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Make hypercalls arch-independent.

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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>
This commit is contained in:
Jes Sorensen 2007-10-22 11:03:31 +10:00 committed by Rusty Russell
parent cc6d4fbcef
commit b410e7b149
6 changed files with 104 additions and 84 deletions
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8
arch/x86/lguest/boot.c
View File

@ -146,10 +146,10 @@ void async_hcall(unsigned long call,
/* Table full, so do normal hcall which will flush table. */
hcall(call, arg1, arg2, arg3);
} else {
lguest_data.hcalls[next_call].eax = call;
lguest_data.hcalls[next_call].edx = arg1;
lguest_data.hcalls[next_call].ebx = arg2;
lguest_data.hcalls[next_call].ecx = arg3;
lguest_data.hcalls[next_call].arg0 = call;
lguest_data.hcalls[next_call].arg1 = arg1;
lguest_data.hcalls[next_call].arg2 = arg2;
lguest_data.hcalls[next_call].arg3 = arg3;
/* Arguments must all be written before we mark it to go */
wmb();
lguest_data.hcall_status[next_call] = 0;

104
drivers/lguest/hypercalls.c
View File

@ -25,17 +25,13 @@
#include <linux/mm.h>
#include <asm/page.h>
#include <asm/pgtable.h>
#include <irq_vectors.h>
#include "lg.h"
/*H:120 This is the core hypercall routine: where the Guest gets what it
* wants. Or gets killed. Or, in the case of LHCALL_CRASH, both.
*
* Remember from the Guest: %eax == which call to make, and the arguments are
* packed into %edx, %ebx and %ecx if needed. */
static void do_hcall(struct lguest *lg, struct lguest_regs *regs)
/*H:120 This is the core hypercall routine: where the Guest gets what it wants.
* Or gets killed. Or, in the case of LHCALL_CRASH, both. */
static void do_hcall(struct lguest *lg, struct hcall_args *args)
{
switch (regs->eax) {
switch (args->arg0) {
case LHCALL_FLUSH_ASYNC:
/* This call does nothing, except by breaking out of the Guest
* it makes us process all the asynchronous hypercalls. */
@ -51,7 +47,7 @@ static void do_hcall(struct lguest *lg, struct lguest_regs *regs)
char msg[128];
/* If the lgread fails, it will call kill_guest() itself; the
* kill_guest() with the message will be ignored. */
lgread(lg, msg, regs->edx, sizeof(msg));
lgread(lg, msg, args->arg1, sizeof(msg));
msg[sizeof(msg)-1] = '\0';
kill_guest(lg, "CRASH: %s", msg);
break;
@ -59,7 +55,7 @@ static void do_hcall(struct lguest *lg, struct lguest_regs *regs)
case LHCALL_FLUSH_TLB:
/* FLUSH_TLB comes in two flavors, depending on the
* argument: */
if (regs->edx)
if (args->arg1)
guest_pagetable_clear_all(lg);
else
guest_pagetable_flush_user(lg);
@ -71,55 +67,47 @@ static void do_hcall(struct lguest *lg, struct lguest_regs *regs)
* it here. This can legitimately fail, since we currently
* place a limit on the number of DMA pools a Guest can have.
* So we return true or false from this call. */
regs->eax = bind_dma(lg, regs->edx, regs->ebx,
regs->ecx >> 8, regs->ecx & 0xFF);
args->arg0 = bind_dma(lg, args->arg1, args->arg2,
args->arg3 >> 8, args->arg3 & 0xFF);
break;
/* All these calls simply pass the arguments through to the right
* routines. */
case LHCALL_SEND_DMA:
send_dma(lg, regs->edx, regs->ebx);
break;
case LHCALL_LOAD_GDT:
load_guest_gdt(lg, regs->edx, regs->ebx);
break;
case LHCALL_LOAD_IDT_ENTRY:
load_guest_idt_entry(lg, regs->edx, regs->ebx, regs->ecx);
send_dma(lg, args->arg1, args->arg2);
break;
case LHCALL_NEW_PGTABLE:
guest_new_pagetable(lg, regs->edx);
guest_new_pagetable(lg, args->arg1);
break;
case LHCALL_SET_STACK:
guest_set_stack(lg, regs->edx, regs->ebx, regs->ecx);
guest_set_stack(lg, args->arg1, args->arg2, args->arg3);
break;
case LHCALL_SET_PTE:
guest_set_pte(lg, regs->edx, regs->ebx, mkgpte(regs->ecx));
guest_set_pte(lg, args->arg1, args->arg2, mkgpte(args->arg3));
break;
case LHCALL_SET_PMD:
guest_set_pmd(lg, regs->edx, regs->ebx);
break;
case LHCALL_LOAD_TLS:
guest_load_tls(lg, regs->edx);
guest_set_pmd(lg, args->arg1, args->arg2);
break;
case LHCALL_SET_CLOCKEVENT:
guest_set_clockevent(lg, regs->edx);
guest_set_clockevent(lg, args->arg1);
