[PATCH 0/4] update the xen config fragments

[PATCH 0/4] update the xen config fragments

[Lukas Bulwahn]

Dear xen maintainers,

here are three patches to update the xen config fragments to the currently
existing configs.

The fourth patch is just an addition to MAINTAINERS that I saw reasonable
after get_maintainers did not point to the XEN subsystem.

It applies cleanly on next-20220810.

Lukas

Lukas Bulwahn (4):
  xen: x86: set the config XEN_512GB after config change
  xen: remove XEN_SCRUB_PAGES in xen.config
  xen: move XEN_BALLOON_MEMORY_HOTPLUG to generic config
  MAINTAINERS: add xen config fragments to XEN HYPERVISOR sections

 MAINTAINERS                 | 2 ++
 arch/x86/configs/xen.config | 5 +----
 kernel/configs/xen.config   | 2 +-
 3 files changed, 4 insertions(+), 5 deletions(-)

-- 
2.17.1

[PATCH 1/4] xen: x86: set the config XEN_512GB after config change

[Lukas Bulwahn]

Commit c70727a5bc18 ("xen: allow more than 512 GB of RAM for 64 bit
pv-domains") from July 2015 replaces the config XEN_MAX_DOMAIN_MEMORY with
a new config XEN_512GB, but misses to adjust arch/x86/configs/xen.config.

Adjust this config fragment now.

Signed-off-by: Lukas Bulwahn <lukas.bulwahn@gmail.com>
---
 arch/x86/configs/xen.config | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/configs/xen.config b/arch/x86/configs/xen.config
index d9fc7139fd46..8a6c88f48e75 100644
--- a/arch/x86/configs/xen.config
+++ b/arch/x86/configs/xen.config
@@ -14,7 +14,7 @@ CONFIG_CPU_FREQ=y
 
 # x86 xen specific config options
 CONFIG_XEN_PVH=y
-CONFIG_XEN_MAX_DOMAIN_MEMORY=500
+CONFIG_XEN_512GB=y
 CONFIG_XEN_SAVE_RESTORE=y
 # CONFIG_XEN_DEBUG_FS is not set
 CONFIG_XEN_MCE_LOG=y
-- 
2.17.1

[PATCH 2/4] xen: remove XEN_SCRUB_PAGES in xen.config

[Lukas Bulwahn]

Commit 197ecb3802c0 ("xen/balloon: add runtime control for scrubbing
ballooned out pages") changed config XEN_SCRUB_PAGES to config
XEN_SCRUB_PAGES_DEFAULT. As xen.config sets 'XEN_BALLOON=y' and
XEN_SCRUB_PAGES_DEFAULT defaults to yes, there is no further need to set
this config in the xen.config file.

Remove setting XEN_SCRUB_PAGES in xen.config, which is without
effect since the commit above anyway.

Signed-off-by: Lukas Bulwahn <lukas.bulwahn@gmail.com>
---
 kernel/configs/xen.config | 1 -
 1 file changed, 1 deletion(-)

diff --git a/kernel/configs/xen.config b/kernel/configs/xen.config
index ff756221f112..436f806aa1ed 100644
--- a/kernel/configs/xen.config
+++ b/kernel/configs/xen.config
@@ -34,7 +34,6 @@ CONFIG_INPUT_XEN_KBDDEV_FRONTEND=m
 CONFIG_XEN_SCSI_FRONTEND=m
 # others
 CONFIG_XEN_BALLOON=y
-CONFIG_XEN_SCRUB_PAGES=y
 CONFIG_XEN_DEV_EVTCHN=m
 CONFIG_XEN_BLKDEV_FRONTEND=m
 CONFIG_XEN_NETDEV_FRONTEND=m
-- 
2.17.1

[PATCH 3/4] xen: move XEN_BALLOON_MEMORY_HOTPLUG to generic config

[Lukas Bulwahn]

While reviewing arch/x86/configs/xen.config, I noticed the following
note in this file:

  '# depends on MEMORY_HOTPLUG, arm64 doesn't enable this yet,
  '# move to generic config if it ever does.
  CONFIG_XEN_BALLOON_MEMORY_HOTPLUG=y

Commit 6c6685055a28 ("kconfig: add xenconfig defconfig helper") in June
2015 adds this note. Fortunately, commit 4ab215061554 ("arm64: Add memory
hotplug support") from December 2018 adds the memory hotplug in arm64, so
the precondition of this note above is now met.

