[PATCH 1/2] arm64: mm: apply __ro_after_init to memory_limit

From: Peng Fan <peng.fan@nxp.com>

This variable is only set during initialization, so mark with
__ro_after_init.

Signed-off-by: Peng Fan <peng.fan@nxp.com>
---
 arch/arm64/mm/init.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
index a8834434af99..db63cc885771 100644
--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c

@@ -172,7 +172,7 @@ int pfn_is_map_memory(unsigned long pfn)
 }
 EXPORT_SYMBOL(pfn_is_map_memory);
 
-static phys_addr_t memory_limit = PHYS_ADDR_MAX;
+static phys_addr_t memory_limit __ro_after_init = PHYS_ADDR_MAX;
 
 /*
  * Limit the memory size that was specified via FDT.

-- 
2.25.1


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From: Peng Fan <peng.fan@nxp.com>

There is a "mem=[x]" boot parameter, but when there is a whole reserved
by secure TEE, the continuous DRAM area is split with two memblocks.

For example, DRAM area [0x40000000, 0xffffffff], when TEE uses
[0x50000000, 0x51000000), the memblock will be split into
[0x40000000, 0x50000000) and [0x51000000, 0xffffffff].

If pass "mem=1024MB", the actually max addr will be 0x81000000.
However if need the max addr be 0x80000000, mem=1008MB should be used.

There also might be multiple other holes that no visible to Linux, when
we wanna to limit the max addr usable by Linux, using "max_addr=[X]" is
much easier than "mem=[X]"

Signed-off-by: Peng Fan <peng.fan@nxp.com>
---
 arch/arm64/mm/init.c | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
index db63cc885771..3364b5e7a7fe 100644
--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c

@@ -173,6 +173,7 @@ int pfn_is_map_memory(unsigned long pfn)
 EXPORT_SYMBOL(pfn_is_map_memory);
 
 static phys_addr_t memory_limit __ro_after_init = PHYS_ADDR_MAX;
+static phys_addr_t max_addr __ro_after_init = PHYS_ADDR_MAX;
 
 /*
  * Limit the memory size that was specified via FDT.

@@ -189,6 +190,18 @@ static int __init early_mem(char *p)
 }
 early_param("mem", early_mem);
 
+static int __init set_max_addr(char *p)
+{
+	if (!p)
+		return 1;
+
+	max_addr = memparse(p, &p) & PAGE_MASK;
+	pr_notice("Memory max addr set to 0x%llx\n", max_addr);
+
+	return 0;
+}
+early_param("max_addr", set_max_addr);
+
 void __init arm64_memblock_init(void)
 {
 	s64 linear_region_size = PAGE_END - _PAGE_OFFSET(vabits_actual);

@@ -253,6 +266,9 @@ void __init arm64_memblock_init(void)
 		memblock_add(__pa_symbol(_text), (u64)(_end - _text));
 	}
 
+	if (max_addr != PHYS_ADDR_MAX)
+		memblock_cap_memory_range(0, max_addr);
+
 	if (IS_ENABLED(CONFIG_BLK_DEV_INITRD) && phys_initrd_size) {
 		/*
 		 * Add back the memory we just removed if it results in the

@@ -427,4 +443,9 @@ void dump_mem_limit(void)
 	} else {
 		pr_emerg("Memory Limit: none\n");
 	}
+
+	if (max_addr != PHYS_ADDR_MAX)
+		pr_emerg("Max addr: 0x%llx\n", max_addr);
+	else
+		pr_emerg("Max addr: none\n");
 }

-- 
2.25.1


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http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

On Wed, 15 Dec 2021 at 07:56, Peng Fan (OSS) [off-list ref] wrote:

From: Peng Fan <peng.fan@nxp.com>

There is a "mem=[x]" boot parameter, but when there is a whole reserved
by secure TEE, the continuous DRAM area is split with two memblocks.

For example, DRAM area [0x40000000, 0xffffffff], when TEE uses
[0x50000000, 0x51000000), the memblock will be split into
[0x40000000, 0x50000000) and [0x51000000, 0xffffffff].