break;
case LHCALL_TS:
/* This sets the TS flag, as we saw used in run_guest(). */
lg->ts = regs->edx;
lg->ts = args->arg1;
break;
case LHCALL_HALT:
/* Similarly, this sets the halted flag for run_guest(). */
lg->halted = 1;
break;
default:
kill_guest(lg, "Bad hypercall %li\n", regs->eax);
if (lguest_arch_do_hcall(lg, args))
kill_guest(lg, "Bad hypercall %li\n", args->arg0);
}
}
/*:*/
/* Asynchronous hypercalls are easy: we just look in the array in the Guest's
* "struct lguest_data" and see if there are any new ones marked "ready".
/*H:124 Asynchronous hypercalls are easy: we just look in the array in the
* Guest's "struct lguest_data" to see if any new ones are marked "ready".
*
* We are careful to do these in order: obviously we respect the order the
* Guest put them in the ring, but we also promise the Guest that they will
@ -134,10 +122,9 @@ static void do_async_hcalls(struct lguest *lg)
if (copy_from_user(&st, &lg->lguest_data->hcall_status, sizeof(st)))
return;
/* We process "struct lguest_data"s hcalls[] ring once. */
for (i = 0; i < ARRAY_SIZE(st); i++) {
struct lguest_regs regs;
struct hcall_args args;
/* We remember where we were up to from last time. This makes
* sure that the hypercalls are done in the order the Guest
* places them in the ring. */
@ -152,18 +139,16 @@ static void do_async_hcalls(struct lguest *lg)
if (++lg->next_hcall == LHCALL_RING_SIZE)
lg->next_hcall = 0;
/* We copy the hypercall arguments into a fake register
* structure. This makes life simple for do_hcall(). */
if (get_user(regs.eax, &lg->lguest_data->hcalls[n].eax)
|| get_user(regs.edx, &lg->lguest_data->hcalls[n].edx)
|| get_user(regs.ecx, &lg->lguest_data->hcalls[n].ecx)
|| get_user(regs.ebx, &lg->lguest_data->hcalls[n].ebx)) {
/* Copy the hypercall arguments into a local copy of
* the hcall_args struct. */
if (copy_from_user(&args, &lg->lguest_data->hcalls[n],
sizeof(struct hcall_args))) {
kill_guest(lg, "Fetching async hypercalls");
break;
}
/* Do the hypercall, same as a normal one. */
do_hcall(lg, &regs);
do_hcall(lg, &args);
/* Mark the hypercall done. */
if (put_user(0xFF, &lg->lguest_data->hcall_status[n])) {
@ -182,41 +167,16 @@ static void do_async_hcalls(struct lguest *lg)
* Guest makes a hypercall, we end up here to set things up: */
static void initialize(struct lguest *lg)
{
u32 tsc_speed;
/* You can't do anything until you're initialized. The Guest knows the
* rules, so we're unforgiving here. */
if (lg->regs->eax != LHCALL_LGUEST_INIT) {
kill_guest(lg, "hypercall %li before LGUEST_INIT",
lg->regs->eax);
if (lg->hcall->arg0 != LHCALL_LGUEST_INIT) {
kill_guest(lg, "hypercall %li before INIT", lg->hcall->arg0);
return;
}
/* 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;
/* The pointer to the Guest's "struct lguest_data" is the only
* argument. We check that address now. */
if (!lguest_address_ok(lg, lg->regs->edx, sizeof(*lg->lguest_data))) {
if (lguest_arch_init_hypercalls(lg))
kill_guest(lg, "bad guest page %p", lg->lguest_data);
return;
}
/* 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. */
lg->lguest_data = lg->mem_base + lg->regs->edx;
/* The Guest tells us where we're not to deliver interrupts by putting
* the range of addresses into "struct lguest_data". */
@ -224,8 +184,7 @@ static void initialize(struct lguest *lg)
|| get_user(lg->noirq_end, &lg->lguest_data->noirq_end)
/* We tell the Guest that it can't use the top 4MB of virtual
* addresses used by the Switcher. */
|| put_user(4U*1024*1024, &lg->lguest_data->reserve_mem)
|| put_user(tsc_speed, &lg->lguest_data->tsc_khz))
|| put_user(4U*1024*1024, &lg->lguest_data->reserve_mem))
kill_guest(lg, "bad guest page %p", lg->lguest_data);
/* We write the current time into the Guest's data page once now. */
@ -237,9 +196,6 @@ static void initialize(struct lguest *lg)
* page. */
guest_pagetable_clear_all(lg);
}
/* Now we've examined the hypercall code; our Guest can make requests. There
* is one other way we can do things for the Guest, as we see in
* emulate_insn(). */
/*H:100
* Hypercalls

