From: Igor Mammedov <imammedo@redhat.com>
To: qemu-devel@nongnu.org
Cc: "Eduardo Habkost" <ehabkost@redhat.com>,
"Michael S. Tsirkin" <mst@redhat.com>,
"Laszlo Ersek" <lersek@redhat.com>,
"Gerd Hoffmann" <kraxel@redhat.com>,
"Paolo Bonzini" <pbonzini@redhat.com>,
"Philippe Mathieu-Daudé" <philmd@redhat.com>,
"Richard Henderson" <rth@twiddle.net>
Subject: [RFC 2/3] acpi: cpuhp: add typical usecases into spec
Date: Wed, 9 Oct 2019 09:22:51 -0400 [thread overview]
Message-ID: <20191009132252.17860-3-imammedo@redhat.com> (raw)
In-Reply-To: <20191009132252.17860-1-imammedo@redhat.com>
Clarify values of "CPU selector' register and add workflows for
* finding CPU with pending 'insert/remove' event
* enumerating present/non present CPUs
Signed-off-by: Igor Mammedov <imammedo@redhat.com>
---
docs/specs/acpi_cpu_hotplug.txt | 22 ++++++++++++++++++++++
1 file changed, 22 insertions(+)
diff --git a/docs/specs/acpi_cpu_hotplug.txt b/docs/specs/acpi_cpu_hotplug.txt
index ac5903b2b1..43c5a193f0 100644
--- a/docs/specs/acpi_cpu_hotplug.txt
+++ b/docs/specs/acpi_cpu_hotplug.txt
@@ -54,6 +54,7 @@ write access:
[0x0-0x3] CPU selector: (DWORD access)
selects active CPU device. All following accesses to other
registers will read/store data from/to selected CPU.
+ Valid values: [0 .. max_cpus)
[0x4] CPU device control fields: (1 byte access)
bits:
0: reserved, OSPM must clear it before writing to register.
@@ -93,3 +94,24 @@ Selecting CPU device beyond possible range has no effect on platform:
ignored
- read accesses to CPU hot-plug registers not documented above return
all bits set to 0.
+
+Typical usecases:
+ - Get a cpu with pending event
+ 1. write 0x0 into 'Command field' register
+ 2. read from 'Command data' register, CPU selector value (CPU's UID in ACPI
+ tables) and event for selected CPU from 'CPU device status fields'
+ register. If there aren't pending events, CPU selector value doesn't
+ change and 'insert' and 'remove' bits are not set.
+ - Enumerate CPUs present/non present CPUs.
+ 1. set iterator to 0x0
+ 2. write 0x0 into 'Command field' register and then iterator
+ into 'CPU selector' register.
+ 3. read 'enabled' flag for selected CPU from 'CPU device status fields'
+ register
+ 4. to continue to the next CPU, increment iterator and repeat step 2
+ 5. read 'Command data' register
+ 5.1 if 'Command data' register matches iterator continue to step 3.
+ (read presence bit for the next CPU)
+ 5.2 if 'Command data' register has not changed, there is not CPU
+ corresponding to iterator value and the last valid iterator value
+ equals to 'max_cpus' + 1
--
2.18.1
next prev parent reply other threads:[~2019-10-09 18:51 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-09 13:22 [RFC 0/3] acpi: cphp: add CPHP_GET_CPU_ID_CMD command to cpu hotplug MMIO interface Igor Mammedov
2019-10-09 13:22 ` [RFC 1/3] acpi: cpuhp: fix 'Command data' description is spec Igor Mammedov
2019-10-10 12:33 ` Laszlo Ersek
2019-10-17 15:41 ` Igor Mammedov
2019-10-18 13:24 ` Laszlo Ersek
2019-10-10 13:31 ` Laszlo Ersek
2019-10-10 13:36 ` Laszlo Ersek
2019-10-22 17:17 ` Christophe de Dinechin
2019-10-22 17:37 ` Laszlo Ersek
2019-10-09 13:22 ` Igor Mammedov [this message]
2019-10-10 13:04 ` [RFC 2/3] acpi: cpuhp: add typical usecases into spec Laszlo Ersek
2019-10-10 13:15 ` Laszlo Ersek
2019-10-10 14:13 ` Laszlo Ersek
2019-10-18 14:45 ` Igor Mammedov
2019-10-09 13:22 ` [RFC 3/3] acpi: cpuhp: add CPHP_GET_CPU_ID_CMD command Igor Mammedov
2019-10-10 14:56 ` Laszlo Ersek
2019-10-10 15:06 ` Michael S. Tsirkin
2019-10-10 17:23 ` Igor Mammedov
2019-10-10 17:53 ` Laszlo Ersek
2019-10-10 19:26 ` Eduardo Habkost
2019-10-11 8:07 ` Laszlo Ersek
2019-10-18 16:18 ` Igor Mammedov
2019-10-21 13:06 ` Laszlo Ersek
2019-10-22 12:39 ` Laszlo Ersek
2019-10-22 14:42 ` Igor Mammedov
2019-10-22 15:49 ` Laszlo Ersek
2019-10-23 14:59 ` Igor Mammedov
2019-10-24 15:07 ` Philippe Mathieu-Daudé
2019-10-10 9:56 ` [RFC 0/3] acpi: cphp: add CPHP_GET_CPU_ID_CMD command to cpu hotplug MMIO interface Michael S. Tsirkin
2019-10-10 13:39 ` Igor Mammedov
2019-10-10 13:59 ` Michael S. Tsirkin
2019-10-10 15:57 ` Igor Mammedov
2019-10-10 18:15 ` Michael S. Tsirkin
2019-10-11 7:41 ` Laszlo Ersek
2019-10-10 19:20 ` Eduardo Habkost
2019-10-11 8:01 ` Laszlo Ersek
2019-10-11 13:00 ` Michael S. Tsirkin
2019-10-11 16:13 ` Laszlo Ersek
2019-10-11 10:47 ` Igor Mammedov
2019-10-11 6:54 ` Laszlo Ersek
2019-10-10 14:16 ` Eduardo Habkost
2019-10-10 14:49 ` Michael S. Tsirkin
2019-10-10 17:09 ` Igor Mammedov
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