Move setting the config XEN_BALLOON_MEMORY_HOTPLUG into the generic
xen.config now.

Signed-off-by: Lukas Bulwahn <lukas.bulwahn@gmail.com>
---
 arch/x86/configs/xen.config | 3 ---
 kernel/configs/xen.config   | 1 +
 2 files changed, 1 insertion(+), 3 deletions(-)

diff --git a/arch/x86/configs/xen.config b/arch/x86/configs/xen.config
index 8a6c88f48e75..024817bc4f0e 100644
--- a/arch/x86/configs/xen.config
+++ b/arch/x86/configs/xen.config
@@ -23,6 +23,3 @@ CONFIG_XEN_ACPI_PROCESSOR=m
 CONFIG_XEN_PCIDEV_BACKEND=m
 # x86 specific frontend drivers
 CONFIG_XEN_PCIDEV_FRONTEND=m
-# depends on MEMORY_HOTPLUG, arm64 doesn't enable this yet,
-# move to generic config if it ever does.
-CONFIG_XEN_BALLOON_MEMORY_HOTPLUG=y
diff --git a/kernel/configs/xen.config b/kernel/configs/xen.config
index 436f806aa1ed..ea84d5b3122d 100644
--- a/kernel/configs/xen.config
+++ b/kernel/configs/xen.config
@@ -34,6 +34,7 @@ CONFIG_INPUT_XEN_KBDDEV_FRONTEND=m
 CONFIG_XEN_SCSI_FRONTEND=m
 # others
 CONFIG_XEN_BALLOON=y
+CONFIG_XEN_BALLOON_MEMORY_HOTPLUG=y
 CONFIG_XEN_DEV_EVTCHN=m
 CONFIG_XEN_BLKDEV_FRONTEND=m
 CONFIG_XEN_NETDEV_FRONTEND=m
-- 
2.17.1

[PATCH 4/4] MAINTAINERS: add xen config fragments to XEN HYPERVISOR sections

[Lukas Bulwahn]

Make changes to the xen config fragments reach the XEN HYPERVISOR
maintainers and mailing list.

Signed-off-by: Lukas Bulwahn <lukas.bulwahn@gmail.com>
---
 MAINTAINERS | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/MAINTAINERS b/MAINTAINERS
index ee2098fc6f7c..6c2516b3da21 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -22217,12 +22217,14 @@ F:	drivers/*/xen-*front.c
 F:	drivers/xen/
 F:	include/uapi/xen/
 F:	include/xen/
+F:	kernel/configs/xen.config
 
 XEN HYPERVISOR X86
 M:	Juergen Gross <jgross@suse.com>
 R:	Boris Ostrovsky <boris.ostrovsky@oracle.com>
 L:	xen-devel@lists.xenproject.org (moderated for non-subscribers)
 S:	Supported
+F:	arch/x86/configs/xen.config
 F:	arch/x86/include/asm/pvclock-abi.h
 F:	arch/x86/include/asm/xen/
 F:	arch/x86/platform/pvh/
-- 
2.17.1

Re: [PATCH 1/4] xen: x86: set the config XEN_512GB after config change

[Jan Beulich]

On 10.08.2022 07:07, Lukas Bulwahn wrote:
> --- a/arch/x86/configs/xen.config
> +++ b/arch/x86/configs/xen.config
> @@ -14,7 +14,7 @@ CONFIG_CPU_FREQ=y
>  
>  # x86 xen specific config options
>  CONFIG_XEN_PVH=y
> -CONFIG_XEN_MAX_DOMAIN_MEMORY=500
> +CONFIG_XEN_512GB=y

Does this actually need setting here? The option's default is y, so
it ought to be turned on "automatically". Hence I think it's only
the stale line which wants deleting.

Jan

Re: [PATCH 3/4] xen: move XEN_BALLOON_MEMORY_HOTPLUG to generic config

[Oleksandr Tyshchenko]

On 10.08.22 08:07, Lukas Bulwahn wrote:

Hello Lukas, all

> While reviewing arch/x86/configs/xen.config, I noticed the following
> note in this file:
>
>    '# depends on MEMORY_HOTPLUG, arm64 doesn't enable this yet,
>    '# move to generic config if it ever does.
>    CONFIG_XEN_BALLOON_MEMORY_HOTPLUG=y
>
> Commit 6c6685055a28 ("kconfig: add xenconfig defconfig helper") in June
> 2015 adds this note. Fortunately, commit 4ab215061554 ("arm64: Add memory
> hotplug support") from December 2018 adds the memory hotplug in arm64, so
> the precondition of this note above is now met.
>
> Move setting the config XEN_BALLOON_MEMORY_HOTPLUG into the generic
> xen.config now.


