[Xen-devel] [PATCH 2/2] xen: before ballooning hotplugged memory, set frames to invalid
Commit 25b884a83d487fd62c3de7ac1ab5549979188482 ("x86/xen: set
regions above the end of RAM as 1:1") introduced a regression.
To be able to add memory pages which were added via memory hotplug to
a pv domain, the pages must be "invalid" instead of "identity" in the
p2m list before they can be added.
Suggested-by: David Vrabel
Signed-off-by: Juergen Gross
---
drivers/xen/balloon.c | 13 +++--
1 file changed, 11 insertions(+), 2 deletions(-)
diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c
index 0b52d92..52e331f 100644
--- a/drivers/xen/balloon.c
+++ b/drivers/xen/balloon.c
@@ -221,15 +221,24 @@ static bool balloon_is_inflated(void)
static enum bp_state reserve_additional_memory(long credit)
{
- int nid, rc;
+ int nid, rc = 0;
u64 hotplug_start_paddr;
unsigned long balloon_hotplug = credit;
+ unsigned long pfn;
hotplug_start_paddr = PFN_PHYS(SECTION_ALIGN_UP(max_pfn));
balloon_hotplug = round_up(balloon_hotplug, PAGES_PER_SECTION);
nid = memory_add_physaddr_to_nid(hotplug_start_paddr);
- rc = add_memory(nid, hotplug_start_paddr, balloon_hotplug <<
PAGE_SHIFT);
+ for (pfn = PFN_DOWN(hotplug_start_paddr);
+!rc && pfn < PFN_DOWN(hotplug_start_paddr) + balloon_hotplug;
+pfn++)
+ if (!set_phys_to_machine(pfn, INVALID_P2M_ENTRY))
+ rc = 1;
+
+ if (!rc)
+ rc = add_memory(nid, hotplug_start_paddr,
+ balloon_hotplug << PAGE_SHIFT);
if (rc) {
pr_warn("Cannot add additional memory (%i)\n", rc);
--
2.1.4
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Re: [Xen-devel] [PATCH 2/2] xen: before ballooning hotplugged memory, set frames to invalid
On 19/03/15 14:31, Juergen Gross wrote:
> Commit 25b884a83d487fd62c3de7ac1ab5549979188482 ("x86/xen: set
> regions above the end of RAM as 1:1") introduced a regression.
>
> To be able to add memory pages which were added via memory hotplug to
> a pv domain, the pages must be "invalid" instead of "identity" in the
> p2m list before they can be added.
[...]
> --- a/drivers/xen/balloon.c
> +++ b/drivers/xen/balloon.c
> @@ -221,15 +221,24 @@ static bool balloon_is_inflated(void)
>
> static enum bp_state reserve_additional_memory(long credit)
> {
> - int nid, rc;
> + int nid, rc = 0;
> u64 hotplug_start_paddr;
> unsigned long balloon_hotplug = credit;
> + unsigned long pfn;
>
> hotplug_start_paddr = PFN_PHYS(SECTION_ALIGN_UP(max_pfn));
> balloon_hotplug = round_up(balloon_hotplug, PAGES_PER_SECTION);
> nid = memory_add_physaddr_to_nid(hotplug_start_paddr);
>
> - rc = add_memory(nid, hotplug_start_paddr, balloon_hotplug <<
> PAGE_SHIFT);
> + for (pfn = PFN_DOWN(hotplug_start_paddr);
> + !rc && pfn < PFN_DOWN(hotplug_start_paddr) + balloon_hotplug;
> + pfn++)
> + if (!set_phys_to_machine(pfn, INVALID_P2M_ENTRY))
> + rc = 1;
rc = -ENOMEM;
break;
> +
> + if (!rc)
> + rc = add_memory(nid, hotplug_start_paddr,
> + balloon_hotplug << PAGE_SHIFT);
Use else here.
> if (rc) {
> pr_warn("Cannot add additional memory (%i)\n", rc);
>
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Re: [Xen-devel] [PATCH 2/2] xen: before ballooning hotplugged memory, set frames to invalid
On Thu, Mar 19, 2015 at 03:31:02PM +0100, Juergen Gross wrote:
> Commit 25b884a83d487fd62c3de7ac1ab5549979188482 ("x86/xen: set
> regions above the end of RAM as 1:1") introduced a regression.
