From: Oleksandr <olekstysh@gmail.com>
To: Jan Beulich <jbeulich@suse.com>
Cc: "Roger Pau Monné" <roger.pau@citrix.com>,
xen-devel@lists.xenproject.org,
"Oleksandr Tyshchenko" <oleksandr_tyshchenko@epam.com>,
"Stefano Stabellini" <sstabellini@kernel.org>,
"Julien Grall" <julien@xen.org>,
"Volodymyr Babchuk" <Volodymyr_Babchuk@epam.com>,
"Andrew Cooper" <andrew.cooper3@citrix.com>,
"George Dunlap" <george.dunlap@citrix.com>,
"Ian Jackson" <ian.jackson@eu.citrix.com>, "Wei Liu" <wl@xen.org>,
"Paul Durrant" <paul@xen.org>,
"Julien Grall" <julien.grall@arm.com>
Subject: Re: [PATCH V1 13/16] xen/ioreq: Make x86's invalidate qemu mapcache handling common
Date: Fri, 2 Oct 2020 12:55:45 +0300 [thread overview]
Message-ID: <0aa9a225-1231-fa98-f2a1-caf898a3ed86@gmail.com> (raw)
In-Reply-To: <47ecdde7-6575-bee8-7981-7b1a31715a0b@gmail.com>
Hi Jan
On 25.09.20 16:05, Oleksandr wrote:
>
> On 25.09.20 10:03, Jan Beulich wrote:
>
> Hi Jan.
>
>> On 24.09.2020 18:45, Oleksandr wrote:
>>> On 24.09.20 14:16, Jan Beulich wrote:
>>>
>>> Hi Jan
>>>
>>>> On 22.09.2020 21:32, Oleksandr wrote:
>>>>> On 16.09.20 11:50, Jan Beulich wrote:
>>>>>> On 10.09.2020 22:22, Oleksandr Tyshchenko wrote:
>>>>>>> --- a/xen/common/memory.c
>>>>>>> +++ b/xen/common/memory.c
>>>>>>> @@ -1651,6 +1651,11 @@ long do_memory_op(unsigned long cmd,
>>>>>>> XEN_GUEST_HANDLE_PARAM(void) arg)
>>>>>>> break;
>>>>>>> }
>>>>>>> +#ifdef CONFIG_IOREQ_SERVER
>>>>>>> + if ( op == XENMEM_decrease_reservation )
>>>>>>> + curr_d->qemu_mapcache_invalidate = true;
>>>>>>> +#endif
>>>>>> I don't see why you put this right into decrease_reservation(). This
>>>>>> isn't just to avoid the extra conditional, but first and foremost to
>>>>>> avoid bypassing the earlier return from the function (in the case of
>>>>>> preemption). In the context of this I wonder whether the ordering of
>>>>>> operations in hvm_hypercall() is actually correct.
>>>>> Good point, indeed we may return earlier in case of preemption, I
>>>>> missed
>>>>> that.
>>>>> Will move it to decrease_reservation(). But, we may return even
>>>>> earlier
>>>>> in case of error...
>>>>> Now I am wondering should we move it to the very beginning of command
>>>>> processing or not?
>>>> In _this_ series I'd strongly recommend you keep things working as
>>>> they are. If independently you think you've found a reason to
>>>> re-order certain operations, then feel free to send a patch with
>>>> suitable justification.
>>> Of course, I will try to retain current behavior.
>>>
>>>
>>>>>> I'm also unconvinced curr_d is the right domain in all cases here;
>>>>>> while this may be a pre-existing issue in principle, I'm afraid it
>>>>>> gets more pronounced by the logic getting moved to common code.
>>>>> Sorry I didn't get your concern here.
>>>> Well, you need to be concerned whose qemu_mapcache_invalidate flag
>>>> you set.
>>> May I ask, in what cases the *curr_d* is the right domain?
>> When a domain does a decrease-reservation on itself. I thought
>> that's obvious. But perhaps your question was rather meant a to
>> whether a->domain ever is _not_ the right one?
> No, my question was about *curr_d*. I saw your answer
> > I'm also unconvinced curr_d is the right domain in all cases here;
> and just wanted to clarify these cases. Sorry if I was unclear.
>
>
>>
>>> We need to make sure that domain is using IOREQ server(s) at least.
>>> Hopefully, we have a helper for this
>>> which is hvm_domain_has_ioreq_server(). Please clarify, anything else I
>>> should taking care of?
