On Fri, Oct 07, 2022 at 08:23:03AM -0700, Ira Weiny wrote:
> On Thu, Sep 29, 2022 at 09:06:46AM -0700, Kristen Carlson Accardi wrote:
> > It is not necessary to disable page faults or preemption when
> > using kmap calls, so replace kmap_atomic() and kunmap_atomic()
> > calls with more the more appropriate kmap_local_page() and
> > kunmap_local() calls.
> >
> > Signed-off-by: Kristen Carlson Accardi <kristen@xxxxxxxxxxxxxxx>
>
> Minor comment below.
>
> > ---
> > arch/x86/kernel/cpu/sgx/encl.c | 12 ++++++------
> > arch/x86/kernel/cpu/sgx/ioctl.c | 4 ++--
> > arch/x86/kernel/cpu/sgx/main.c | 8 ++++----
> > 3 files changed, 12 insertions(+), 12 deletions(-)
> >
> > diff --git a/arch/x86/kernel/cpu/sgx/encl.c b/arch/x86/kernel/cpu/sgx/encl.c
> > index f40d64206ded..63dd92bd3288 100644
> > --- a/arch/x86/kernel/cpu/sgx/encl.c
> > +++ b/arch/x86/kernel/cpu/sgx/encl.c
> > @@ -160,8 +160,8 @@ static int __sgx_encl_eldu(struct sgx_encl_page *encl_page,
> > return ret;
> >
> > pginfo.addr = encl_page->desc & PAGE_MASK;
> > - pginfo.contents = (unsigned long)kmap_atomic(b.contents);
> > - pcmd_page = kmap_atomic(b.pcmd);
> > + pginfo.contents = (unsigned long)kmap_local_page(b.contents);
> > + pcmd_page = kmap_local_page(b.pcmd);
> > pginfo.metadata = (unsigned long)pcmd_page + b.pcmd_offset;
> >
> > if (secs_page)
> > @@ -187,8 +187,8 @@ static int __sgx_encl_eldu(struct sgx_encl_page *encl_page,
> > */
> > pcmd_page_empty = !memchr_inv(pcmd_page, 0, PAGE_SIZE);
> >
> > - kunmap_atomic(pcmd_page);
> > - kunmap_atomic((void *)(unsigned long)pginfo.contents);
> > + kunmap_local(pcmd_page);
> > + kunmap_local((void *)(unsigned long)pginfo.contents);
> >
> > get_page(b.pcmd);
> > sgx_encl_put_backing(&b);
> > @@ -197,10 +197,10 @@ static int __sgx_encl_eldu(struct sgx_encl_page *encl_page,
> >
> > if (pcmd_page_empty && !reclaimer_writing_to_pcmd(encl, pcmd_first_page)) {
> > sgx_encl_truncate_backing_page(encl, PFN_DOWN(page_pcmd_off));
> > - pcmd_page = kmap_atomic(b.pcmd);
> > + pcmd_page = kmap_local_page(b.pcmd);
> > if (memchr_inv(pcmd_page, 0, PAGE_SIZE))
> > pr_warn("PCMD page not empty after truncate.\n");
> > - kunmap_atomic(pcmd_page);
> > + kunmap_local(pcmd_page);
> > }
> >
> > put_page(b.pcmd);
> > diff --git a/arch/x86/kernel/cpu/sgx/ioctl.c b/arch/x86/kernel/cpu/sgx/ioctl.c
> > index ebe79d60619f..f2f918b8b9b1 100644
> > --- a/arch/x86/kernel/cpu/sgx/ioctl.c
> > +++ b/arch/x86/kernel/cpu/sgx/ioctl.c
> > @@ -221,11 +221,11 @@ static int __sgx_encl_add_page(struct sgx_encl *encl,
> > pginfo.secs = (unsigned long)sgx_get_epc_virt_addr(encl->secs.epc_page);
> > pginfo.addr = encl_page->desc & PAGE_MASK;
> > pginfo.metadata = (unsigned long)secinfo;
> > - pginfo.contents = (unsigned long)kmap_atomic(src_page);
> > + pginfo.contents = (unsigned long)kmap_local_page(src_page);
> >
> > ret = __eadd(&pginfo, sgx_get_epc_virt_addr(epc_page));
> >
> > - kunmap_atomic((void *)pginfo.contents);
> > + kunmap_local((void *)pginfo.contents);
> > put_page(src_page);
> >
> > return ret ? -EIO : 0;
> > diff --git a/arch/x86/kernel/cpu/sgx/main.c b/arch/x86/kernel/cpu/sgx/main.c
> > index 515e2a5f25bb..4efda5e8cadf 100644
> > --- a/arch/x86/kernel/cpu/sgx/main.c
> > +++ b/arch/x86/kernel/cpu/sgx/main.c
> > @@ -159,17 +159,17 @@ static int __sgx_encl_ewb(struct sgx_epc_page *epc_page, void *va_slot,
> > pginfo.addr = 0;
> > pginfo.secs = 0;
> >
> > - pginfo.contents = (unsigned long)kmap_atomic(backing->contents);
> > - pginfo.metadata = (unsigned long)kmap_atomic(backing->pcmd) +
> > + pginfo.contents = (unsigned long)kmap_local_page(backing->contents);
> > + pginfo.metadata = (unsigned long)kmap_local_page(backing->pcmd) +
> > backing->pcmd_offset;
> >
> > ret = __ewb(&pginfo, sgx_get_epc_virt_addr(epc_page), va_slot);
> > set_page_dirty(backing->pcmd);
> > set_page_dirty(backing->contents);
> >
> > - kunmap_atomic((void *)(unsigned long)(pginfo.metadata -
> > + kunmap_local((void *)(unsigned long)(pginfo.metadata -
> > backing->pcmd_offset));
>
> For kunmap_local() one can use any address in the page. So this can be:
>
> kunmap_local((void *)(unsigned long)(pginfo.metadata));
>
>
> Regardless:
>
> Reviewed-by: Ira Weiny <ira.weiny@xxxxxxxxx>
There's no data to show that this change would be useful to do.
Thus, as said earlier, the commit message is missing "why".
Definitive NAK with the current offering.
BR, Jarkko