>
> To be able to add memory pages which were added via memory hotplug to
> a pv domain, the pages must be "invalid" instead of "identity" in the
> p2m list before they can be added.
>
> Suggested-by: David Vrabel
> Signed-off-by: Juergen Gross
> ---
> drivers/xen/balloon.c | 13 +++--
> 1 file changed, 11 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c
> index 0b52d92..52e331f 100644
> --- a/drivers/xen/balloon.c
> +++ b/drivers/xen/balloon.c
> @@ -221,15 +221,24 @@ static bool balloon_is_inflated(void)
>
> static enum bp_state reserve_additional_memory(long credit)
> {
> - int nid, rc;
> + int nid, rc = 0;
> u64 hotplug_start_paddr;
> unsigned long balloon_hotplug = credit;
> + unsigned long pfn;
>
> hotplug_start_paddr = PFN_PHYS(SECTION_ALIGN_UP(max_pfn));
> balloon_hotplug = round_up(balloon_hotplug, PAGES_PER_SECTION);
> nid = memory_add_physaddr_to_nid(hotplug_start_paddr);
>
> - rc = add_memory(nid, hotplug_start_paddr, balloon_hotplug <<
> PAGE_SHIFT);
> + for (pfn = PFN_DOWN(hotplug_start_paddr);
> + !rc && pfn < PFN_DOWN(hotplug_start_paddr) + balloon_hotplug;
> + pfn++)
> + if (!set_phys_to_machine(pfn, INVALID_P2M_ENTRY))
rc = set_phys_to_machine(pfn, INVALID_P2M_ENTRY)?
> + rc = 1;
I do not think that this stuff is needed for HVM or PVH guests.
> + if (!rc)
> + rc = add_memory(nid, hotplug_start_paddr,
> + balloon_hotplug << PAGE_SHIFT);
>
> if (rc) {
> pr_warn("Cannot add additional memory (%i)\n", rc);
It will be nice to know what part of infrastructure failed.
Could you create separate pr_warn() message for set_phys_to_machine()?
Daniel
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Re: [Xen-devel] [PATCH 2/2] xen: before ballooning hotplugged memory, set frames to invalid
On 03/19/2015 05:18 PM, David Vrabel wrote:
On 19/03/15 14:31, Juergen Gross wrote:
Commit 25b884a83d487fd62c3de7ac1ab5549979188482 ("x86/xen: set
regions above the end of RAM as 1:1") introduced a regression.
To be able to add memory pages which were added via memory hotplug to
a pv domain, the pages must be "invalid" instead of "identity" in the
p2m list before they can be added.
[...]
--- a/drivers/xen/balloon.c
+++ b/drivers/xen/balloon.c
@@ -221,15 +221,24 @@ static bool balloon_is_inflated(void)
static enum bp_state reserve_additional_memory(long credit)
{
- int nid, rc;
+ int nid, rc = 0;
u64 hotplug_start_paddr;
unsigned long balloon_hotplug = credit;
+ unsigned long pfn;
hotplug_start_paddr = PFN_PHYS(SECTION_ALIGN_UP(max_pfn));
balloon_hotplug = round_up(balloon_hotplug, PAGES_PER_SECTION);
nid = memory_add_physaddr_to_nid(hotplug_start_paddr);
- rc = add_memory(nid, hotplug_start_paddr, balloon_hotplug <<
PAGE_SHIFT);
+ for (pfn = PFN_DOWN(hotplug_start_paddr);
+!rc && pfn < PFN_DOWN(hotplug_start_paddr) + balloon_hotplug;
+pfn++)
+ if (!set_phys_to_machine(pfn, INVALID_P2M_ENTRY))
+ rc = 1;
rc = -ENOMEM;
I used the value 1 on purpose to be able to identify the case by the
value printed in the warning below.
break;
Why? !rc is already tested in the for() clause.
+
+ if (!rc)
+ rc = add_memory(nid, hotplug_start_paddr,
+ balloon_hotplug << PAGE_SHIFT);
Use else here.