>> Nothing I can recall / think of right now, except that the change
>> may want to come under a different title and with a different
>> description.As indicated, I don't think this is correct for PVH
>> Dom0 issuing the request against a HVM DomU, and addressing this
>> will likely want this moved out of hvm_memory_op() anyway. Of
>> course an option is to split this into two patches - the proposed
>> bug fix (perhaps wanting backporting) and then the moving of the
>> field out of arch.hvm. If you feel uneasy about the bug fix part,
>> let me know and I (or maybe Roger) will see to put together a
>> patch.
>
> Thank you for the clarification.
>
> Yes, it would be really nice if you (or maybe Roger) could create a
> patch for the bug fix part.
Thank you for your patch [1].
If I got it correctly there won't be a suitable common place where to
set qemu_mapcache_invalidate flag anymore
as XENMEM_decrease_reservation is not a single place we need to make a
decision whether to set it
By principle of analogy, on Arm we probably want to do so in
guest_physmap_remove_page (or maybe better in p2m_remove_mapping).
Julien, what do you think?
I will modify current patch to not alter the common code.
[1] https://patchwork.kernel.org/patch/11803383/
--
Regards,
Oleksandr Tyshchenko
next prev parent reply other threads:[~2020-10-02 9:56 UTC|newest]
Thread overview: 111+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-10 20:21 [PATCH V1 00/16] IOREQ feature (+ virtio-mmio) on Arm Oleksandr Tyshchenko
2020-09-10 20:21 ` [PATCH V1 01/16] x86/ioreq: Prepare IOREQ feature for making it common Oleksandr Tyshchenko
2020-09-14 13:52 ` Jan Beulich
2020-09-21 12:22 ` Oleksandr
2020-09-21 12:31 ` Jan Beulich
2020-09-21 12:47 ` Oleksandr
2020-09-21 13:29 ` Jan Beulich
2020-09-21 14:43 ` Oleksandr
2020-09-21 15:28 ` Jan Beulich
2020-09-23 17:22 ` Julien Grall
2020-09-23 18:08 ` Oleksandr
2020-09-10 20:21 ` [PATCH V1 02/16] xen/ioreq: Make x86's IOREQ feature common Oleksandr Tyshchenko
2020-09-14 14:17 ` Jan Beulich
2020-09-21 19:02 ` Oleksandr
2020-09-22 6:33 ` Jan Beulich
2020-09-22 9:58 ` Oleksandr
2020-09-22 10:54 ` Jan Beulich
2020-09-22 15:05 ` Oleksandr
2020-09-22 15:52 ` Jan Beulich
2020-09-23 12:28 ` Oleksandr
2020-09-24 10:58 ` Jan Beulich
2020-09-24 15:38 ` Oleksandr
2020-09-24 15:51 ` Jan Beulich
2020-09-24 18:01 ` Julien Grall
2020-09-25 8:19 ` Paul Durrant
2020-09-30 13:39 ` Oleksandr
2020-09-30 17:47 ` Julien Grall
2020-10-01 6:59 ` Paul Durrant
2020-10-01 8:49 ` Jan Beulich
2020-10-01 8:50 ` Paul Durrant
2020-09-10 20:21 ` [PATCH V1 03/16] xen/ioreq: Make x86's hvm_ioreq_needs_completion() common Oleksandr Tyshchenko
2020-09-14 14:59 ` Jan Beulich
2020-09-22 16:16 ` Oleksandr
2020-09-23 17:27 ` Julien Grall
2020-09-10 20:21 ` [PATCH V1 04/16] xen/ioreq: Provide alias for the handle_mmio() Oleksandr Tyshchenko
2020-09-14 15:10 ` Jan Beulich
2020-09-22 16:20 ` Oleksandr
2020-09-23 17:28 ` Julien Grall
2020-09-23 18:17 ` Oleksandr
2020-09-10 20:21 ` [PATCH V1 05/16] xen/ioreq: Make x86's hvm_mmio_first(last)_byte() common Oleksandr Tyshchenko
2020-09-14 15:13 ` Jan Beulich
