +211,9 @@ static void initialize(struct lg_cpu *cpu)
|
||||
|
||||
/*
|
||||
* The Guest tells us where we're not to deliver interrupts by putting
|
||||
* the range of addresses into "struct lguest_data".
|
||||
* the instruction address into "struct lguest_data".
|
||||
*/
|
||||
if (get_user(cpu->lg->noirq_start, &cpu->lg->lguest_data->noirq_start)
|
||||
|| get_user(cpu->lg->noirq_end, &cpu->lg->lguest_data->noirq_end))
|
||||
if (get_user(cpu->lg->noirq_iret, &cpu->lg->lguest_data->noirq_iret))
|
||||
kill_guest(cpu, "bad guest page %p", cpu->lg->lguest_data);
|
||||
|
||||
/*
|
||||
|
@ -204,8 +204,7 @@ void try_deliver_interrupt(struct lg_cpu *cpu, unsigned int irq, bool more)
|
||||
* They may be in the middle of an iret, where they asked us never to
|
||||
* deliver interrupts.
|
||||
*/
|
||||
if (cpu->regs->eip >= cpu->lg->noirq_start &&
|
||||
(cpu->regs->eip < cpu->lg->noirq_end))
|
||||
if (cpu->regs->eip == cpu->lg->noirq_iret)
|
||||
return;
|
||||
|
||||
/* If they're halted, interrupts restart them. */
|
||||
@ -395,8 +394,9 @@ static bool direct_trap(unsigned int num)
|
||||
* The Guest has the ability to turn its interrupt gates into trap gates,
|
||||
* if it is careful. The Host will let trap gates can go directly to the
|
||||
* Guest, but the Guest needs the interrupts atomically disabled for an
|
||||
* interrupt gate. It can do this by pointing the trap gate at instructions
|
||||
* within noirq_start and noirq_end, where it can safely disable interrupts.
|
||||
* interrupt gate. The Host could provide a mechanism to register more
|
||||
* "no-interrupt" regions, and the Guest could point the trap gate at
|
||||
* instructions within that region, where it can safely disable interrupts.
|
||||
*/
|
||||
|
||||
/*M:006
|
||||
|
@ -102,7 +102,7 @@ struct lguest {
|
||||
|
||||
struct pgdir pgdirs[4];
|
||||
|
||||
unsigned long noirq_start, noirq_end;
|
||||
unsigned long noirq_iret;
|
||||
|
||||
unsigned int stack_pages;
|
||||
u32 tsc_khz;
|
||||
|
@ -61,8 +61,8 @@ struct lguest_data {
|
||||
u32 tsc_khz;
|
||||
|
||||
/* Fields initialized by the Guest at boot: */
|
||||
/* Instruction range to suppress interrupts even if enabled */
|
||||
unsigned long noirq_start, noirq_end;
|
||||
/* Instruction to suppress interrupts even if enabled */
|
||||
unsigned long noirq_iret;
|
||||
/* Address above which page tables are all identical. */
|
||||
unsigned long kernel_address;
|
||||
/* The vector to try to use for system calls (0x40 or 0x80). */
|
||||
|
Loading…
Reference in New Issue
Block a user