Huh? I want the message to be printed if either set_phys_to_machine()
or add_memory() failed.
if (rc) {
pr_warn("Cannot add additional memory (%i)\n", rc);
Juergen
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Re: [Xen-devel] [PATCH 2/2] xen: before ballooning hotplugged memory, set frames to invalid
On 03/19/2015 05:21 PM, Daniel Kiper wrote:
On Thu, Mar 19, 2015 at 03:31:02PM +0100, Juergen Gross wrote:
Commit 25b884a83d487fd62c3de7ac1ab5549979188482 ("x86/xen: set
regions above the end of RAM as 1:1") introduced a regression.
To be able to add memory pages which were added via memory hotplug to
a pv domain, the pages must be "invalid" instead of "identity" in the
p2m list before they can be added.
Suggested-by: David Vrabel
Signed-off-by: Juergen Gross
---
drivers/xen/balloon.c | 13 +++--
1 file changed, 11 insertions(+), 2 deletions(-)
diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c
index 0b52d92..52e331f 100644
--- a/drivers/xen/balloon.c
+++ b/drivers/xen/balloon.c
@@ -221,15 +221,24 @@ static bool balloon_is_inflated(void)
static enum bp_state reserve_additional_memory(long credit)
{
- int nid, rc;
+ int nid, rc = 0;
u64 hotplug_start_paddr;
unsigned long balloon_hotplug = credit;
+ unsigned long pfn;
hotplug_start_paddr = PFN_PHYS(SECTION_ALIGN_UP(max_pfn));
balloon_hotplug = round_up(balloon_hotplug, PAGES_PER_SECTION);
nid = memory_add_physaddr_to_nid(hotplug_start_paddr);
- rc = add_memory(nid, hotplug_start_paddr, balloon_hotplug <<
PAGE_SHIFT);
+ for (pfn = PFN_DOWN(hotplug_start_paddr);
+!rc && pfn < PFN_DOWN(hotplug_start_paddr) + balloon_hotplug;
+pfn++)
+ if (!set_phys_to_machine(pfn, INVALID_P2M_ENTRY))
rc = set_phys_to_machine(pfn, INVALID_P2M_ENTRY)?
Not really. set_phys_to_machine returns false on failure...
+ rc = 1;
I do not think that this stuff is needed for HVM or PVH guests.
True.
+ if (!rc)
+ rc = add_memory(nid, hotplug_start_paddr,
+ balloon_hotplug << PAGE_SHIFT);
if (rc) {
pr_warn("Cannot add additional memory (%i)\n", rc);
It will be nice to know what part of infrastructure failed.
Could you create separate pr_warn() message for set_phys_to_machine()?
Value 1 for rc is the indicator for that case.
Juergen
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Re: [Xen-devel] [PATCH 2/2] xen: before ballooning hotplugged memory, set frames to invalid
On 19/03/15 17:19, Juergen Gross wrote:
> On 03/19/2015 05:18 PM, David Vrabel wrote:
>> On 19/03/15 14:31, Juergen Gross wrote:
>>> Commit 25b884a83d487fd62c3de7ac1ab5549979188482 ("x86/xen: set
>>> regions above the end of RAM as 1:1") introduced a regression.
>>>
>>> To be able to add memory pages which were added via memory hotplug to
>>> a pv domain, the pages must be "invalid" instead of "identity" in the
>>> p2m list before they can be added.
>> [...]
>>> --- a/drivers/xen/balloon.c
>>> +++ b/drivers/xen/balloon.c
>>> @@ -221,15 +221,24 @@ static bool balloon_is_inflated(void)
>>>
>>> static enum bp_state reserve_additional_memory(long credit)
>>> {
>>> -int nid, rc;
>>> +int nid, rc = 0;
>>> u64 hotplug_start_paddr;
>>> unsigned long balloon_hotplug = credit;
>>> +unsigned long pfn;
>>>
>>> hotplug_start_paddr = PFN_PHYS(SECTION_ALIGN_UP(max_pfn));
>>> balloon_hotplug = round_up(balloon_hotplug, PAGES_PER_SECTION);
>>> nid = memory_add_physaddr_to_nid(hotplug_start_paddr);
>>>
>>> -rc = add_memory(nid, hotplug_start_paddr, balloon_hotplug <<
>>> PAGE_SHIFT);
>>> +for (pfn = PFN_DOWN(hotplug_start_paddr);
>>> + !rc && pfn < PFN_DOWN(hotplug_start_paddr) + balloon_hotplug;
>>> + pfn++)
>>> +if (!set_phys_to_machine(pfn, INVALID_P2M_ENTRY))
>>> +rc = 1;
>>
>> rc = -ENOMEM;
>
> I used the value 1 on purpose to be able to identify the case by the
> value printed in the warning below.