If pass "mem=1024MB", the actually max addr will be 0x81000000.
However if need the max addr be 0x80000000, mem=1008MB should be used.

There also might be multiple other holes that no visible to Linux, when
we wanna to limit the max addr usable by Linux, using "max_addr=[X]" is
much easier than "mem=[X]"

Signed-off-by: Peng Fan <peng.fan@nxp.com>

mem= is a hack already, please don't add another one. Limiting the
memory like this is far too tricky, given that the kernel itself and
the initrd could end up in memory that is excluded, and we have to go
and fix things up if that happens.

_______________________________________________
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linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

Subject: Re: [PATCH 2/2] arm64: mm: support bootparam max_addr

On Wed, 15 Dec 2021 at 07:56, Peng Fan (OSS) [off-list ref]
wrote:

quoted

From: Peng Fan <peng.fan@nxp.com>

There is a "mem=[x]" boot parameter, but when there is a whole
reserved by secure TEE, the continuous DRAM area is split with two

memblocks.

quoted

For example, DRAM area [0x40000000, 0xffffffff], when TEE uses
[0x50000000, 0x51000000), the memblock will be split into [0x40000000,
0x50000000) and [0x51000000, 0xffffffff].

If pass "mem=1024MB", the actually max addr will be 0x81000000.
However if need the max addr be 0x80000000, mem=1008MB should be

used.

quoted

There also might be multiple other holes that no visible to Linux,
when we wanna to limit the max addr usable by Linux, using
"max_addr=[X]" is much easier than "mem=[X]"

Signed-off-by: Peng Fan <peng.fan@nxp.com>

mem= is a hack already, please don't add another one. Limiting the memory
like this is far too tricky, given that the kernel itself and the initrd could end up
in memory that is excluded, and we have to go and fix things up if that
happens.

We wanna to use the reserved memory with request_mem_region, but with
commit 86588296acbfb1 ("fdt: Properly handle "no-map" field in the memory region ")

request_mem_region will fail, because the reserved memory are now as
kernel memory.

So we use "mem=X" to work around the issue, but "mem=X" is not user friendly
compared with "max_addr=" when there are multiple holes used by others.

Thanks,
Peng.

quoted

---
 arch/arm64/mm/init.c | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c index

db63cc885771..3364b5e7a7fe 100644

--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c

@@ -173,6 +173,7 @@ int pfn_is_map_memory(unsigned long pfn)

EXPORT_SYMBOL(pfn_is_map_memory);

 static phys_addr_t memory_limit __ro_after_init = PHYS_ADDR_MAX;
+static phys_addr_t max_addr __ro_after_init = PHYS_ADDR_MAX;

 /*
  * Limit the memory size that was specified via FDT.

@@ -189,6 +190,18 @@ static int __init early_mem(char *p)  }

early_param("mem", early_mem);

+static int __init set_max_addr(char *p) {
+       if (!p)
+               return 1;
+
+       max_addr = memparse(p, &p) & PAGE_MASK;
+       pr_notice("Memory max addr set to 0x%llx\n", max_addr);
+
+       return 0;
+}
+early_param("max_addr", set_max_addr);
+
 void __init arm64_memblock_init(void)  {
        s64 linear_region_size = PAGE_END -
_PAGE_OFFSET(vabits_actual); @@ -253,6 +266,9 @@ void __init

arm64_memblock_init(void)

quoted

                memblock_add(__pa_symbol(_text), (u64)(_end -

_text));

quoted

        }

+       if (max_addr != PHYS_ADDR_MAX)
+               memblock_cap_memory_range(0, max_addr);
+
        if (IS_ENABLED(CONFIG_BLK_DEV_INITRD) && phys_initrd_size)

