[PATCH v2 0/2] x86: enable SWIOTLB if system has SRAT memory regions above MAX_DMA32_PFN

[PATCH v2 0/2] x86: enable SWIOTLB if system has SRAT memory regions above MAX_DMA32_PFN

[Igor Mammedov]

changes since v1:
  - reduce # of #ifdefs by introducing max_possible_pfn
    global variable
  - don't check 'acpi_no_memhotplug=1' for disabling
    SWIOTLB initialization, since existing 'no_iommu'
    kernel option could be used to the same effect.
  - split into 2 patches
      - 1st adds max_possible_pfn,
      - 2nd fixes bug enabling SWIOTLB when it's needed

when memory hotplug enabled system is booted with less
than 4GB of RAM and then later more RAM is hotplugged
32-bit devices stop functioning with following error:

 nommu_map_single: overflow 327b4f8c0+1522 of device mask ffffffff

the reason for this is that if x86_64 system were booted
with RAM less than 4GB, it doesn't enable SWIOTLB and
when memory is hotplugged beyond MAX_DMA32_PFN, devices
that expect 32-bit addresses can't handle 64-bit addresses.

Fix it by tracking max possible PFN when parsing
memory affinity structures from SRAT ACPI table and
enable SWIOTLB if there is hotpluggable memory
regions beyond MAX_DMA32_PFN.

It fixes KVM guests when they use emulated devices
(reproduces with ata_piix, e1000 and usb devices,
 RHBZ: 1275941, 1275977, 1271527)
It also fixes the HyperV, VMWare with emulated devices
which are affected by this issue as well.

ref to v1:
  https://lkml.org/lkml/2015/11/30/594

Igor Mammedov (2):
  x86: introduce max_possible_pfn
  x86_64: enable SWIOTLB if system has SRAT memory regions above
    MAX_DMA32_PFN

 arch/x86/kernel/pci-swiotlb.c | 2 +-
 arch/x86/kernel/setup.c       | 2 ++
 arch/x86/mm/srat.c            | 3 +++
 include/linux/bootmem.h       | 4 ++++
 mm/bootmem.c                  | 1 +
 mm/nobootmem.c                | 1 +
 6 files changed, 12 insertions(+), 1 deletion(-)

-- 
1.8.3.1

[PATCH v2 1/2] x86: introduce max_possible_pfn

[Igor Mammedov]

max_possible_pfn will be used for tracking max possible
PFN for memory that isn't present in E820 table and
could be hotplugged later.

By default max_possible_pfn is initialized with max_pfn,
but a follow up patch will update it with highest PFN of
hotpluggable memory ranges declared in ACPI SRAT table
if any present.

Signed-off-by: Igor Mammedov <imammedo@redhat.com>
---
 arch/x86/kernel/setup.c | 2 ++
 include/linux/bootmem.h | 4 ++++
 mm/bootmem.c            | 1 +
 mm/nobootmem.c          | 1 +
 4 files changed, 8 insertions(+)

diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index 29db25f..16a8465 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -1048,6 +1048,8 @@ void __init setup_arch(char **cmdline_p)
 	if (mtrr_trim_uncached_memory(max_pfn))
 		max_pfn = e820_end_of_ram_pfn();
 
+	max_possible_pfn = max_pfn;
+
 #ifdef CONFIG_X86_32
 	/* max_low_pfn get updated here */
 	find_low_pfn_range();
diff --git a/include/linux/bootmem.h b/include/linux/bootmem.h
index f589222..5b39aa5 100644
--- a/include/linux/bootmem.h
+++ b/include/linux/bootmem.h
@@ -19,6 +19,10 @@ extern unsigned long min_low_pfn;
  * highest page
  */
 extern unsigned long max_pfn;
+/*
+ * highest possible page
+ */
+extern unsigned long max_possible_pfn;
 