4
drivers/lguest/lg.h
View File

@ -107,7 +107,7 @@ struct lguest
u8 ss1;
/* If a hypercall was asked for, this points to the arguments. */
struct lguest_regs *hcall;
struct hcall_args *hcall;
/* Do we need to stop what we're doing and return to userspace? */
int break_out;
@ -197,6 +197,8 @@ void lguest_arch_host_init(void);
void lguest_arch_host_fini(void);
void lguest_arch_run_guest(struct lguest *lg);
void lguest_arch_handle_trap(struct lguest *lg);
int lguest_arch_init_hypercalls(struct lguest *lg);
int lguest_arch_do_hcall(struct lguest *lg, struct hcall_args *args);
/* <arch>/switcher.S: */
extern char start_switcher_text[], end_switcher_text[], switch_to_guest[];

62
drivers/lguest/x86/core.c
View File

@ -323,7 +323,9 @@ void lguest_arch_handle_trap(struct lguest *lg)
cond_resched();
return;
case LGUEST_TRAP_ENTRY:
lg->hcall = lg->regs;
/* Our 'struct hcall_args' maps directly over our regs: we set
* up the pointer now to indicate a hypercall is pending. */
lg->hcall = (struct hcall_args *)lg->regs;
return;
}
@ -475,3 +477,61 @@ void __exit lguest_arch_host_fini(void)
}
unlock_cpu_hotplug();
}
/*H:122 The i386-specific hypercalls simply farm out to the right functions. */
int lguest_arch_do_hcall(struct lguest *lg, struct hcall_args *args)
{
switch (args->arg0) {
case LHCALL_LOAD_GDT:
load_guest_gdt(lg, args->arg1, args->arg2);
break;
case LHCALL_LOAD_IDT_ENTRY:
load_guest_idt_entry(lg, args->arg1, args->arg2, args->arg3);
break;
case LHCALL_LOAD_TLS:
guest_load_tls(lg, args->arg1);
break;
default:
/* Bad Guest. Bad! */
return -EIO;
}
return 0;
}
/*H:126 i386-specific hypercall initialization: */
int lguest_arch_init_hypercalls(struct lguest *lg)
{
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(lg, lg->hcall->arg1, sizeof(*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. */
lg->lguest_data = lg->mem_base + lg->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, &lg->lguest_data->tsc_khz))
return -EFAULT;
return 0;
}
/* Now we've examined the hypercall code; our Guest can make requests. There
* is one other way we can do things for the Guest, as we see in
* emulate_insn(). :*/

8
include/asm-x86/lguest_hcall.h
View File

@ -2,6 +2,8 @@
#ifndef _X86_LGUEST_HCALL_H
#define _X86_LGUEST_HCALL_H
#include <asm/hw_irq.h>
#define LHCALL_FLUSH_ASYNC 0
#define LHCALL_LGUEST_INIT 1
#define LHCALL_CRASH 2
@ -59,9 +61,9 @@ void async_hcall(unsigned long call,
#define LGUEST_IRQS (NR_IRQS < 32 ? NR_IRQS: 32)
#define LHCALL_RING_SIZE 64
struct hcall_ring
struct hcall_args
{
u32 eax, edx, ebx, ecx;
/* These map directly onto eax, ebx, ecx, edx in struct lguest_regs */
unsigned long arg0, arg2, arg3, arg1;
};
#endif /* _I386_LGUEST_HCALL_H */

2
include/linux/lguest.h
View File

@ -36,7 +36,7 @@ struct lguest_data
/* 0xFF == done (set by Host), 0 == pending (set by Guest). */
u8 hcall_status[LHCALL_RING_SIZE];
/* The actual registers for the hypercalls. */
struct hcall_ring hcalls[LHCALL_RING_SIZE];
struct hcall_args hcalls[LHCALL_RING_SIZE];
/* Fields initialized by the Host at boot: */
/* Memory not to try to access */