{

quoted

                /*
                 * Add back the memory we just removed if it results
in the @@ -427,4 +443,9 @@ void dump_mem_limit(void)
        } else {
                pr_emerg("Memory Limit: none\n");
        }
+
+       if (max_addr != PHYS_ADDR_MAX)
+               pr_emerg("Max addr: 0x%llx\n", max_addr);
+       else
+               pr_emerg("Max addr: none\n");
 }
--
2.25.1


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.infradead.org%2Fmailman%2Flistinfo%2Flinux-arm-kernel&data=04%

7C0

quoted

1%7Cpeng.fan%40nxp.com%7C3ad0ef697ad64542556208d9bf9d1e1f%7C68
6ea1d3bc

quoted

2b4c6fa92cd99c5c301635%7C0%7C0%7C637751503805222488%7CUnknow
n%7CTWFpbG

quoted

Zsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6
Mn0%

quoted

3D%7C3000&sdata=iKVO4PUPnaRr%2B5gHcXxaaRxBt%2BK%2Fjytg8eQ
dCqgqh5o%

quoted

3D&reserved=0

_______________________________________________
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On Wed, Dec 15, 2021 at 07:59:45AM +0000, Peng Fan wrote:

quoted

Subject: Re: [PATCH 2/2] arm64: mm: support bootparam max_addr

On Wed, 15 Dec 2021 at 07:56, Peng Fan (OSS) [off-list ref]
wrote:

quoted

From: Peng Fan <peng.fan@nxp.com>

There is a "mem=[x]" boot parameter, but when there is a whole
reserved by secure TEE, the continuous DRAM area is split with two

memblocks.

quoted

For example, DRAM area [0x40000000, 0xffffffff], when TEE uses
[0x50000000, 0x51000000), the memblock will be split into [0x40000000,
0x50000000) and [0x51000000, 0xffffffff].

If pass "mem=1024MB", the actually max addr will be 0x81000000.
However if need the max addr be 0x80000000, mem=1008MB should be

used.

quoted

There also might be multiple other holes that no visible to Linux,
when we wanna to limit the max addr usable by Linux, using
"max_addr=[X]" is much easier than "mem=[X]"

Signed-off-by: Peng Fan <peng.fan@nxp.com>

mem= is a hack already, please don't add another one. Limiting the memory
like this is far too tricky, given that the kernel itself and the initrd could end up
in memory that is excluded, and we have to go and fix things up if that
happens.

We wanna to use the reserved memory with request_mem_region, but with
commit 86588296acbfb1 ("fdt: Properly handle "no-map" field in the memory region ")

request_mem_region will fail, because the reserved memory are now as
kernel memory.

 
request_mem_region() is for MMIO.  Why do you want to use it for RAM?

So we use "mem=X" to work around the issue, but "mem=X" is not user friendly
compared with "max_addr=" when there are multiple holes used by others.

Thanks,
Peng.

quoted

quoted

---
 arch/arm64/mm/init.c | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c index

db63cc885771..3364b5e7a7fe 100644

--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c

@@ -173,6 +173,7 @@ int pfn_is_map_memory(unsigned long pfn)

EXPORT_SYMBOL(pfn_is_map_memory);

 static phys_addr_t memory_limit __ro_after_init = PHYS_ADDR_MAX;
+static phys_addr_t max_addr __ro_after_init = PHYS_ADDR_MAX;

 /*
  * Limit the memory size that was specified via FDT.

@@ -189,6 +190,18 @@ static int __init early_mem(char *p)  }

early_param("mem", early_mem);

+static int __init set_max_addr(char *p) {
+       if (!p)
+               return 1;
+
+       max_addr = memparse(p, &p) & PAGE_MASK;
+       pr_notice("Memory max addr set to 0x%llx\n", max_addr);
+
+       return 0;
+}
+early_param("max_addr", set_max_addr);
+
 void __init arm64_memblock_init(void)  {
        s64 linear_region_size = PAGE_END -
_PAGE_OFFSET(vabits_actual); @@ -253,6 +266,9 @@ void __init

arm64_memblock_init(void)

quoted

                memblock_add(__pa_symbol(_text), (u64)(_end -

_text));

quoted

        }

+       if (max_addr != PHYS_ADDR_MAX)
+               memblock_cap_memory_range(0, max_addr);
+
        if (IS_ENABLED(CONFIG_BLK_DEV_INITRD) && phys_initrd_size)

