From: Greg KH <gregkh@linuxfoundation.org>
To: Sohil Mehta <sohil.mehta@intel.com>
Cc: x86@kernel.org, Tony Luck <tony.luck@intel.com>,
Dave Hansen <dave.hansen@intel.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
"H . Peter Anvin" <hpa@zytor.com>,
Andy Lutomirski <luto@kernel.org>, Jens Axboe <axboe@kernel.dk>,
Christian Brauner <christian@brauner.io>,
Peter Zijlstra <peterz@infradead.org>,
Shuah Khan <shuah@kernel.org>, Arnd Bergmann <arnd@arndb.de>,
Jonathan Corbet <corbet@lwn.net>, Ashok Raj <ashok.raj@intel.com>,
Jacob Pan <jacob.jun.pan@linux.intel.com>,
Gayatri Kammela <gayatri.kammela@intel.com>,
Zeng Guang <guang.zeng@intel.com>,
Dan Williams <dan.j.williams@intel.com>,
Randy E Witt <randy.e.witt@intel.com>,
Ravi V Shankar <ravi.v.shankar@intel.com>,
Ramesh Thomas <ramesh.thomas@intel.com>,
linux-api@vger.kernel.org, linux-arch@vger.kernel.org,
linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org
Subject: Re: [RFC PATCH 10/13] x86/uintr: Introduce user IPI sender syscalls
Date: Thu, 23 Sep 2021 14:28:25 +0200 [thread overview]
Message-ID: <YUxy6XqMB1+DYJtP@kroah.com> (raw)
In-Reply-To: <20210913200132.3396598-11-sohil.mehta@intel.com>
On Mon, Sep 13, 2021 at 01:01:29PM -0700, Sohil Mehta wrote:
> Add a registration syscall for a task to register itself as a user
> interrupt sender using the uintr_fd generated by the receiver. A task
> can register multiple uintr_fds. Each unique successful connection
> creates a new entry in the User Interrupt Target Table (UITT).
>
> Each entry in the UITT table is referred by the UITT index (uipi_index).
> The uipi_index returned during the registration syscall lets a sender
> generate a user IPI using the 'SENDUIPI <uipi_index>' instruction.
>
> Also, add a sender unregister syscall to unregister a particular task
> from the uintr_fd. Calling close on the uintr_fd will disconnect all
> threads in a sender process from that FD.
>
> Currently, the UITT size is arbitrarily chosen as 256 entries
> corresponding to a 4KB page. Based on feedback and usage data this can
> either be increased/decreased or made dynamic later.
>
> Architecturally, the UITT table can be unique for each thread or shared
> across threads of the same thread group. The current implementation
> keeps the UITT as unique for the each thread. This makes the kernel
> implementation relatively simple and only threads that use uintr get
> setup with the related structures. However, this means that the
> uipi_index for each thread would be inconsistent wrt to other threads.
> (Executing 'SENDUIPI 2' on threads of the same process could generate
> different user interrupts.)
>
> Alternatively, the benefit of sharing the UITT table is that all threads
> would see the same view of the UITT table. Also the kernel UITT memory
> allocation would be more efficient if multiple threads connect to the
> same uintr_fd. However, this would mean the kernel needs to keep the
> UITT table size MISC_MSR[] in sync across these threads. Also the
> UPID/UITT teardown flows might need additional consideration.
>
> Signed-off-by: Sohil Mehta <sohil.mehta@intel.com>
> ---
> arch/x86/include/asm/processor.h | 2 +
> arch/x86/include/asm/uintr.h | 15 ++
> arch/x86/kernel/process.c | 1 +
> arch/x86/kernel/uintr_core.c | 355 ++++++++++++++++++++++++++++++-
> arch/x86/kernel/uintr_fd.c | 133 ++++++++++++
> 5 files changed, 495 insertions(+), 11 deletions(-)
>
> diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