I might have missed something but I have never heard of anyone using 
XEN_BALLOON_MEMORY_HOTPLUG on Arm.

Looking into the code, I am afraid, CONFIG_XEN_BALLOON_MEMORY_HOTPLUG 
won't be functional on Arm without reworking resource allocation logic 
in drivers/xen/ballon.c at least, since system "iomem_resource" cannot 
be used on Arm to allocate unused memory region(s), please see 
additional_memory_resource(). I might be wrong, but it feels to me that 
here we would need a similar logic like in 
drivers/xen/unpopulated-alloc.c which is functional on Arm since it uses 
specific Xen resource (on x86 it is just an iomem_resource, but on Arm 
it contains provided by the hypervisor extended regions).

I am not aware of anyone working on it, so I wouldn't enable that 
support on Arm by default until the code is updated.



>
> Signed-off-by: Lukas Bulwahn <lukas.bulwahn@gmail.com>
> ---
>   arch/x86/configs/xen.config | 3 ---
>   kernel/configs/xen.config   | 1 +
>   2 files changed, 1 insertion(+), 3 deletions(-)
>
> diff --git a/arch/x86/configs/xen.config b/arch/x86/configs/xen.config
> index 8a6c88f48e75..024817bc4f0e 100644
> --- a/arch/x86/configs/xen.config
> +++ b/arch/x86/configs/xen.config
> @@ -23,6 +23,3 @@ CONFIG_XEN_ACPI_PROCESSOR=m
>   CONFIG_XEN_PCIDEV_BACKEND=m
>   # x86 specific frontend drivers
>   CONFIG_XEN_PCIDEV_FRONTEND=m
> -# depends on MEMORY_HOTPLUG, arm64 doesn't enable this yet,
> -# move to generic config if it ever does.
> -CONFIG_XEN_BALLOON_MEMORY_HOTPLUG=y
> diff --git a/kernel/configs/xen.config b/kernel/configs/xen.config
> index 436f806aa1ed..ea84d5b3122d 100644
> --- a/kernel/configs/xen.config
> +++ b/kernel/configs/xen.config
> @@ -34,6 +34,7 @@ CONFIG_INPUT_XEN_KBDDEV_FRONTEND=m
>   CONFIG_XEN_SCSI_FRONTEND=m
>   # others
>   CONFIG_XEN_BALLOON=y
> +CONFIG_XEN_BALLOON_MEMORY_HOTPLUG=y
>   CONFIG_XEN_DEV_EVTCHN=m
>   CONFIG_XEN_BLKDEV_FRONTEND=m
>   CONFIG_XEN_NETDEV_FRONTEND=m

-- 
Regards,

Oleksandr Tyshchenko

Re: [PATCH 4/4] MAINTAINERS: add xen config fragments to XEN HYPERVISOR sections

[Juergen Gross]

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On 10.08.22 07:07, Lukas Bulwahn wrote:
> Make changes to the xen config fragments reach the XEN HYPERVISOR
> maintainers and mailing list.
> 
> Signed-off-by: Lukas Bulwahn <lukas.bulwahn@gmail.com>

Reviewed-by: Juergen Gross <jgross@suse.com>


Juergen

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Re: [PATCH 2/4] xen: remove XEN_SCRUB_PAGES in xen.config

[Juergen Gross]

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On 10.08.22 07:07, Lukas Bulwahn wrote:
> Commit 197ecb3802c0 ("xen/balloon: add runtime control for scrubbing
> ballooned out pages") changed config XEN_SCRUB_PAGES to config
> XEN_SCRUB_PAGES_DEFAULT. As xen.config sets 'XEN_BALLOON=y' and
> XEN_SCRUB_PAGES_DEFAULT defaults to yes, there is no further need to set
> this config in the xen.config file.
> 
> Remove setting XEN_SCRUB_PAGES in xen.config, which is without
> effect since the commit above anyway.
> 
> Signed-off-by: Lukas Bulwahn <lukas.bulwahn@gmail.com>

Reviewed-by: Juergen Gross <jgross@suse.com>


Juergen

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Re: [PATCH 2/4] xen: remove XEN_SCRUB_PAGES in xen.config

[Juergen Gross]