 #ifndef CONFIG_NO_BOOTMEM
 /*
diff --git a/mm/bootmem.c b/mm/bootmem.c
index 3b63807..221a04b 100644
--- a/mm/bootmem.c
+++ b/mm/bootmem.c
@@ -33,6 +33,7 @@ EXPORT_SYMBOL(contig_page_data);
 unsigned long max_low_pfn;
 unsigned long min_low_pfn;
 unsigned long max_pfn;
+unsigned long max_possible_pfn;
 
 bootmem_data_t bootmem_node_data[MAX_NUMNODES] __initdata;
 
diff --git a/mm/nobootmem.c b/mm/nobootmem.c
index e57cf24..08614c8 100644
--- a/mm/nobootmem.c
+++ b/mm/nobootmem.c
@@ -31,6 +31,7 @@ EXPORT_SYMBOL(contig_page_data);
 unsigned long max_low_pfn;
 unsigned long min_low_pfn;
 unsigned long max_pfn;
+unsigned long max_possible_pfn;
 
 static void * __init __alloc_memory_core_early(int nid, u64 size, u64 align,
 					u64 goal, u64 limit)
-- 
1.8.3.1

[PATCH v2 2/2] x86_64: enable SWIOTLB if system has SRAT memory regions above MAX_DMA32_PFN

[Igor Mammedov]

when memory hotplug enabled system is booted with less
than 4GB of RAM and then later more RAM is hotplugged
32-bit devices stop functioning with following error:

 nommu_map_single: overflow 327b4f8c0+1522 of device mask ffffffff

the reason for this is that if x86_64 system were booted
with RAM less than 4GB, it doesn't enable SWIOTLB and
when memory is hotplugged beyond MAX_DMA32_PFN, devices
that expect 32-bit addresses can't handle 64-bit addresses.

Fix it by tracking max possible PFN when parsing
memory affinity structures from SRAT ACPI table and
enable SWIOTLB if there is hotpluggable memory
regions beyond MAX_DMA32_PFN.

It fixes KVM guests when they use emulated devices
(reproduces with ata_piix, e1000 and usb devices,
 RHBZ: 1275941, 1275977, 1271527)
It also fixes the HyperV, VMWare with emulated devices
which are affected by this issue as well.

Signed-off-by: Igor Mammedov <imammedo@redhat.com>
---
 arch/x86/kernel/pci-swiotlb.c | 2 +-
 arch/x86/mm/srat.c            | 3 +++
 2 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kernel/pci-swiotlb.c b/arch/x86/kernel/pci-swiotlb.c
index adf0392..7c577a1 100644
--- a/arch/x86/kernel/pci-swiotlb.c
+++ b/arch/x86/kernel/pci-swiotlb.c
@@ -88,7 +88,7 @@ int __init pci_swiotlb_detect_4gb(void)
 {
 	/* don't initialize swiotlb if iommu=off (no_iommu=1) */
 #ifdef CONFIG_X86_64
-	if (!no_iommu && max_pfn > MAX_DMA32_PFN)
+	if (!no_iommu && max_possible_pfn > MAX_DMA32_PFN)
 		swiotlb = 1;
 #endif
 	return swiotlb;
diff --git a/arch/x86/mm/srat.c b/arch/x86/mm/srat.c
index c2aea63..a26bdbe 100644
--- a/arch/x86/mm/srat.c
+++ b/arch/x86/mm/srat.c
@@ -203,6 +203,9 @@ acpi_numa_memory_affinity_init(struct acpi_srat_mem_affinity *ma)
 		pr_warn("SRAT: Failed to mark hotplug range [mem %#010Lx-%#010Lx] in memblock\n",
 			(unsigned long long)start, (unsigned long long)end - 1);
 
+	if (max_possible_pfn < PFN_UP(end - 1))
+		max_possible_pfn = PFN_UP(end - 1);
+
 	return 0;
 out_err_bad_srat:
 	bad_srat();
-- 
1.8.3.1

Re: [PATCH v2 2/2] x86_64: enable SWIOTLB if system has SRAT memory regions above MAX_DMA32_PFN

[Ingo Molnar]

* Igor Mammedov <imammedo@redhat.com> wrote:

> when memory hotplug enabled system is booted with less
> than 4GB of RAM and then later more RAM is hotplugged
> 32-bit devices stop functioning with following error:
> 
>  nommu_map_single: overflow 327b4f8c0+1522 of device mask ffffffff
> 
> the reason for this is that if x86_64 system were booted
> with RAM less than 4GB, it doesn't enable SWIOTLB and
> when memory is hotplugged beyond MAX_DMA32_PFN, devices
> that expect 32-bit addresses can't handle 64-bit addresses.
> 
> Fix it by tracking max possible PFN when parsing
> memory affinity structures from SRAT ACPI table and
> enable SWIOTLB if there is hotpluggable memory
> regions beyond MAX_DMA32_PFN.
> 
> It fixes KVM guests when they use emulated devices
> (reproduces with ata_piix, e1000 and usb devices,
>  RHBZ: 1275941, 1275977, 1271527)
> It also fixes the HyperV, VMWare with emulated devices
> which are affected by this issue as well.
> 
> Signed-off-by: Igor Mammedov <imammedo@redhat.com>
> ---
>  arch/x86/kernel/pci-swiotlb.c | 2 +-
>  arch/x86/mm/srat.c            | 3 +++
>  2 files changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/x86/kernel/pci-swiotlb.c b/arch/x86/kernel/pci-swiotlb.c
> index adf0392..7c577a1 100644
> --- a/arch/x86/kernel/pci-swiotlb.c
> +++ b/arch/x86/kernel/pci-swiotlb.c
> @@ -88,7 +88,7 @@ int __init pci_swiotlb_detect_4gb(void)
>  {
>  	/* don't initialize swiotlb if iommu=off (no_iommu=1) */
>  #ifdef CONFIG_X86_64
> -	if (!no_iommu && max_pfn > MAX_DMA32_PFN)
> +	if (!no_iommu && max_possible_pfn > MAX_DMA32_PFN)
>  		swiotlb = 1;

Ok, this series looks a lot better!

>  #endif
>  	return swiotlb;
> diff --git a/arch/x86/mm/srat.c b/arch/x86/mm/srat.c
> index c2aea63..a26bdbe 100644
> --- a/arch/x86/mm/srat.c
> +++ b/arch/x86/mm/srat.c
> @@ -203,6 +203,9 @@ acpi_numa_memory_affinity_init(struct acpi_srat_mem_affinity *ma)
>  		pr_warn("SRAT: Failed to mark hotplug range [mem %#010Lx-%#010Lx] in memblock\n",
>  			(unsigned long long)start, (unsigned long long)end - 1);
>  
> +	if (max_possible_pfn < PFN_UP(end - 1))
> +		max_possible_pfn = PFN_UP(end - 1);

Small nit, why not write this as something like:

	max_possible_pfn = max(max_possible_pfn, PFN_UP(end - 1));

?

I'd also move this second hunk to the first patch, because logically it belongs 
there (or into a third patch).

Thanks,

	Ingo

Re: [PATCH v2 2/2] x86_64: enable SWIOTLB if system has SRAT memory regions above MAX_DMA32_PFN

[Igor Mammedov]

On Fri, 4 Dec 2015 12:49:49 +0100
Ingo Molnar <mingo@kernel.org> wrote:

