| Message ID | 20190613163008.4060-1-jarkko.sakkinen@linux.intel.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [RFC] x86/sgx: Do not increase encl->refcount for VMAs | expand |
On Thu, Jun 13, 2019 at 07:30:07PM +0300, Jarkko Sakkinen wrote: > Since the device file stays open up until all VMAs have been closed > we do not need to increase encl->refcount for VMAs. sgx_open() will > increase it once and sgx_release() will decrease at a point where > the device file is not mapped. anymore. > > Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com> Cool if I merge this one? /Jarkko
On Mon, Jun 17, 2019 at 07:40:25PM +0300, Jarkko Sakkinen wrote: > On Thu, Jun 13, 2019 at 07:30:07PM +0300, Jarkko Sakkinen wrote: > > Since the device file stays open up until all VMAs have been closed > > we do not need to increase encl->refcount for VMAs. sgx_open() will > > increase it once and sgx_release() will decrease at a point where > > the device file is not mapped. anymore. > > > > Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com> > > Cool if I merge this one? LGTM
On Mon, 2019-06-17 at 09:52 -0700, Sean Christopherson wrote: > On Mon, Jun 17, 2019 at 07:40:25PM +0300, Jarkko Sakkinen wrote: > > On Thu, Jun 13, 2019 at 07:30:07PM +0300, Jarkko Sakkinen wrote: > > > Since the device file stays open up until all VMAs have been closed > > > we do not need to increase encl->refcount for VMAs. sgx_open() will > > > increase it once and sgx_release() will decrease at a point where > > > the device file is not mapped. anymore. > > > > > > Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com> > > > > Cool if I merge this one? > > LGTM Awesome, merged. Sent another similar change just now for the page adder. Can you check that so I can merge. I have a change in progress that will make the reclaimer also the reaper and remove the need for the refcount altogether. Try to get it possibly tonight out (i.e. daytime for you). /Jarkko
On Wed, Jun 19, 2019 at 03:46:38PM +0300, Jarkko Sakkinen wrote: > On Mon, 2019-06-17 at 09:52 -0700, Sean Christopherson wrote: > > On Mon, Jun 17, 2019 at 07:40:25PM +0300, Jarkko Sakkinen wrote: > > > On Thu, Jun 13, 2019 at 07:30:07PM +0300, Jarkko Sakkinen wrote: > > > > Since the device file stays open up until all VMAs have been closed > > > > we do not need to increase encl->refcount for VMAs. sgx_open() will > > > > increase it once and sgx_release() will decrease at a point where > > > > the device file is not mapped. anymore. > > > > > > > > Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com> > > > > > > Cool if I merge this one? > > > > LGTM > > Awesome, merged. > > Sent another similar change just now for the page adder. Can you > check that so I can merge. > > I have a change in progress that will make the reclaimer also the > reaper and remove the need for the refcount altogether. Try to > get it possibly tonight out (i.e. daytime for you). I'm about to disappear on vacation for two weeks, can you post whatever you have, even if it's half baked? I have a working patch to use mmu_notifier.release() instead of per-vma refcounting, I'll post an RFC today. It'd be nice to have both approaches posted so that folks can weigh in on the options for dropping .vm_close().
On Wed, Jun 19, 2019 at 08:34:19AM -0700, Sean Christopherson wrote: > > Sent another similar change just now for the page adder. Can you > > check that so I can merge. > > > > I have a change in progress that will make the reclaimer also the > > reaper and remove the need for the refcount altogether. Try to > > get it possibly tonight out (i.e. daytime for you). > > I'm about to disappear on vacation for two weeks, can you post whatever > you have, even if it's half baked? > > I have a working patch to use mmu_notifier.release() instead of per-vma > refcounting, I'll post an RFC today. It'd be nice to have both approaches > posted so that folks can weigh in on the options for dropping .vm_close(). I peeked your patch and it deals with the encl_mm->refcount. My changes deal with the encl->refcount (consolidating the driver to only use file's refcount). /Jarkko
diff --git a/arch/x86/kernel/cpu/sgx/driver/main.c b/arch/x86/kernel/cpu/sgx/driver/main.c index 87735ce8b5ba..0c831ee5e2de 100644 --- a/arch/x86/kernel/cpu/sgx/driver/main.c +++ b/arch/x86/kernel/cpu/sgx/driver/main.c @@ -68,8 +68,6 @@ static int sgx_mmap(struct file *file, struct vm_area_struct *vma) vma->vm_flags |= VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP | VM_IO; vma->vm_private_data = encl; - kref_get(&encl->refcount); - return 0; } diff --git a/arch/x86/kernel/cpu/sgx/encl.c b/arch/x86/kernel/cpu/sgx/encl.c index 6b190eccd02e..9566eb72d417 100644 --- a/arch/x86/kernel/cpu/sgx/encl.c +++ b/arch/x86/kernel/cpu/sgx/encl.c @@ -208,7 +208,6 @@ static void sgx_vma_open(struct vm_area_struct *vma) goto error; } - kref_get(&encl->refcount); return; error: @@ -230,8 +229,6 @@ static void sgx_vma_close(struct vm_area_struct *vma) /* Release kref for the VMA. */ kref_put(&encl_mm->refcount, sgx_encl_mm_release); } - - kref_put(&encl->refcount, sgx_encl_release); } static unsigned int sgx_vma_fault(struct vm_fault *vmf)
Since the device file stays open up until all VMAs have been closed we do not need to increase encl->refcount for VMAs. sgx_open() will increase it once and sgx_release() will decrease at a point where the device file is not mapped. anymore. Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com> --- Based on the commentary from Andy and Cedric. arch/x86/kernel/cpu/sgx/driver/main.c | 2 -- arch/x86/kernel/cpu/sgx/encl.c | 3 --- 2 files changed, 5 deletions(-)