{

quoted

                /*
                 * Add back the memory we just removed if it results
in the @@ -427,4 +443,9 @@ void dump_mem_limit(void)
        } else {
                pr_emerg("Memory Limit: none\n");
        }
+
+       if (max_addr != PHYS_ADDR_MAX)
+               pr_emerg("Max addr: 0x%llx\n", max_addr);
+       else
+               pr_emerg("Max addr: none\n");
 }
--
2.25.1


_______________________________________________
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.infradead.org%2Fmailman%2Flistinfo%2Flinux-arm-kernel&data=04%

7C0

quoted

1%7Cpeng.fan%40nxp.com%7C3ad0ef697ad64542556208d9bf9d1e1f%7C68
6ea1d3bc

quoted

2b4c6fa92cd99c5c301635%7C0%7C0%7C637751503805222488%7CUnknow
n%7CTWFpbG

quoted

Zsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6
Mn0%

quoted

3D%7C3000&sdata=iKVO4PUPnaRr%2B5gHcXxaaRxBt%2BK%2Fjytg8eQ
dCqgqh5o%

quoted

3D&reserved=0

-- 
Sincerely yours,
Mike.

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Subject: Re: [PATCH 2/2] arm64: mm: support bootparam max_addr

On Wed, Dec 15, 2021 at 07:59:45AM +0000, Peng Fan wrote:

quoted

quoted

Subject: Re: [PATCH 2/2] arm64: mm: support bootparam max_addr

On Wed, 15 Dec 2021 at 07:56, Peng Fan (OSS) [off-list ref]
wrote:

quoted

From: Peng Fan <peng.fan@nxp.com>

There is a "mem=[x]" boot parameter, but when there is a whole
reserved by secure TEE, the continuous DRAM area is split with two

memblocks.

quoted

For example, DRAM area [0x40000000, 0xffffffff], when TEE uses
[0x50000000, 0x51000000), the memblock will be split into
[0x40000000,
0x50000000) and [0x51000000, 0xffffffff].

If pass "mem=1024MB", the actually max addr will be 0x81000000.
However if need the max addr be 0x80000000, mem=1008MB should be

used.

quoted

There also might be multiple other holes that no visible to Linux,
when we wanna to limit the max addr usable by Linux, using
"max_addr=[X]" is much easier than "mem=[X]"

Signed-off-by: Peng Fan <peng.fan@nxp.com>

mem= is a hack already, please don't add another one. Limiting the
memory like this is far too tricky, given that the kernel itself and
the initrd could end up in memory that is excluded, and we have to
go and fix things up if that happens.

We wanna to use the reserved memory with request_mem_region, but with
commit 86588296acbfb1 ("fdt: Properly handle "no-map" field in the
memory region ")

request_mem_region will fail, because the reserved memory are now as
kernel memory.

request_mem_region() is for MMIO.  Why do you want to use it for RAM?

+ Jan, the jailhouse hypervisor owner.

There is an out of tree driver
https://github.com/siemens/jailhouse/blob/master/driver/main.c#L466

The hypervisor jailhouse is loaded after linux boot up, and the hypervisor
bin file needs to be loaded into DRAM that reserved in our device
tree with node with no map property.

And the hypervisor use virtual pci for communication between VMs,
The virtual pci use part of the reserved DRAM area as PCI MMIO space.

Maybe I should use /memreserve, but not node with no-map property.

Thanks,
Peng.

quoted

So we use "mem=X" to work around the issue, but "mem=X" is not user
friendly compared with "max_addr=" when there are multiple holes used by

others.

quoted

Thanks,
Peng.

quoted

quoted

---
 arch/arm64/mm/init.c | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c index

db63cc885771..3364b5e7a7fe 100644

--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c

@@ -173,6 +173,7 @@ int pfn_is_map_memory(unsigned long pfn)

EXPORT_SYMBOL(pfn_is_map_memory);

 static phys_addr_t memory_limit __ro_after_init = PHYS_ADDR_MAX;
+static phys_addr_t max_addr __ro_after_init = PHYS_ADDR_MAX;

 /*
  * Limit the memory size that was specified via FDT.

