| Message ID | 1445996397-32703-4-git-send-email-pbonzini@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Tue, Oct 27, 2015 at 6:39 PM, Paolo Bonzini <pbonzini@redhat.com> wrote: > x86 always calls user_enter and user_exit with interrupt disabled. > Therefore, it is not necessary to check for exceptions, nor to > save/restore the IRQ state, when context tracking functions are > called by guest_enter and guest_exit. > > Use the previously introduced __context_tracking_entry and > __context_tracking_exit. x86 isn't ready for this yet. We could do a quick-and-dirty fix with explicit IRQs-on-and-off much protected by the static key, or we could just wait until I finish the syscall cleanup. I favor the latter, but you're all welcome to do the former and I'll review it. BTW, Frederic, I have a static key patch coming that I think you'll like. I'll send it tomorrow once I'm in front of a real computer. --Andy -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 28/10/2015 06:22, Andy Lutomirski wrote: >> > called by guest_enter and guest_exit. >> > >> > Use the previously introduced __context_tracking_entry and >> > __context_tracking_exit. > x86 isn't ready for this yet. We could do a quick-and-dirty fix with > explicit IRQs-on-and-off much protected by the static key, or we could > just wait until I finish the syscall cleanup. I favor the latter, but > you're all welcome to do the former and I'll review it. Or we could just do save/restore for the only call that doesn't ensure that interrupts are disabled (syscall_trace_phase1 or whatever it's called). But two days from the merge window, I also favor waiting until 4.5. Paolo -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Tue, Oct 27, 2015 at 10:22 PM, Andy Lutomirski <luto@amacapital.net> wrote: > On Tue, Oct 27, 2015 at 6:39 PM, Paolo Bonzini <pbonzini@redhat.com> wrote: >> x86 always calls user_enter and user_exit with interrupt disabled. >> Therefore, it is not necessary to check for exceptions, nor to >> save/restore the IRQ state, when context tracking functions are >> called by guest_enter and guest_exit. >> >> Use the previously introduced __context_tracking_entry and >> __context_tracking_exit. > > x86 isn't ready for this yet. We could do a quick-and-dirty fix with > explicit IRQs-on-and-off much protected by the static key, or we could > just wait until I finish the syscall cleanup. I favor the latter, but > you're all welcome to do the former and I'll review it. > Once Linus pulls tip:x86/asm, x86 should be ready for this. Want to try again? --Andy -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 14/03/2016 20:23, Andy Lutomirski wrote: > On Tue, Oct 27, 2015 at 10:22 PM, Andy Lutomirski <luto@amacapital.net> wrote: >> On Tue, Oct 27, 2015 at 6:39 PM, Paolo Bonzini <pbonzini@redhat.com> wrote: >>> x86 always calls user_enter and user_exit with interrupt disabled. >>> Therefore, it is not necessary to check for exceptions, nor to >>> save/restore the IRQ state, when context tracking functions are >>> called by guest_enter and guest_exit. >>> >>> Use the previously introduced __context_tracking_entry and >>> __context_tracking_exit. >> >> x86 isn't ready for this yet. We could do a quick-and-dirty fix with >> explicit IRQs-on-and-off much protected by the static key, or we could >> just wait until I finish the syscall cleanup. I favor the latter, but >> you're all welcome to do the former and I'll review it. >> > > Once Linus pulls tip:x86/asm, x86 should be ready for this. Want to try again? Yup, it's on my todo list. :) Paolo -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/arch/x86/entry/common.c b/arch/x86/entry/common.c index 80dcc9261ca3..ba707c6da818 100644 --- a/arch/x86/entry/common.c +++ b/arch/x86/entry/common.c @@ -33,7 +33,7 @@ __visible void enter_from_user_mode(void) { CT_WARN_ON(ct_state() != CONTEXT_USER); - user_exit(); + __user_exit(); } #endif @@ -262,7 +262,7 @@ __visible void prepare_exit_to_usermode(struct pt_regs *regs) local_irq_disable(); } - user_enter(); + __user_enter(); } /* diff --git a/include/linux/context_tracking.h b/include/linux/context_tracking.h index 68b575afe5f5..d36a5c8085b7 100644 --- a/include/linux/context_tracking.h +++ b/include/linux/context_tracking.h @@ -19,18 +19,6 @@ extern void context_tracking_exit(enum ctx_state state); extern void context_tracking_user_enter(void); extern void context_tracking_user_exit(void); -static inline void user_enter(void) -{ - if (context_tracking_is_enabled()) - context_tracking_enter(CONTEXT_USER); - -} -static inline void user_exit(void) -{ - if (context_tracking_is_enabled()) - context_tracking_exit(CONTEXT_USER); -} - static inline enum ctx_state exception_enter(void) { enum ctx_state prev_ctx; @@ -67,13 +55,39 @@ static inline enum ctx_state ct_state(void) this_cpu_read(context_tracking.state) : CONTEXT_DISABLED; } #else -static inline void user_enter(void) { } -static inline void user_exit(void) { } +static inline void __context_tracking_enter(enum ctx_state state) { } +static inline void __context_tracking_exit(enum ctx_state state) { } +static inline void context_tracking_enter(enum ctx_state state) { } +static inline void context_tracking_exit(enum ctx_state state) { } static inline enum ctx_state exception_enter(void) { return 0; } static inline void exception_exit(enum ctx_state prev_ctx) { } static inline enum ctx_state ct_state(void) { return CONTEXT_DISABLED; } #endif /* !CONFIG_CONTEXT_TRACKING */ +static inline void __user_enter(void) +{ + if (context_tracking_is_enabled()) + __context_tracking_enter(CONTEXT_USER); + +} +static inline void __user_exit(void) +{ + if (context_tracking_is_enabled()) + __context_tracking_exit(CONTEXT_USER); +} + +static inline void user_enter(void) +{ + if (context_tracking_is_enabled()) + context_tracking_enter(CONTEXT_USER); + +} +static inline void user_exit(void) +{ + if (context_tracking_is_enabled()) + context_tracking_exit(CONTEXT_USER); +} + #define CT_WARN_ON(cond) WARN_ON(context_tracking_is_enabled() && (cond)) #ifdef CONFIG_CONTEXT_TRACKING_FORCE
x86 always calls user_enter and user_exit with interrupt disabled. Therefore, it is not necessary to check for exceptions, nor to save/restore the IRQ state, when context tracking functions are called by guest_enter and guest_exit. Use the previously introduced __context_tracking_entry and __context_tracking_exit. Cc: Andy Lutomirski <luto@kernel.org> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Rik van Riel <riel@redhat.com> Cc: Paul McKenney <paulmck@linux.vnet.ibm.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> --- arch/x86/entry/common.c | 4 ++-- include/linux/context_tracking.h | 42 ++++++++++++++++++++++++++-------------- 2 files changed, 30 insertions(+), 16 deletions(-)