The patch titled
lguest: handle dodgy/non-existent TSC. Host code.
has been added to the -mm tree. Its filename is
lguest-the-host-code-handle-dodgy-non-existent-tsc-host-code.patch
*** Remember to use Documentation/SubmitChecklist when testing your code ***
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: lguest: handle dodgy/non-existent TSC. Host code.
From: Rusty Russell <rusty@xxxxxxxxxxxxxxx>
Lguest currently requires a TSC, which breaks older machines and Matt Mackall
who boots the host with "notsc". In addition, there is no good solution to
changing TSC speeds (informing all the guests about the TSC impending change
before it happens would be a great deal of code and have issues with
disobedient guests).
This patch makes the host determine if the TSC is both constant and stable: if
not, it doesn't tell the guest to use it. We export check_tsc_unstable() for
this.
Signed-off-by: Rusty Russell <rusty@xxxxxxxxxxxxxxx>
Cc: john stultz <johnstul@xxxxxxxxxx>
Cc: Matt Mackall <mpm@xxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
arch/i386/kernel/tsc.c | 3 ++-
drivers/lguest/core.c | 8 --------
drivers/lguest/hypercalls.c | 9 +++++++++
include/asm-i386/tsc.h | 1 +
4 files changed, 12 insertions(+), 9 deletions(-)
diff -puN arch/i386/kernel/tsc.c~lguest-the-host-code-handle-dodgy-non-existent-tsc-host-code arch/i386/kernel/tsc.c
--- a/arch/i386/kernel/tsc.c~lguest-the-host-code-handle-dodgy-non-existent-tsc-host-code
+++ a/arch/i386/kernel/tsc.c
@@ -58,10 +58,11 @@ __setup("notsc", tsc_setup);
*/
static int tsc_unstable;
-static inline int check_tsc_unstable(void)
+int check_tsc_unstable(void)
{
return tsc_unstable;
}
+EXPORT_SYMBOL_GPL(check_tsc_unstable);
unsigned long native_calculate_cpu_khz(void)
{
diff -puN drivers/lguest/core.c~lguest-the-host-code-handle-dodgy-non-existent-tsc-host-code drivers/lguest/core.c
--- a/drivers/lguest/core.c~lguest-the-host-code-handle-dodgy-non-existent-tsc-host-code
+++ a/drivers/lguest/core.c
@@ -332,14 +332,6 @@ int run_guest(struct lguest *lg, unsigne
continue;
}
- /* If the Guest hasn't been told the clock multiplier to use or
- * it's changed, we update it here. */
- if (unlikely(lg->tsc_khz != tsc_khz) && lg->lguest_data) {
- lg->tsc_khz = tsc_khz;
- if (put_user(lg->tsc_khz, &lg->lguest_data->tsc_khz))
- return -EFAULT;
- }
-
local_irq_disable();
/* Even if *we* don't want FPU trap, guest might... */
diff -puN drivers/lguest/hypercalls.c~lguest-the-host-code-handle-dodgy-non-existent-tsc-host-code drivers/lguest/hypercalls.c
--- a/drivers/lguest/hypercalls.c~lguest-the-host-code-handle-dodgy-non-existent-tsc-host-code
+++ a/drivers/lguest/hypercalls.c
@@ -132,12 +132,20 @@ static void do_async_hcalls(struct lgues
static void initialize(struct lguest *lg)
{
+ u32 tsc_speed;
+
if (lg->regs->eax != LHCALL_LGUEST_INIT) {
kill_guest(lg, "hypercall %li before LGUEST_INIT",
lg->regs->eax);
return;
}
+ /* We only tell the guest to use the TSC if it's reliable. */
+ if (boot_cpu_has(X86_FEATURE_CONSTANT_TSC) && !check_tsc_unstable())
+ tsc_speed = tsc_khz;
+ else
+ tsc_speed = 0;
+
lg->lguest_data = (struct lguest_data __user *)lg->regs->edx;