@@ -189,6 +190,18 @@ static int __init early_mem(char *p)  }

early_param("mem", early_mem);

+static int __init set_max_addr(char *p) {
+       if (!p)
+               return 1;
+
+       max_addr = memparse(p, &p) & PAGE_MASK;
+       pr_notice("Memory max addr set to 0x%llx\n", max_addr);
+
+       return 0;
+}
+early_param("max_addr", set_max_addr);
+
 void __init arm64_memblock_init(void)  {
        s64 linear_region_size = PAGE_END -
_PAGE_OFFSET(vabits_actual); @@ -253,6 +266,9 @@ void __init

arm64_memblock_init(void)

quoted

                memblock_add(__pa_symbol(_text), (u64)(_end -

_text));

quoted

        }

+       if (max_addr != PHYS_ADDR_MAX)
+               memblock_cap_memory_range(0, max_addr);
+
        if (IS_ENABLED(CONFIG_BLK_DEV_INITRD) &&

phys_initrd_size)

quoted

quoted

{

quoted

                /*
                 * Add back the memory we just removed if it
results in the @@ -427,4 +443,9 @@ void dump_mem_limit(void)
        } else {
                pr_emerg("Memory Limit: none\n");
        }
+
+       if (max_addr != PHYS_ADDR_MAX)
+               pr_emerg("Max addr: 0x%llx\n", max_addr);
+       else
+               pr_emerg("Max addr: none\n");
 }
--
2.25.1


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ists
.infradead.org%2Fmailman%2Flistinfo%2Flinux-arm-kernel&data=0

4

quoted

quoted

quoted

%

7C0

quoted

1%7Cpeng.fan%40nxp.com%7C3ad0ef697ad64542556208d9bf9d1e1f%7C68

quoted

quoted

6ea1d3bc

quoted

2b4c6fa92cd99c5c301635%7C0%7C0%7C637751503805222488%7CUnknow

quoted

quoted

n%7CTWFpbG

quoted

Zsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6

quoted

quoted

Mn0%

quoted

3D%7C3000&sdata=iKVO4PUPnaRr%2B5gHcXxaaRxBt%2BK%2Fjytg8eQ

quoted

quoted

dCqgqh5o%

quoted

3D&reserved=0

--
Sincerely yours,
Mike.

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

On Wed, Dec 15, 2021 at 09:30:36AM +0000, Peng Fan wrote:

quoted

Subject: Re: [PATCH 2/2] arm64: mm: support bootparam max_addr

On Wed, Dec 15, 2021 at 07:59:45AM +0000, Peng Fan wrote:

quoted

quoted

Subject: Re: [PATCH 2/2] arm64: mm: support bootparam max_addr

On Wed, 15 Dec 2021 at 07:56, Peng Fan (OSS) [off-list ref]
wrote:

quoted

From: Peng Fan <peng.fan@nxp.com>

There is a "mem=[x]" boot parameter, but when there is a whole
reserved by secure TEE, the continuous DRAM area is split with two

memblocks.

quoted

For example, DRAM area [0x40000000, 0xffffffff], when TEE uses
[0x50000000, 0x51000000), the memblock will be split into
[0x40000000,
0x50000000) and [0x51000000, 0xffffffff].

If pass "mem=1024MB", the actually max addr will be 0x81000000.
However if need the max addr be 0x80000000, mem=1008MB should be

used.

quoted

There also might be multiple other holes that no visible to Linux,
when we wanna to limit the max addr usable by Linux, using
"max_addr=[X]" is much easier than "mem=[X]"

Signed-off-by: Peng Fan <peng.fan@nxp.com>

mem= is a hack already, please don't add another one. Limiting the
memory like this is far too tricky, given that the kernel itself and
the initrd could end up in memory that is excluded, and we have to
go and fix things up if that happens.

