[v3,5/6] fs/core/vmcore: Move sev_active() reference to x86 arch code
diff mbox series

Message ID 20190718032858.28744-6-bauerman@linux.ibm.com
State Not Applicable
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  • Remove x86-specific code from generic headers
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Commit Message

Thiago Jung Bauermann July 18, 2019, 3:28 a.m. UTC
Secure Encrypted Virtualization is an x86-specific feature, so it shouldn't
appear in generic kernel code because it forces non-x86 architectures to
define the sev_active() function, which doesn't make a lot of sense.

To solve this problem, add an x86 elfcorehdr_read() function to override
the generic weak implementation. To do that, it's necessary to make
read_from_oldmem() public so that it can be used outside of vmcore.c.

Also, remove the export for sev_active() since it's only used in files that
won't be built as modules.

Signed-off-by: Thiago Jung Bauermann <bauerman@linux.ibm.com>
---
 arch/x86/kernel/crash_dump_64.c |  5 +++++
 arch/x86/mm/mem_encrypt.c       |  1 -
 fs/proc/vmcore.c                |  8 ++++----
 include/linux/crash_dump.h      | 14 ++++++++++++++
 include/linux/mem_encrypt.h     |  1 -
 5 files changed, 23 insertions(+), 6 deletions(-)

Comments

Christoph Hellwig July 18, 2019, 8:44 a.m. UTC | #1
On Thu, Jul 18, 2019 at 12:28:57AM -0300, Thiago Jung Bauermann wrote:
> Secure Encrypted Virtualization is an x86-specific feature, so it shouldn't
> appear in generic kernel code because it forces non-x86 architectures to
> define the sev_active() function, which doesn't make a lot of sense.
> 
> To solve this problem, add an x86 elfcorehdr_read() function to override
> the generic weak implementation. To do that, it's necessary to make
> read_from_oldmem() public so that it can be used outside of vmcore.c.
> 
> Also, remove the export for sev_active() since it's only used in files that
> won't be built as modules.

I have to say I find the __weak overrides of the vmcore files very
confusing and which we'd have a better scheme there.  But as this fits
into that scheme and allows to remove the AMD SME vs SEV knowledge from
the core I'm fine with it.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Lendacky, Thomas July 18, 2019, 5:47 p.m. UTC | #2
On 7/17/19 10:28 PM, Thiago Jung Bauermann wrote:
> Secure Encrypted Virtualization is an x86-specific feature, so it shouldn't
> appear in generic kernel code because it forces non-x86 architectures to
> define the sev_active() function, which doesn't make a lot of sense.
> 
> To solve this problem, add an x86 elfcorehdr_read() function to override
> the generic weak implementation. To do that, it's necessary to make
> read_from_oldmem() public so that it can be used outside of vmcore.c.
> 
> Also, remove the export for sev_active() since it's only used in files that
> won't be built as modules.
> 
> Signed-off-by: Thiago Jung Bauermann <bauerman@linux.ibm.com>

Adding Lianbo and Baoquan, who recently worked on this, for their review.

