Messages in this thread | | | Date | Fri, 12 Jul 2019 15:09:12 +0200 | From | Halil Pasic <> | Subject | Re: [PATCH 3/3] fs/core/vmcore: Move sev_active() reference to x86 arch code |
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On Fri, 12 Jul 2019 02:36:31 -0300 Thiago Jung Bauermann <bauerman@linux.ibm.com> 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 <bauerman@linux.ibm.com> > --- > 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.
> > 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 */
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