We wanna to use the reserved memory with request_mem_region, but with
commit 86588296acbfb1 ("fdt: Properly handle "no-map" field in the
memory region ")

request_mem_region will fail, because the reserved memory are now as
kernel memory.

request_mem_region() is for MMIO.  Why do you want to use it for RAM?

+ Jan, the jailhouse hypervisor owner.

There is an out of tree driver
https://github.com/siemens/jailhouse/blob/master/driver/main.c#L466

The hypervisor jailhouse is loaded after linux boot up, and the hypervisor
bin file needs to be loaded into DRAM that reserved in our device
tree with node with no map property.

And the hypervisor use virtual pci for communication between VMs,
The virtual pci use part of the reserved DRAM area as PCI MMIO space.

Maybe I should use /memreserve, but not node with no-map property.

So, my understanding is that you need a chunk of memory that Linux does not
use and does not map into the kernel page tables.
In that case /memreserve + nomap in the device tree could be a better
solution than mem=X.
 

Thanks,
Peng.

quoted

quoted

So we use "mem=X" to work around the issue, but "mem=X" is not user
friendly compared with "max_addr=" when there are multiple holes used by

others.

quoted

Thanks,
Peng.

quoted

quoted

---
 arch/arm64/mm/init.c | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c index

db63cc885771..3364b5e7a7fe 100644

--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c

@@ -173,6 +173,7 @@ int pfn_is_map_memory(unsigned long pfn)

EXPORT_SYMBOL(pfn_is_map_memory);

 static phys_addr_t memory_limit __ro_after_init = PHYS_ADDR_MAX;
+static phys_addr_t max_addr __ro_after_init = PHYS_ADDR_MAX;

 /*
  * Limit the memory size that was specified via FDT.

@@ -189,6 +190,18 @@ static int __init early_mem(char *p)  }

early_param("mem", early_mem);

+static int __init set_max_addr(char *p) {
+       if (!p)
+               return 1;
+
+       max_addr = memparse(p, &p) & PAGE_MASK;
+       pr_notice("Memory max addr set to 0x%llx\n", max_addr);
+
+       return 0;
+}
+early_param("max_addr", set_max_addr);
+
 void __init arm64_memblock_init(void)  {
        s64 linear_region_size = PAGE_END -
_PAGE_OFFSET(vabits_actual); @@ -253,6 +266,9 @@ void __init

arm64_memblock_init(void)

quoted

                memblock_add(__pa_symbol(_text), (u64)(_end -

_text));

quoted

        }

+       if (max_addr != PHYS_ADDR_MAX)
+               memblock_cap_memory_range(0, max_addr);
+
        if (IS_ENABLED(CONFIG_BLK_DEV_INITRD) &&

phys_initrd_size)

quoted

quoted

{

quoted

                /*
                 * Add back the memory we just removed if it
results in the @@ -427,4 +443,9 @@ void dump_mem_limit(void)
        } else {
                pr_emerg("Memory Limit: none\n");
        }
+
+       if (max_addr != PHYS_ADDR_MAX)
+               pr_emerg("Max addr: 0x%llx\n", max_addr);
+       else
+               pr_emerg("Max addr: none\n");
 }
--
2.25.1


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4

quoted

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7C0

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1%7Cpeng.fan%40nxp.com%7C3ad0ef697ad64542556208d9bf9d1e1f%7C68

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2b4c6fa92cd99c5c301635%7C0%7C0%7C637751503805222488%7CUnknow

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dCqgqh5o%

quoted

3D&reserved=0

--
Sincerely yours,
Mike.

-- 
Sincerely yours,
Mike.