> index d229bfac8b4f..3482c3182e39 100644
> --- a/arch/x86/include/asm/processor.h
> +++ b/arch/x86/include/asm/processor.h
> @@ -10,6 +10,7 @@ struct mm_struct;
> struct io_bitmap;
> struct vm86;
> struct uintr_receiver;
> +struct uintr_sender;
>
> #include <asm/math_emu.h>
> #include <asm/segment.h>
> @@ -533,6 +534,7 @@ struct thread_struct {
> #ifdef CONFIG_X86_USER_INTERRUPTS
> /* User Interrupt state*/
> struct uintr_receiver *ui_recv;
> + struct uintr_sender *ui_send;
> #endif
>
> /* Floating point and extended processor state */
> diff --git a/arch/x86/include/asm/uintr.h b/arch/x86/include/asm/uintr.h
> index 1f00e2a63da4..ef3521dd7fb9 100644
> --- a/arch/x86/include/asm/uintr.h
> +++ b/arch/x86/include/asm/uintr.h
> @@ -8,6 +8,7 @@ struct uintr_upid_ctx {
> struct task_struct *task; /* Receiver task */
> struct uintr_upid *upid;
> refcount_t refs;
> + bool receiver_active; /* Flag for UPID being mapped to a receiver */
> };
>
> struct uintr_receiver_info {
> @@ -16,12 +17,26 @@ struct uintr_receiver_info {
> u64 uvec; /* Vector number */
> };
>
> +struct uintr_sender_info {
> + struct list_head node;
> + struct uintr_uitt_ctx *uitt_ctx;
> + struct task_struct *task;
> + struct uintr_upid_ctx *r_upid_ctx; /* Receiver's UPID context */
> + struct callback_head twork; /* Task work head */
> + unsigned int uitt_index;
> +};
> +
> bool uintr_arch_enabled(void);
> int do_uintr_register_handler(u64 handler);
> int do_uintr_unregister_handler(void);
> int do_uintr_register_vector(struct uintr_receiver_info *r_info);
> void do_uintr_unregister_vector(struct uintr_receiver_info *r_info);
>
> +int do_uintr_register_sender(struct uintr_receiver_info *r_info,
> + struct uintr_sender_info *s_info);
> +void do_uintr_unregister_sender(struct uintr_receiver_info *r_info,
> + struct uintr_sender_info *s_info);
> +
> void uintr_free(struct task_struct *task);
>
> /* TODO: Inline the context switch related functions */
> diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
> index 83677f76bd7b..9db33e467b30 100644
> --- a/arch/x86/kernel/process.c
> +++ b/arch/x86/kernel/process.c
> @@ -92,6 +92,7 @@ int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
> #ifdef CONFIG_X86_USER_INTERRUPTS
> /* User Interrupt state is unique for each task */
> dst->thread.ui_recv = NULL;
> + dst->thread.ui_send = NULL;
> #endif
>
> return fpu_clone(dst);
> diff --git a/arch/x86/kernel/uintr_core.c b/arch/x86/kernel/uintr_core.c
> index 9dcb9f60e5bc..8f331c5fe0cf 100644
> --- a/arch/x86/kernel/uintr_core.c
> +++ b/arch/x86/kernel/uintr_core.c
> @@ -21,6 +21,11 @@
> #include <asm/msr-index.h>
> #include <asm/uintr.h>
>
> +/*
> + * Each UITT entry is 16 bytes in size.
> + * Current UITT table size is set as 4KB (256 * 16 bytes)
> + */
> +#define UINTR_MAX_UITT_NR 256
> #define UINTR_MAX_UVEC_NR 64
>
> /* User Posted Interrupt Descriptor (UPID) */
> @@ -44,6 +49,27 @@ struct uintr_receiver {
> u64 uvec_mask; /* track active vector per bit */
> };
>
> +/* User Interrupt Target Table Entry (UITTE) */
> +struct uintr_uitt_entry {
> + u8 valid; /* bit 0: valid, bit 1-7: reserved */
Do you check that the other bits are set to 0?
> + u8 user_vec;
> + u8 reserved[6];
What is this reserved for?
> + u64 target_upid_addr;
If this is a pointer, why not say it is a pointer?
> +} __packed __aligned(16);
> +
> +struct uintr_uitt_ctx {
> + struct uintr_uitt_entry *uitt;
> + /* Protect UITT */
> + spinlock_t uitt_lock;
> + refcount_t refs;
Again, a kref please.
