Re: [PATCH 3/3] fs/core/vmcore: Move sev_active() reference to x86 arch code
From: Halil Pasic <pasic@linux.ibm.com>
Date: 2019-07-12 13:09:27
Also in:
linux-fsdevel, linux-iommu, linux-s390, lkml
On Fri, 12 Jul 2019 02:36:31 -0300 Thiago Jung Bauermann [off-list ref] 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.
sev_active() might be just bad (too specific) name for a general concept. s390 code defines it drives the right behavior in kernel/dma/direct.c (which uses it).
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. Signed-off-by: Thiago Jung Bauermann <redacted> --- arch/x86/kernel/crash_dump_64.c | 5 +++++ fs/proc/vmcore.c | 8 ++++---- include/linux/crash_dump.h | 14 ++++++++++++++ include/linux/mem_encrypt.h | 1 - 4 files changed, 23 insertions(+), 5 deletions(-)
Does not seem to apply to today's or yesterdays master.
quoted hunk ↗ jump to hunk
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/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 f2e399fb626b..a3747fcae466 100644 --- a/include/linux/mem_encrypt.h +++ b/include/linux/mem_encrypt.h@@ -21,7 +21,6 @@ #else /* !CONFIG_ARCH_HAS_MEM_ENCRYPT */ -static inline bool sev_active(void) { return false; }
This is the implementation for the guys that don't
have ARCH_HAS_MEM_ENCRYPT.
Means sev_active() may not be used in such code after this
patch. What about
static inline bool force_dma_unencrypted(void)
{
return sev_active();
}
in kernel/dma/direct.c?
Regards,
Halil
static inline bool mem_encrypt_active(void) { return false; }
#endif /* CONFIG_ARCH_HAS_MEM_ENCRYPT */