[-- Attachment #1.1.1: Type: text/plain, Size: 586 bytes --]

On 10.08.22 07:07, Lukas Bulwahn wrote:
> Commit 197ecb3802c0 ("xen/balloon: add runtime control for scrubbing
> ballooned out pages") changed config XEN_SCRUB_PAGES to config
> XEN_SCRUB_PAGES_DEFAULT. As xen.config sets 'XEN_BALLOON=y' and
> XEN_SCRUB_PAGES_DEFAULT defaults to yes, there is no further need to set
> this config in the xen.config file.
> 
> Remove setting XEN_SCRUB_PAGES in xen.config, which is without
> effect since the commit above anyway.
> 
> Signed-off-by: Lukas Bulwahn <lukas.bulwahn@gmail.com>

Pushed to xen/tip.git for-linus-6.0


Juergen

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Re: [PATCH 4/4] MAINTAINERS: add xen config fragments to XEN HYPERVISOR sections

[Juergen Gross]

[-- Attachment #1.1.1: Type: text/plain, Size: 257 bytes --]

On 10.08.22 07:07, Lukas Bulwahn wrote:
> Make changes to the xen config fragments reach the XEN HYPERVISOR
> maintainers and mailing list.
> 
> Signed-off-by: Lukas Bulwahn <lukas.bulwahn@gmail.com>

Pushed to xen/tip.git for-linus-6.0


Juergen

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Re: [PATCH 3/4] xen: move XEN_BALLOON_MEMORY_HOTPLUG to generic config

[Lukas Bulwahn]

On Wed, Aug 10, 2022 at 1:32 PM Oleksandr Tyshchenko
<Oleksandr_Tyshchenko@epam.com> wrote:
>
>
> On 10.08.22 08:07, Lukas Bulwahn wrote:
>
> Hello Lukas, all
>
> > While reviewing arch/x86/configs/xen.config, I noticed the following
> > note in this file:
> >
> >    '# depends on MEMORY_HOTPLUG, arm64 doesn't enable this yet,
> >    '# move to generic config if it ever does.
> >    CONFIG_XEN_BALLOON_MEMORY_HOTPLUG=y
> >
> > Commit 6c6685055a28 ("kconfig: add xenconfig defconfig helper") in June
> > 2015 adds this note. Fortunately, commit 4ab215061554 ("arm64: Add memory
> > hotplug support") from December 2018 adds the memory hotplug in arm64, so
> > the precondition of this note above is now met.
> >
> > Move setting the config XEN_BALLOON_MEMORY_HOTPLUG into the generic
> > xen.config now.
>
>
> I might have missed something but I have never heard of anyone using
> XEN_BALLOON_MEMORY_HOTPLUG on Arm.
>
> Looking into the code, I am afraid, CONFIG_XEN_BALLOON_MEMORY_HOTPLUG
> won't be functional on Arm without reworking resource allocation logic
> in drivers/xen/ballon.c at least, since system "iomem_resource" cannot
> be used on Arm to allocate unused memory region(s), please see
> additional_memory_resource(). I might be wrong, but it feels to me that
> here we would need a similar logic like in
> drivers/xen/unpopulated-alloc.c which is functional on Arm since it uses
> specific Xen resource (on x86 it is just an iomem_resource, but on Arm
> it contains provided by the hypervisor extended regions).
>
> I am not aware of anyone working on it, so I wouldn't enable that
> support on Arm by default until the code is updated.
>

Thanks for the in-depth investigation and explanation. For now, let us
drop this patch here and keep the configs as they are.

Lukas

Re: [PATCH 1/4] xen: x86: set the config XEN_512GB after config change

[Lukas Bulwahn]

On Wed, Aug 10, 2022 at 9:07 AM Jan Beulich <jbeulich@suse.com> wrote:
>
> On 10.08.2022 07:07, Lukas Bulwahn wrote:
> > --- a/arch/x86/configs/xen.config
> > +++ b/arch/x86/configs/xen.config
> > @@ -14,7 +14,7 @@ CONFIG_CPU_FREQ=y
> >
> >  # x86 xen specific config options
> >  CONFIG_XEN_PVH=y
> > -CONFIG_XEN_MAX_DOMAIN_MEMORY=500
> > +CONFIG_XEN_512GB=y
>
> Does this actually need setting here? The option's default is y, so
> it ought to be turned on "automatically". Hence I think it's only
> the stale line which wants deleting.
>

Jan, that makes sense. I will send a patch v2 to do so.

Lukas