2020-09-22 16:24 ` Oleksandr
2020-09-10 20:22 ` [PATCH V1 06/16] xen/ioreq: Make x86's hvm_ioreq_(page/vcpu/server) structs common Oleksandr Tyshchenko
2020-09-14 15:16 ` Jan Beulich
2020-09-14 15:59 ` Julien Grall
2020-09-22 16:33 ` Oleksandr
2020-09-10 20:22 ` [PATCH V1 07/16] xen/dm: Make x86's DM feature common Oleksandr Tyshchenko
2020-09-14 15:56 ` Jan Beulich
2020-09-22 16:46 ` Oleksandr
2020-09-24 11:03 ` Jan Beulich
2020-09-24 12:47 ` Oleksandr
2020-09-23 17:35 ` Julien Grall
2020-09-23 18:28 ` Oleksandr
2020-09-10 20:22 ` [PATCH V1 08/16] xen/mm: Make x86's XENMEM_resource_ioreq_server handling common Oleksandr Tyshchenko
2020-09-10 20:22 ` [PATCH V1 09/16] arm/ioreq: Introduce arch specific bits for IOREQ/DM features Oleksandr Tyshchenko
2020-09-11 10:14 ` Oleksandr
2020-09-16 7:51 ` Jan Beulich
2020-09-22 17:12 ` Oleksandr
2020-09-23 18:03 ` Julien Grall
2020-09-23 20:16 ` Oleksandr
2020-09-24 11:08 ` Jan Beulich
2020-09-24 16:02 ` Oleksandr
2020-09-24 18:02 ` Oleksandr
2020-09-25 6:51 ` Jan Beulich
2020-09-25 9:47 ` Oleksandr
2020-09-26 13:12 ` Julien Grall
2020-09-26 13:18 ` Oleksandr
2020-09-24 16:51 ` Julien Grall
2020-09-24 17:25 ` Julien Grall
2020-09-24 18:22 ` Oleksandr
2020-09-26 13:21 ` Julien Grall
2020-09-26 14:57 ` Oleksandr
2020-09-10 20:22 ` [PATCH V1 10/16] xen/mm: Handle properly reference in set_foreign_p2m_entry() on Arm Oleksandr Tyshchenko
2020-09-16 7:17 ` Jan Beulich
2020-09-16 8:50 ` Julien Grall
2020-09-16 8:52 ` Jan Beulich
2020-09-16 8:55 ` Julien Grall
2020-09-22 17:30 ` Oleksandr
2020-09-16 8:08 ` Jan Beulich
2020-09-10 20:22 ` [PATCH V1 11/16] xen/ioreq: Introduce hvm_domain_has_ioreq_server() Oleksandr Tyshchenko
2020-09-16 8:04 ` Jan Beulich
2020-09-16 8:13 ` Paul Durrant
2020-09-16 8:39 ` Julien Grall
2020-09-16 8:43 ` Paul Durrant
2020-09-22 18:39 ` Oleksandr
2020-09-22 18:23 ` Oleksandr
2020-09-10 20:22 ` [PATCH V1 12/16] xen/dm: Introduce xendevicemodel_set_irq_level DM op Oleksandr Tyshchenko
2020-09-26 13:50 ` Julien Grall
2020-09-26 14:21 ` Oleksandr
2020-09-10 20:22 ` [PATCH V1 13/16] xen/ioreq: Make x86's invalidate qemu mapcache handling common Oleksandr Tyshchenko
2020-09-16 8:50 ` Jan Beulich
2020-09-22 19:32 ` Oleksandr
2020-09-24 11:16 ` Jan Beulich
2020-09-24 16:45 ` Oleksandr
2020-09-25 7:03 ` Jan Beulich
2020-09-25 13:05 ` Oleksandr
2020-10-02 9:55 ` Oleksandr [this message]
2020-10-07 10:38 ` Julien Grall
2020-10-07 12:01 ` Oleksandr
2020-09-10 20:22 ` [PATCH V1 14/16] xen/ioreq: Use guest_cmpxchg64() instead of cmpxchg() Oleksandr Tyshchenko
2020-09-16 9:04 ` Jan Beulich
2020-09-16 9:07 ` Julien Grall
2020-09-16 9:09 ` Paul Durrant
2020-09-16 9:12 ` Julien Grall
2020-09-22 20:05 ` Oleksandr
2020-09-23 18:12 ` Julien Grall
2020-09-23 20:29 ` Oleksandr
2020-09-16 9:07 ` Paul Durrant
2020-09-23 18:05 ` Julien Grall
2020-09-10 20:22 ` [PATCH V1 15/16] libxl: Introduce basic virtio-mmio support on Arm Oleksandr Tyshchenko
2020-09-10 20:22 ` [PATCH V1 16/16] [RFC] libxl: Add support for virtio-disk configuration Oleksandr Tyshchenko
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