Ok.
>
>> break;
>
> Why? !rc is already tested in the for() clause.
I prefer an explicit break.
>>> +
>>> +if (!rc)
>>> +rc = add_memory(nid, hotplug_start_paddr,
>>> +balloon_hotplug << PAGE_SHIFT);
>>
>> Use else here.
>
> Huh? I want the message to be printed if either set_phys_to_machine()
> or add_memory() failed.
Ok.
David
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Re: [Xen-devel] [PATCH 2/2] xen: before ballooning hotplugged memory, set frames to invalid
On Thu, Mar 19, 2015 at 06:22:06PM +0100, Juergen Gross wrote:
> On 03/19/2015 05:21 PM, Daniel Kiper wrote:
> >On Thu, Mar 19, 2015 at 03:31:02PM +0100, Juergen Gross wrote:
> >>Commit 25b884a83d487fd62c3de7ac1ab5549979188482 ("x86/xen: set
> >>regions above the end of RAM as 1:1") introduced a regression.
> >>
> >>To be able to add memory pages which were added via memory hotplug to
> >>a pv domain, the pages must be "invalid" instead of "identity" in the
> >>p2m list before they can be added.
> >>
> >>Suggested-by: David Vrabel
> >>Signed-off-by: Juergen Gross
> >>---
> >> drivers/xen/balloon.c | 13 +++--
> >> 1 file changed, 11 insertions(+), 2 deletions(-)
> >>
> >>diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c
> >>index 0b52d92..52e331f 100644
> >>--- a/drivers/xen/balloon.c
> >>+++ b/drivers/xen/balloon.c
> >>@@ -221,15 +221,24 @@ static bool balloon_is_inflated(void)
> >>
> >> static enum bp_state reserve_additional_memory(long credit)
> >> {
> >>- int nid, rc;
> >>+ int nid, rc = 0;
> >>u64 hotplug_start_paddr;
> >>unsigned long balloon_hotplug = credit;
> >>+ unsigned long pfn;
> >>
> >>hotplug_start_paddr = PFN_PHYS(SECTION_ALIGN_UP(max_pfn));
> >>balloon_hotplug = round_up(balloon_hotplug, PAGES_PER_SECTION);
> >>nid = memory_add_physaddr_to_nid(hotplug_start_paddr);
> >>
> >>- rc = add_memory(nid, hotplug_start_paddr, balloon_hotplug <<
> >>PAGE_SHIFT);
> >>+ for (pfn = PFN_DOWN(hotplug_start_paddr);
> >>+!rc && pfn < PFN_DOWN(hotplug_start_paddr) + balloon_hotplug;
> >>+pfn++)
> >>+ if (!set_phys_to_machine(pfn, INVALID_P2M_ENTRY))
> >
> >rc = set_phys_to_machine(pfn, INVALID_P2M_ENTRY)?
>
> Not really. set_phys_to_machine returns false on failure...
>
> >
> >>+ rc = 1;
> >
> >I do not think that this stuff is needed for HVM or PVH guests.
>
> True.
>
> >
> >>+ if (!rc)
> >>+ rc = add_memory(nid, hotplug_start_paddr,
> >>+ balloon_hotplug << PAGE_SHIFT);
> >>
> >>if (rc) {
> >>pr_warn("Cannot add additional memory (%i)\n", rc);
> >
> >It will be nice to know what part of infrastructure failed.
> >Could you create separate pr_warn() message for set_phys_to_machine()?
>
> Value 1 for rc is the indicator for that case.
Well... Personally I prefer explicit messages telling what happened than
something which requires digging in a code to understand a problem.
Additionally, I think that we should use negative numbers (as David
suggested) to signal an error. Most of kernel stuff work in that way.
Daniel
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