/* We check here so we can simply copy_to_user/from_user */
if (!lguest_address_ok(lg, lg->regs->edx, sizeof(*lg->lguest_data))) {
@@ -148,6 +156,7 @@ static void initialize(struct lguest *lg
|| get_user(lg->noirq_end, &lg->lguest_data->noirq_end)
/* We reserve the top pgd entry. */
|| put_user(4U*1024*1024, &lg->lguest_data->reserve_mem)
+ || put_user(tsc_speed, &lg->lguest_data->tsc_khz)
|| put_user(lg->guestid, &lg->lguest_data->guestid))
kill_guest(lg, "bad guest page %p", lg->lguest_data);
diff -puN include/asm-i386/tsc.h~lguest-the-host-code-handle-dodgy-non-existent-tsc-host-code include/asm-i386/tsc.h
--- a/include/asm-i386/tsc.h~lguest-the-host-code-handle-dodgy-non-existent-tsc-host-code
+++ a/include/asm-i386/tsc.h
@@ -63,6 +63,7 @@ extern void tsc_init(void);
extern void mark_tsc_unstable(char *reason);
extern int unsynchronized_tsc(void);
extern void init_tsc_clocksource(void);
+int check_tsc_unstable(void);
/*
* Boot-time check whether the TSCs are synchronized across
_
Patches currently in -mm which might be from rusty@xxxxxxxxxxxxxxx are
git-kbuild.patch
paravirt-helper-to-disable-all-io-space-fix.patch
mm-clean-up-and-kernelify-shrinker-registration.patch
mm-clean-up-and-kernelify-shrinker-registration-vs-git-nfs.patch
use-menuconfig-objects-ii-module-menu.patch
fix-stop_machine_run-problem-with-naughty-real-time-process.patch
cpu-hotplug-fix-ksoftirqd-termination-on-cpu-hotplug-with-naughty-realtime-process.patch
cpu-hotplug-fix-ksoftirqd-termination-on-cpu-hotplug-with-naughty-realtime-process-fix.patch
modules-remove-modlist_lock.patch
lguest-export-symbols-for-lguest-as-a-module.patch
lguest-the-guest-code.patch
fix-lguest-w-lockdep.patch
lguest-the-guest-code-lguest-fix-tsc-divide-error-0000-boot-crash.patch
lguest-the-host-code.patch
lguest-the-host-code-lguest-vs-clockevents-fix-resume-logic.patch
lguest-the-host-code-handle-dodgy-non-existent-tsc-host-code.patch
lguest-the-asm-offsets.patch
lguest-the-makefile-and-kconfig.patch
lguest-the-console-driver.patch
lguest-the-net-driver.patch
lguest-the-block-driver.patch
lguest-the-documentation-example-launcher.patch
lguest-the-documentation-example-launcher-fix-guests-1g.patch
lguest-handle-dodgy-non-existent-tsc-guest-code.patch
readahead-introduce-pg_readahead.patch
readahead-add-look-ahead-support-to-__do_page_cache_readahead.patch
readahead-min_ra_pages-max_ra_pages-macros.patch
readahead-data-structure-and-routines.patch
readahead-on-demand-readahead-logic.patch
readahead-convert-filemap-invocations.patch
readahead-convert-splice-invocations.patch
readahead-convert-ext3-ext4-invocations.patch
readahead-remove-the-old-algorithm.patch
readahead-move-synchronous-readahead-call-out-of-splice-loop.patch
readahead-pass-real-splice-size.patch
mm-share-pg_readahead-and-pg_reclaim.patch
readahead-split-ondemand-readahead-interface-into-two-functions.patch
readahead-sanify-file_ra_state-names.patch
define-new-percpu-interface-for-shared-data-version-4.patch
use-the-new-percpu-interface-for-shared-data-version-4.patch
mm-clean-up-and-kernelify-shrinker-registration-reiser4.patch
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