Thanks,
Tom

> ---
>  arch/x86/kernel/crash_dump_64.c |  5 +++++
>  arch/x86/mm/mem_encrypt.c       |  1 -
>  fs/proc/vmcore.c                |  8 ++++----
>  include/linux/crash_dump.h      | 14 ++++++++++++++
>  include/linux/mem_encrypt.h     |  1 -
>  5 files changed, 23 insertions(+), 6 deletions(-)
> 
> diff --git a/arch/x86/kernel/crash_dump_64.c b/arch/x86/kernel/crash_dump_64.c
> index 22369dd5de3b..045e82e8945b 100644
> --- a/arch/x86/kernel/crash_dump_64.c
> +++ b/arch/x86/kernel/crash_dump_64.c
> @@ -70,3 +70,8 @@ ssize_t copy_oldmem_page_encrypted(unsigned long pfn, char *buf, size_t csize,
>  {
>  	return __copy_oldmem_page(pfn, buf, csize, offset, userbuf, true);
>  }
> +
> +ssize_t elfcorehdr_read(char *buf, size_t count, u64 *ppos)
> +{
> +	return read_from_oldmem(buf, count, ppos, 0, sev_active());
> +}
> diff --git a/arch/x86/mm/mem_encrypt.c b/arch/x86/mm/mem_encrypt.c
> index 7139f2f43955..b1e823441093 100644
> --- a/arch/x86/mm/mem_encrypt.c
> +++ b/arch/x86/mm/mem_encrypt.c
> @@ -349,7 +349,6 @@ bool sev_active(void)
>  {
>  	return sme_me_mask && sev_enabled;
>  }
> -EXPORT_SYMBOL(sev_active);
>  
>  /* Override for DMA direct allocation check - ARCH_HAS_FORCE_DMA_UNENCRYPTED */
>  bool force_dma_unencrypted(struct device *dev)
> diff --git a/fs/proc/vmcore.c b/fs/proc/vmcore.c
> index 57957c91c6df..ca1f20bedd8c 100644
> --- a/fs/proc/vmcore.c
> +++ b/fs/proc/vmcore.c
> @@ -100,9 +100,9 @@ static int pfn_is_ram(unsigned long pfn)
>  }
>  
>  /* Reads a page from the oldmem device from given offset. */
> -static ssize_t read_from_oldmem(char *buf, size_t count,
> -				u64 *ppos, int userbuf,
> -				bool encrypted)
> +ssize_t read_from_oldmem(char *buf, size_t count,
> +			 u64 *ppos, int userbuf,
> +			 bool encrypted)
>  {
>  	unsigned long pfn, offset;
>  	size_t nr_bytes;
> @@ -166,7 +166,7 @@ void __weak elfcorehdr_free(unsigned long long addr)
>   */
>  ssize_t __weak elfcorehdr_read(char *buf, size_t count, u64 *ppos)
>  {
> -	return read_from_oldmem(buf, count, ppos, 0, sev_active());
> +	return read_from_oldmem(buf, count, ppos, 0, false);
>  }
>  
>  /*
> diff --git a/include/linux/crash_dump.h b/include/linux/crash_dump.h
> index f774c5eb9e3c..4664fc1871de 100644
> --- a/include/linux/crash_dump.h
> +++ b/include/linux/crash_dump.h
> @@ -115,4 +115,18 @@ static inline int vmcore_add_device_dump(struct vmcoredd_data *data)
>  	return -EOPNOTSUPP;
>  }
>  #endif /* CONFIG_PROC_VMCORE_DEVICE_DUMP */
> +
> +#ifdef CONFIG_PROC_VMCORE
> +ssize_t read_from_oldmem(char *buf, size_t count,
> +			 u64 *ppos, int userbuf,
> +			 bool encrypted);
> +#else
> +static inline ssize_t read_from_oldmem(char *buf, size_t count,
> +				       u64 *ppos, int userbuf,
> +				       bool encrypted)
> +{
> +	return -EOPNOTSUPP;
> +}
> +#endif /* CONFIG_PROC_VMCORE */
> +
>  #endif /* LINUX_CRASHDUMP_H */
> diff --git a/include/linux/mem_encrypt.h b/include/linux/mem_encrypt.h
> index 0c5b0ff9eb29..5c4a18a91f89 100644
> --- a/include/linux/mem_encrypt.h
> +++ b/include/linux/mem_encrypt.h
> @@ -19,7 +19,6 @@
>  #else	/* !CONFIG_ARCH_HAS_MEM_ENCRYPT */
>  
>  static inline bool mem_encrypt_active(void) { return false; }
> -static inline bool sev_active(void) { return false; }
>  
>  #endif	/* CONFIG_ARCH_HAS_MEM_ENCRYPT */
>  
>
lijiang July 19, 2019, 4:59 a.m. UTC | #3
在 2019年07月19日 01:47, Lendacky, Thomas 写道:
> On 7/17/19 10:28 PM, Thiago Jung Bauermann wrote:
>> Secure Encrypted Virtualization is an x86-specific feature, so it shouldn't
>> appear in generic kernel code because it forces non-x86 architectures to
>> define the sev_active() function, which doesn't make a lot of sense.
>>
>> To solve this problem, add an x86 elfcorehdr_read() function to override
>> the generic weak implementation. To do that, it's necessary to make
>> read_from_oldmem() public so that it can be used outside of vmcore.c.
>>
>> Also, remove the export for sev_active() since it's only used in files that
>> won't be built as modules.
>>
>> Signed-off-by: Thiago Jung Bauermann <bauerman@linux.ibm.com>
> 
> Adding Lianbo and Baoquan, who recently worked on this, for their review.
> 

This change looks good to me.