> 
> * Igor Mammedov <imammedo@redhat.com> wrote:
> 
> > when memory hotplug enabled system is booted with less
> > than 4GB of RAM and then later more RAM is hotplugged
> > 32-bit devices stop functioning with following error:
> > 
> >  nommu_map_single: overflow 327b4f8c0+1522 of device mask ffffffff
> > 
> > the reason for this is that if x86_64 system were booted
> > with RAM less than 4GB, it doesn't enable SWIOTLB and
> > when memory is hotplugged beyond MAX_DMA32_PFN, devices
> > that expect 32-bit addresses can't handle 64-bit addresses.
> > 
> > Fix it by tracking max possible PFN when parsing
> > memory affinity structures from SRAT ACPI table and
> > enable SWIOTLB if there is hotpluggable memory
> > regions beyond MAX_DMA32_PFN.
> > 
> > It fixes KVM guests when they use emulated devices
> > (reproduces with ata_piix, e1000 and usb devices,
> >  RHBZ: 1275941, 1275977, 1271527)
> > It also fixes the HyperV, VMWare with emulated devices
> > which are affected by this issue as well.
> > 
> > Signed-off-by: Igor Mammedov <imammedo@redhat.com>
> > ---
> >  arch/x86/kernel/pci-swiotlb.c | 2 +-
> >  arch/x86/mm/srat.c            | 3 +++
> >  2 files changed, 4 insertions(+), 1 deletion(-)
> > 
> > diff --git a/arch/x86/kernel/pci-swiotlb.c b/arch/x86/kernel/pci-swiotlb.c
> > index adf0392..7c577a1 100644
> > --- a/arch/x86/kernel/pci-swiotlb.c
> > +++ b/arch/x86/kernel/pci-swiotlb.c
> > @@ -88,7 +88,7 @@ int __init pci_swiotlb_detect_4gb(void)
> >  {
> >  	/* don't initialize swiotlb if iommu=off (no_iommu=1) */
> >  #ifdef CONFIG_X86_64
> > -	if (!no_iommu && max_pfn > MAX_DMA32_PFN)
> > +	if (!no_iommu && max_possible_pfn > MAX_DMA32_PFN)
> >  		swiotlb = 1;
> 
> Ok, this series looks a lot better!
> 
> >  #endif
> >  	return swiotlb;
> > diff --git a/arch/x86/mm/srat.c b/arch/x86/mm/srat.c
> > index c2aea63..a26bdbe 100644
> > --- a/arch/x86/mm/srat.c
> > +++ b/arch/x86/mm/srat.c
> > @@ -203,6 +203,9 @@ acpi_numa_memory_affinity_init(struct acpi_srat_mem_affinity *ma)
> >  		pr_warn("SRAT: Failed to mark hotplug range [mem %#010Lx-%#010Lx] in memblock\n",
> >  			(unsigned long long)start, (unsigned long long)end - 1);
> >  
> > +	if (max_possible_pfn < PFN_UP(end - 1))
> > +		max_possible_pfn = PFN_UP(end - 1);
> 
> Small nit, why not write this as something like:
> 
> 	max_possible_pfn = max(max_possible_pfn, PFN_UP(end - 1));
> 
> ?
> 
> I'd also move this second hunk to the first patch, because logically it belongs 
> there (or into a third patch).
sure, I'll move it to the 1st patch

> 
> Thanks,
> 
> 	Ingo

Re: [PATCH v2 2/2] x86_64: enable SWIOTLB if system has SRAT memory regions above MAX_DMA32_PFN

[Igor Mammedov]

On Fri, 4 Dec 2015 12:49:49 +0100
Ingo Molnar <mingo@kernel.org> wrote:

> 
> * Igor Mammedov <imammedo@redhat.com> wrote:
> 
> > when memory hotplug enabled system is booted with less
> > than 4GB of RAM and then later more RAM is hotplugged
> > 32-bit devices stop functioning with following error:
> > 
> >  nommu_map_single: overflow 327b4f8c0+1522 of device mask ffffffff
> > 
> > the reason for this is that if x86_64 system were booted
> > with RAM less than 4GB, it doesn't enable SWIOTLB and
> > when memory is hotplugged beyond MAX_DMA32_PFN, devices
> > that expect 32-bit addresses can't handle 64-bit addresses.
> > 
> > Fix it by tracking max possible PFN when parsing
> > memory affinity structures from SRAT ACPI table and
> > enable SWIOTLB if there is hotpluggable memory
> > regions beyond MAX_DMA32_PFN.
> > 
> > It fixes KVM guests when they use emulated devices
> > (reproduces with ata_piix, e1000 and usb devices,
> >  RHBZ: 1275941, 1275977, 1271527)
> > It also fixes the HyperV, VMWare with emulated devices
> > which are affected by this issue as well.
> > 
> > Signed-off-by: Igor Mammedov <imammedo@redhat.com>
> > ---
> >  arch/x86/kernel/pci-swiotlb.c | 2 +-
> >  arch/x86/mm/srat.c            | 3 +++
> >  2 files changed, 4 insertions(+), 1 deletion(-)
> > 
> > diff --git a/arch/x86/kernel/pci-swiotlb.c b/arch/x86/kernel/pci-swiotlb.c
> > index adf0392..7c577a1 100644
> > --- a/arch/x86/kernel/pci-swiotlb.c
> > +++ b/arch/x86/kernel/pci-swiotlb.c
> > @@ -88,7 +88,7 @@ int __init pci_swiotlb_detect_4gb(void)
> >  {
> >  	/* don't initialize swiotlb if iommu=off (no_iommu=1) */
> >  #ifdef CONFIG_X86_64
> > -	if (!no_iommu && max_pfn > MAX_DMA32_PFN)
> > +	if (!no_iommu && max_possible_pfn > MAX_DMA32_PFN)
> >  		swiotlb = 1;
> 
> Ok, this series looks a lot better!
> 
> >  #endif
> >  	return swiotlb;
> > diff --git a/arch/x86/mm/srat.c b/arch/x86/mm/srat.c
> > index c2aea63..a26bdbe 100644
> > --- a/arch/x86/mm/srat.c
> > +++ b/arch/x86/mm/srat.c
> > @@ -203,6 +203,9 @@ acpi_numa_memory_affinity_init(struct acpi_srat_mem_affinity *ma)
> >  		pr_warn("SRAT: Failed to mark hotplug range [mem %#010Lx-%#010Lx] in memblock\n",
> >  			(unsigned long long)start, (unsigned long long)end - 1);
> >  
> > +	if (max_possible_pfn < PFN_UP(end - 1))
> > +		max_possible_pfn = PFN_UP(end - 1);
> 
> Small nit, why not write this as something like:
> 
> 	max_possible_pfn = max(max_possible_pfn, PFN_UP(end - 1));
That doesn't pass strict type check:

include/linux/kernel.h:730:17: warning: comparison of distinct pointer types lacks a cast [enabled by default]
  (void) (&_max1 == &_max2);  \
                 ^
arch/x86/mm/srat.c:206:21: note: in expansion of macro ‘max’
  max_possible_pfn = max(max_possible_pfn, PFN_UP(end - 1));

I can change max_possible_pfn to u64 to match PFN_UP(end - 1) type.

> 
> ?
> 
> I'd also move this second hunk to the first patch, because logically it belongs 
> there (or into a third patch).
> 
> Thanks,
> 
> 	Ingo

Re: [PATCH v2 2/2] x86_64: enable SWIOTLB if system has SRAT memory regions above MAX_DMA32_PFN

[Paolo Bonzini]

On 04/12/2015 13:33, Igor Mammedov wrote:
> That doesn't pass strict type check:
> 
> include/linux/kernel.h:730:17: warning: comparison of distinct pointer types lacks a cast [enabled by default]
>   (void) (&_max1 == &_max2);  \
>                  ^
> arch/x86/mm/srat.c:206:21: note: in expansion of macro ‘max’
>   max_possible_pfn = max(max_possible_pfn, PFN_UP(end - 1));
> 
> I can change max_possible_pfn to u64 to match PFN_UP(end - 1) type.

Sounds like a good idea anyway.

Paolo

Re: [PATCH v2 2/2] x86_64: enable SWIOTLB if system has SRAT memory regions above MAX_DMA32_PFN

[Ingo Molnar]

* Paolo Bonzini <pbonzini@redhat.com> wrote:

> On 04/12/2015 13:33, Igor Mammedov wrote:
> > That doesn't pass strict type check:
> > 
> > include/linux/kernel.h:730:17: warning: comparison of distinct pointer types lacks a cast [enabled by default]
> >   (void) (&_max1 == &_max2);  \
> >                  ^
> > arch/x86/mm/srat.c:206:21: note: in expansion of macro ‘max’
> >   max_possible_pfn = max(max_possible_pfn, PFN_UP(end - 1));
> > 
> > I can change max_possible_pfn to u64 to match PFN_UP(end - 1) type.
> 
> Sounds like a good idea anyway.

Yeah, agreed.

Thanks,

	Ingo