thanks,
greg k-h
next prev parent reply other threads:[~2021-09-23 12:28 UTC|newest]
Thread overview: 87+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-13 20:01 [RFC PATCH 00/13] x86 User Interrupts support Sohil Mehta
2021-09-13 20:01 ` [RFC PATCH 01/13] x86/uintr/man-page: Include man pages draft for reference Sohil Mehta
2021-09-13 20:01 ` [RFC PATCH 02/13] Documentation/x86: Add documentation for User Interrupts Sohil Mehta
2021-09-13 20:01 ` [RFC PATCH 03/13] x86/cpu: Enumerate User Interrupts support Sohil Mehta
2021-09-23 22:24 ` Thomas Gleixner
2021-09-24 19:59 ` Sohil Mehta
2021-09-27 20:42 ` Sohil Mehta
2021-09-13 20:01 ` [RFC PATCH 04/13] x86/fpu/xstate: Enumerate User Interrupts supervisor state Sohil Mehta
2021-09-23 22:34 ` Thomas Gleixner
2021-09-27 22:25 ` Sohil Mehta
2021-09-13 20:01 ` [RFC PATCH 05/13] x86/irq: Reserve a user IPI notification vector Sohil Mehta
2021-09-23 23:07 ` Thomas Gleixner
2021-09-25 13:30 ` Thomas Gleixner
2021-09-26 12:39 ` Thomas Gleixner
2021-09-27 19:07 ` Sohil Mehta
2021-09-28 8:11 ` Thomas Gleixner
2021-09-27 19:26 ` Sohil Mehta
2021-09-13 20:01 ` [RFC PATCH 06/13] x86/uintr: Introduce uintr receiver syscalls Sohil Mehta
2021-09-23 12:26 ` Greg KH
2021-09-24 0:05 ` Thomas Gleixner
2021-09-27 23:20 ` Sohil Mehta
2021-09-28 4:39 ` Greg KH
2021-09-28 16:47 ` Sohil Mehta
2021-09-23 23:52 ` Thomas Gleixner
2021-09-27 23:57 ` Sohil Mehta
2021-09-13 20:01 ` [RFC PATCH 07/13] x86/process/64: Add uintr task context switch support Sohil Mehta
2021-09-24 0:41 ` Thomas Gleixner
2021-09-28 0:30 ` Sohil Mehta
2021-09-13 20:01 ` [RFC PATCH 08/13] x86/process/64: Clean up uintr task fork and exit paths Sohil Mehta
2021-09-24 1:02 ` Thomas Gleixner
2021-09-28 1:23 ` Sohil Mehta
2021-09-13 20:01 ` [RFC PATCH 09/13] x86/uintr: Introduce vector registration and uintr_fd syscall Sohil Mehta
2021-09-24 10:33 ` Thomas Gleixner
2021-09-28 20:40 ` Sohil Mehta
2021-09-13 20:01 ` [RFC PATCH 10/13] x86/uintr: Introduce user IPI sender syscalls Sohil Mehta
2021-09-23 12:28 ` Greg KH [this message]
2021-09-28 18:01 ` Sohil Mehta
2021-09-29 7:04 ` Greg KH
2021-09-29 14:27 ` Sohil Mehta
2021-09-24 10:54 ` Thomas Gleixner
2021-09-13 20:01 ` [RFC PATCH 11/13] x86/uintr: Introduce uintr_wait() syscall Sohil Mehta
2021-09-24 11:04 ` Thomas Gleixner
2021-09-25 12:08 ` Thomas Gleixner
2021-09-28 23:13 ` Sohil Mehta
2021-09-28 23:08 ` Sohil Mehta
2021-09-26 14:41 ` Thomas Gleixner
2021-09-29 1:09 ` Sohil Mehta
2021-09-29 3:30 ` Andy Lutomirski
2021-09-29 4:56 ` Sohil Mehta
2021-09-30 18:08 ` Andy Lutomirski
2021-09-30 19:29 ` Thomas Gleixner
2021-09-30 22:01 ` Andy Lutomirski
2021-10-01 0:01 ` Thomas Gleixner
2021-10-01 4:41 ` Andy Lutomirski
2021-10-01 9:56 ` Thomas Gleixner
2021-10-01 15:13 ` Andy Lutomirski
2021-10-01 18:04 ` Sohil Mehta
2021-10-01 21:29 ` Thomas Gleixner
2021-10-01 23:00 ` Sohil Mehta
2021-10-01 23:04 ` Andy Lutomirski
2021-09-13 20:01 ` [RFC PATCH 12/13] x86/uintr: Wire up the user interrupt syscalls Sohil Mehta
2021-09-13 20:01 ` [RFC PATCH 13/13] selftests/x86: Add basic tests for User IPI Sohil Mehta
2021-09-13 20:27 ` [RFC PATCH 00/13] x86 User Interrupts support Dave Hansen
2021-09-14 19:03 ` Mehta, Sohil
2021-09-23 12:19 ` Greg KH
2021-09-23 14:09 ` Greg KH
2021-09-23 14:46 ` Dave Hansen
2021-09-23 15:07 ` Greg KH
2021-09-23 23:24 ` Sohil Mehta
2021-09-23 23:09 ` Sohil Mehta
2021-09-24 0:17 ` Sohil Mehta
2021-09-23 14:39 ` Jens Axboe
2021-09-29 4:31 ` Andy Lutomirski
2021-09-30 16:30 ` Stefan Hajnoczi
2021-09-30 17:24 ` Sohil Mehta
2021-09-30 17:26 ` Andy Lutomirski
2021-10-01 16:35 ` Stefan Hajnoczi
2021-10-01 16:41 ` Richard Henderson
2021-09-30 16:26 ` Stefan Hajnoczi
2021-10-01 0:40 ` Sohil Mehta
2021-10-01 8:19 ` Pavel Machek
2021-11-18 22:19 ` Sohil Mehta
2021-11-16 3:49 ` Prakash Sangappa
2021-11-18 21:44 ` Sohil Mehta
2021-12-22 16:17 ` Chrisma Pakha
2022-01-07 2:08 ` Sohil Mehta
2022-01-17 1:14 ` Chrisma Pakha
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