Reviewed-by: Lianbo Jiang <lijiang@redhat.com>

Thanks.
Lianbo

> Thanks,
> Tom
> 
>> ---
>>  arch/x86/kernel/crash_dump_64.c |  5 +++++
>>  arch/x86/mm/mem_encrypt.c       |  1 -
>>  fs/proc/vmcore.c                |  8 ++++----
>>  include/linux/crash_dump.h      | 14 ++++++++++++++
>>  include/linux/mem_encrypt.h     |  1 -
>>  5 files changed, 23 insertions(+), 6 deletions(-)
>>
>> diff --git a/arch/x86/kernel/crash_dump_64.c b/arch/x86/kernel/crash_dump_64.c
>> index 22369dd5de3b..045e82e8945b 100644
>> --- a/arch/x86/kernel/crash_dump_64.c
>> +++ b/arch/x86/kernel/crash_dump_64.c
>> @@ -70,3 +70,8 @@ ssize_t copy_oldmem_page_encrypted(unsigned long pfn, char *buf, size_t csize,
>>  {
>>  	return __copy_oldmem_page(pfn, buf, csize, offset, userbuf, true);
>>  }
>> +
>> +ssize_t elfcorehdr_read(char *buf, size_t count, u64 *ppos)
>> +{
>> +	return read_from_oldmem(buf, count, ppos, 0, sev_active());
>> +}
>> diff --git a/arch/x86/mm/mem_encrypt.c b/arch/x86/mm/mem_encrypt.c
>> index 7139f2f43955..b1e823441093 100644
>> --- a/arch/x86/mm/mem_encrypt.c
>> +++ b/arch/x86/mm/mem_encrypt.c
>> @@ -349,7 +349,6 @@ bool sev_active(void)
>>  {
>>  	return sme_me_mask && sev_enabled;
>>  }
>> -EXPORT_SYMBOL(sev_active);
>>  
>>  /* Override for DMA direct allocation check - ARCH_HAS_FORCE_DMA_UNENCRYPTED */
>>  bool force_dma_unencrypted(struct device *dev)
>> diff --git a/fs/proc/vmcore.c b/fs/proc/vmcore.c
>> index 57957c91c6df..ca1f20bedd8c 100644
>> --- a/fs/proc/vmcore.c
>> +++ b/fs/proc/vmcore.c
>> @@ -100,9 +100,9 @@ static int pfn_is_ram(unsigned long pfn)
>>  }
>>  
>>  /* Reads a page from the oldmem device from given offset. */
>> -static ssize_t read_from_oldmem(char *buf, size_t count,
>> -				u64 *ppos, int userbuf,
>> -				bool encrypted)
>> +ssize_t read_from_oldmem(char *buf, size_t count,
>> +			 u64 *ppos, int userbuf,
>> +			 bool encrypted)
>>  {
>>  	unsigned long pfn, offset;
>>  	size_t nr_bytes;
>> @@ -166,7 +166,7 @@ void __weak elfcorehdr_free(unsigned long long addr)
>>   */
>>  ssize_t __weak elfcorehdr_read(char *buf, size_t count, u64 *ppos)
>>  {
>> -	return read_from_oldmem(buf, count, ppos, 0, sev_active());
>> +	return read_from_oldmem(buf, count, ppos, 0, false);
>>  }
>>  
>>  /*
>> diff --git a/include/linux/crash_dump.h b/include/linux/crash_dump.h
>> index f774c5eb9e3c..4664fc1871de 100644
>> --- a/include/linux/crash_dump.h
>> +++ b/include/linux/crash_dump.h
>> @@ -115,4 +115,18 @@ static inline int vmcore_add_device_dump(struct vmcoredd_data *data)
>>  	return -EOPNOTSUPP;
>>  }
>>  #endif /* CONFIG_PROC_VMCORE_DEVICE_DUMP */
>> +
>> +#ifdef CONFIG_PROC_VMCORE
>> +ssize_t read_from_oldmem(char *buf, size_t count,
>> +			 u64 *ppos, int userbuf,
>> +			 bool encrypted);
>> +#else
>> +static inline ssize_t read_from_oldmem(char *buf, size_t count,
>> +				       u64 *ppos, int userbuf,
>> +				       bool encrypted)
>> +{
>> +	return -EOPNOTSUPP;
>> +}
>> +#endif /* CONFIG_PROC_VMCORE */
>> +
>>  #endif /* LINUX_CRASHDUMP_H */
>> diff --git a/include/linux/mem_encrypt.h b/include/linux/mem_encrypt.h
>> index 0c5b0ff9eb29..5c4a18a91f89 100644
>> --- a/include/linux/mem_encrypt.h
>> +++ b/include/linux/mem_encrypt.h
>> @@ -19,7 +19,6 @@
>>  #else	/* !CONFIG_ARCH_HAS_MEM_ENCRYPT */
>>  
>>  static inline bool mem_encrypt_active(void) { return false; }
>> -static inline bool sev_active(void) { return false; }
>>  
>>  #endif	/* CONFIG_ARCH_HAS_MEM_ENCRYPT */
>>  
>>
Thiago Jung Bauermann July 19, 2019, 3:47 p.m. UTC | #4
Hello Lianbo,

lijiang <lijiang@redhat.com> writes:

> 在 2019年07月19日 01:47, Lendacky, Thomas 写道:
>> On 7/17/19 10:28 PM, Thiago Jung Bauermann wrote:
>>> Secure Encrypted Virtualization is an x86-specific feature, so it shouldn't
>>> appear in generic kernel code because it forces non-x86 architectures to
>>> define the sev_active() function, which doesn't make a lot of sense.
>>>
>>> To solve this problem, add an x86 elfcorehdr_read() function to override
>>> the generic weak implementation. To do that, it's necessary to make
>>> read_from_oldmem() public so that it can be used outside of vmcore.c.
>>>
>>> Also, remove the export for sev_active() since it's only used in files that
>>> won't be built as modules.
>>>
>>> Signed-off-by: Thiago Jung Bauermann <bauerman@linux.ibm.com>
>> 
>> Adding Lianbo and Baoquan, who recently worked on this, for their review.
>> 
>
> This change looks good to me.
>
> Reviewed-by: Lianbo Jiang <lijiang@redhat.com>

Thanks for your review!