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Subject: Re: [PATCH 2/2] arm64: mm: support bootparam max_addr

On Wed, Dec 15, 2021 at 09:30:36AM +0000, Peng Fan wrote:

quoted

quoted

Subject: Re: [PATCH 2/2] arm64: mm: support bootparam max_addr

On Wed, Dec 15, 2021 at 07:59:45AM +0000, Peng Fan wrote:

quoted

quoted

Subject: Re: [PATCH 2/2] arm64: mm: support bootparam max_addr

On Wed, 15 Dec 2021 at 07:56, Peng Fan (OSS)
[off-list ref]
wrote:

quoted

From: Peng Fan <peng.fan@nxp.com>

There is a "mem=[x]" boot parameter, but when there is a whole
reserved by secure TEE, the continuous DRAM area is split with
two

memblocks.

quoted

For example, DRAM area [0x40000000, 0xffffffff], when TEE uses
[0x50000000, 0x51000000), the memblock will be split into
[0x40000000,
0x50000000) and [0x51000000, 0xffffffff].

If pass "mem=1024MB", the actually max addr will be 0x81000000.
However if need the max addr be 0x80000000, mem=1008MB

should

quoted

quoted

quoted

quoted

quoted

be

used.

quoted

There also might be multiple other holes that no visible to
Linux, when we wanna to limit the max addr usable by Linux,
using "max_addr=[X]" is much easier than "mem=[X]"

Signed-off-by: Peng Fan <peng.fan@nxp.com>

mem= is a hack already, please don't add another one. Limiting
the memory like this is far too tricky, given that the kernel
itself and the initrd could end up in memory that is excluded,
and we have to go and fix things up if that happens.

We wanna to use the reserved memory with request_mem_region, but
with commit 86588296acbfb1 ("fdt: Properly handle "no-map" field
in the memory region ")

request_mem_region will fail, because the reserved memory are now
as kernel memory.

request_mem_region() is for MMIO.  Why do you want to use it for

RAM?

quoted

+ Jan, the jailhouse hypervisor owner.

There is an out of tree driver
https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgith

ub.com%2Fsiemens%2Fjailhouse%2Fblob%2Fmaster%2Fdriver%2Fmain.c%23
L466&

quoted

amp;data=04%7C01%7Cpeng.fan%40nxp.com%7C0540c0c55ed24688f9f308d
9bfb0b7

quoted

7d%7C686ea1d3bc2b4c6fa92cd99c5c301635%7C0%7C0%7C6377515879788
01324%7CU

quoted

nknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI
6Ik1ha

quoted

WwiLCJXVCI6Mn0%3D%7C3000&sdata=owLVa3T4jnTPvohHwdEnP2%2F
uMiUJmYeTc

quoted

1TwM0i9iCE%3D&reserved=0

The hypervisor jailhouse is loaded after linux boot up, and the
hypervisor bin file needs to be loaded into DRAM that reserved in our
device tree with node with no map property.

And the hypervisor use virtual pci for communication between VMs, The
virtual pci use part of the reserved DRAM area as PCI MMIO space.

Maybe I should use /memreserve, but not node with no-map property.

So, my understanding is that you need a chunk of memory that Linux does not
use and does not map into the kernel page tables.
In that case /memreserve + nomap in the device tree could be a better
solution than mem=X.

nomap not work now since commit 
86588296acbfb1 ("fdt: Properly handle "no-map" field in the memory region ")

I need try /memreserve

BTW, do you think max_addr would be an option be added to memblock
common code mm/memblock.c?

Thanks,
Peng.

quoted

Thanks,
Peng.

quoted

quoted

So we use "mem=X" to work around the issue, but "mem=X" is not
user friendly compared with "max_addr=" when there are multiple
holes used by

others.

quoted

Thanks,
Peng.

quoted

quoted

---
 arch/arm64/mm/init.c | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c index

db63cc885771..3364b5e7a7fe 100644

--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c

@@ -173,6 +173,7 @@ int pfn_is_map_memory(unsigned long pfn)

EXPORT_SYMBOL(pfn_is_map_memory);

 static phys_addr_t memory_limit __ro_after_init =
PHYS_ADDR_MAX;
+static phys_addr_t max_addr __ro_after_init = PHYS_ADDR_MAX;

 /*
  * Limit the memory size that was specified via FDT.

