Re: [PATCH v3 5/6] fs/core/vmcore: Move sev_active() reference to x86 arch code
Hello Lianbo, lijiang 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 >> >> Adding Lianbo and Baoquan, who recently worked on this, for their review. >> > > This change looks good to me. > > Reviewed-by: Lianbo Jiang Thanks for your review! -- Thiago Jung Bauermann IBM Linux Technology Center
Re: [PATCH v3 5/6] fs/core/vmcore: Move sev_active() reference to x86 arch code
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
>
> Adding Lianbo and Baoquan, who recently worked on this, for their review.
>
This change looks good to me.
Reviewed-by: Lianbo Jiang
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 */
>>
>>
Re: [PATCH v3 5/6] fs/core/vmcore: Move sev_active() reference to x86 arch code
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
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 */
>
>
Re: [PATCH v3 5/6] fs/core/vmcore: Move sev_active() reference to x86 arch code
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