Patch
diff mbox series

diff --git a/arch/x86/kernel/crash_dump_64.c b/arch/x86/kernel/crash_dump_64.c
index 22369dd5de3b..045e82e8945b 100644
--- a/arch/x86/kernel/crash_dump_64.c
+++ b/arch/x86/kernel/crash_dump_64.c
@@ -70,3 +70,8 @@  ssize_t copy_oldmem_page_encrypted(unsigned long pfn, char *buf, size_t csize,
 {
 	return __copy_oldmem_page(pfn, buf, csize, offset, userbuf, true);
 }
+
+ssize_t elfcorehdr_read(char *buf, size_t count, u64 *ppos)
+{
+	return read_from_oldmem(buf, count, ppos, 0, sev_active());
+}
diff --git a/arch/x86/mm/mem_encrypt.c b/arch/x86/mm/mem_encrypt.c
index 7139f2f43955..b1e823441093 100644
--- a/arch/x86/mm/mem_encrypt.c
+++ b/arch/x86/mm/mem_encrypt.c
@@ -349,7 +349,6 @@  bool sev_active(void)
 {
 	return sme_me_mask && sev_enabled;
 }
-EXPORT_SYMBOL(sev_active);
 
 /* Override for DMA direct allocation check - ARCH_HAS_FORCE_DMA_UNENCRYPTED */
 bool force_dma_unencrypted(struct device *dev)
diff --git a/fs/proc/vmcore.c b/fs/proc/vmcore.c
index 57957c91c6df..ca1f20bedd8c 100644
--- a/fs/proc/vmcore.c
+++ b/fs/proc/vmcore.c
@@ -100,9 +100,9 @@  static int pfn_is_ram(unsigned long pfn)
 }
 
 /* Reads a page from the oldmem device from given offset. */
-static ssize_t read_from_oldmem(char *buf, size_t count,
-				u64 *ppos, int userbuf,
-				bool encrypted)
+ssize_t read_from_oldmem(char *buf, size_t count,
+			 u64 *ppos, int userbuf,
+			 bool encrypted)
 {
 	unsigned long pfn, offset;
 	size_t nr_bytes;
@@ -166,7 +166,7 @@  void __weak elfcorehdr_free(unsigned long long addr)
  */
 ssize_t __weak elfcorehdr_read(char *buf, size_t count, u64 *ppos)
 {
-	return read_from_oldmem(buf, count, ppos, 0, sev_active());
+	return read_from_oldmem(buf, count, ppos, 0, false);
 }
 
 /*
diff --git a/include/linux/crash_dump.h b/include/linux/crash_dump.h
index f774c5eb9e3c..4664fc1871de 100644
--- a/include/linux/crash_dump.h
+++ b/include/linux/crash_dump.h
@@ -115,4 +115,18 @@  static inline int vmcore_add_device_dump(struct vmcoredd_data *data)
 	return -EOPNOTSUPP;
 }
 #endif /* CONFIG_PROC_VMCORE_DEVICE_DUMP */
+
+#ifdef CONFIG_PROC_VMCORE
+ssize_t read_from_oldmem(char *buf, size_t count,
+			 u64 *ppos, int userbuf,
+			 bool encrypted);
+#else
+static inline ssize_t read_from_oldmem(char *buf, size_t count,
+				       u64 *ppos, int userbuf,
+				       bool encrypted)
+{
+	return -EOPNOTSUPP;
+}
+#endif /* CONFIG_PROC_VMCORE */
+
 #endif /* LINUX_CRASHDUMP_H */
diff --git a/include/linux/mem_encrypt.h b/include/linux/mem_encrypt.h
index 0c5b0ff9eb29..5c4a18a91f89 100644
--- a/include/linux/mem_encrypt.h
+++ b/include/linux/mem_encrypt.h
@@ -19,7 +19,6 @@ 
 #else	/* !CONFIG_ARCH_HAS_MEM_ENCRYPT */
 
 static inline bool mem_encrypt_active(void) { return false; }
-static inline bool sev_active(void) { return false; }
 
 #endif	/* CONFIG_ARCH_HAS_MEM_ENCRYPT */