@@ -189,6 +190,18 @@ static int __init early_mem(char *p)  }

early_param("mem", early_mem);

+static int __init set_max_addr(char *p) {
+       if (!p)
+               return 1;
+
+       max_addr = memparse(p, &p) & PAGE_MASK;
+       pr_notice("Memory max addr set to 0x%llx\n",
+ max_addr);
+
+       return 0;
+}
+early_param("max_addr", set_max_addr);
+
 void __init arm64_memblock_init(void)  {
        s64 linear_region_size = PAGE_END -
_PAGE_OFFSET(vabits_actual); @@ -253,6 +266,9 @@ void __init

arm64_memblock_init(void)

quoted

                memblock_add(__pa_symbol(_text), (u64)(_end

-

quoted

quoted

quoted

quoted

_text));

quoted

        }

+       if (max_addr != PHYS_ADDR_MAX)
+               memblock_cap_memory_range(0, max_addr);
+
        if (IS_ENABLED(CONFIG_BLK_DEV_INITRD) &&

phys_initrd_size)

quoted

quoted

{

quoted

                /*
                 * Add back the memory we just removed if it
results in the @@ -427,4 +443,9 @@ void dump_mem_limit(void)
        } else {
                pr_emerg("Memory Limit: none\n");
        }
+
+       if (max_addr != PHYS_ADDR_MAX)
+               pr_emerg("Max addr: 0x%llx\n", max_addr);
+       else
+               pr_emerg("Max addr: none\n");
 }
--
2.25.1


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ists
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4

quoted

quoted

quoted

%

7C0

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1%7Cpeng.fan%40nxp.com%7C3ad0ef697ad64542556208d9bf9d1e1f%7C68

quoted

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6ea1d3bc

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2b4c6fa92cd99c5c301635%7C0%7C0%7C637751503805222488%7CUnknow

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Zsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6

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3D%7C3000&sdata=iKVO4PUPnaRr%2B5gHcXxaaRxBt%2BK%2Fjytg8eQ

quoted

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quoted

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dCqgqh5o%

quoted

3D&reserved=0

--
Sincerely yours,
Mike.

--
Sincerely yours,
Mike.

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On Wed, Dec 15, 2021 at 12:05:36PM +0000, Peng Fan wrote:

quoted

Subject: Re: [PATCH 2/2] arm64: mm: support bootparam max_addr

quoted

quoted

quoted

quoted

quoted

If pass "mem=1024MB", the actually max addr will be
0x81000000.  However if need the max addr be 0x80000000,
mem=1008MB should be used.

BTW, do you think max_addr would be an option be added to memblock
common code mm/memblock.c?

You have a working solution with mem=1008MB, I don't see a need for
additional kernel parameter.

-- 
Sincerely yours,
Mike.

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On Wed, 15 Dec 2021 at 07:55, Peng Fan (OSS) [off-list ref] wrote:

From: Peng Fan <peng.fan@nxp.com>

This variable is only set during initialization, so mark with
__ro_after_init.

Signed-off-by: Peng Fan <peng.fan@nxp.com>

Acked-by: Ard Biesheuvel <ardb@kernel.org>

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On 15.12.21 07:45, Peng Fan (OSS) wrote:

Reviewed-by: David Hildenbrand <redacted>

-- 
Thanks,

David / dhildenb


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On Wed, 15 Dec 2021 14:45:58 +0800, Peng Fan (OSS) wrote:

From: Peng Fan <peng.fan@nxp.com>

This variable is only set during initialization, so mark with
__ro_after_init.

Applied to arm64 (for-next/core), thanks!

[1/2] arm64: mm: apply __ro_after_init to memory_limit
      https://git.kernel.org/arm64/c/bb425a759847

-- 
Catalin


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On 12/15/21 12:15 PM, Peng Fan (OSS) wrote:

Reviewed-by: Anshuman Khandual <redacted>

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