[v4,31/33] powerc/mm: try VMA lock-based page fault handling first
Commit Message
From: Laurent Dufour <ldufour@linux.ibm.com>
Attempt VMA lock-based page fault handling first, and fall back to the
existing mmap_lock-based handling if that fails.
Copied from "x86/mm: try VMA lock-based page fault handling first"
Signed-off-by: Laurent Dufour <ldufour@linux.ibm.com>
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
---
arch/powerpc/mm/fault.c | 41 ++++++++++++++++++++++++++
arch/powerpc/platforms/powernv/Kconfig | 1 +
arch/powerpc/platforms/pseries/Kconfig | 1 +
3 files changed, 43 insertions(+)
Comments
On Mon, Feb 27, 2023 at 9:37 AM Suren Baghdasaryan <surenb@google.com> wrote:
>
> From: Laurent Dufour <ldufour@linux.ibm.com>
>
> Attempt VMA lock-based page fault handling first, and fall back to the
> existing mmap_lock-based handling if that fails.
> Copied from "x86/mm: try VMA lock-based page fault handling first"
Hi Andrew,
Laurent posted a fix for this patch at
https://lore.kernel.org/all/20230306154244.17560-1-ldufour@linux.ibm.com/.
Could you please squash the fix into this patch?
Thanks,
Suren.
>
> Signed-off-by: Laurent Dufour <ldufour@linux.ibm.com>
> Signed-off-by: Suren Baghdasaryan <surenb@google.com>
> ---
> arch/powerpc/mm/fault.c | 41 ++++++++++++++++++++++++++
> arch/powerpc/platforms/powernv/Kconfig | 1 +
> arch/powerpc/platforms/pseries/Kconfig | 1 +
> 3 files changed, 43 insertions(+)
>
> diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c
> index 2bef19cc1b98..c7ae86b04b8a 100644
> --- a/arch/powerpc/mm/fault.c
> +++ b/arch/powerpc/mm/fault.c
> @@ -469,6 +469,44 @@ static int ___do_page_fault(struct pt_regs *regs, unsigned long address,
> if (is_exec)
> flags |= FAULT_FLAG_INSTRUCTION;
>
> +#ifdef CONFIG_PER_VMA_LOCK
> + if (!(flags & FAULT_FLAG_USER))
> + goto lock_mmap;
> +
> + vma = lock_vma_under_rcu(mm, address);
> + if (!vma)
> + goto lock_mmap;
> +
> + if (unlikely(access_pkey_error(is_write, is_exec,
> + (error_code & DSISR_KEYFAULT), vma))) {
> + int rc = bad_access_pkey(regs, address, vma);
> +
> + vma_end_read(vma);
> + return rc;
> + }
> +
> + if (unlikely(access_error(is_write, is_exec, vma))) {
> + int rc = bad_access(regs, address);
> +
> + vma_end_read(vma);
> + return rc;
> + }
> +
> + fault = handle_mm_fault(vma, address, flags | FAULT_FLAG_VMA_LOCK, regs);
> + vma_end_read(vma);
> +
> + if (!(fault & VM_FAULT_RETRY)) {
> + count_vm_vma_lock_event(VMA_LOCK_SUCCESS);
> + goto done;
> + }
> + count_vm_vma_lock_event(VMA_LOCK_RETRY);
> +
> + if (fault_signal_pending(fault, regs))
> + return user_mode(regs) ? 0 : SIGBUS;
> +
> +lock_mmap:
> +#endif /* CONFIG_PER_VMA_LOCK */
> +
> /* When running in the kernel we expect faults to occur only to
> * addresses in user space. All other faults represent errors in the
> * kernel and should generate an OOPS. Unfortunately, in the case of an
> @@ -545,6 +583,9 @@ static int ___do_page_fault(struct pt_regs *regs, unsigned long address,
>
> mmap_read_unlock(current->mm);
>
> +#ifdef CONFIG_PER_VMA_LOCK
> +done:
> +#endif
> if (unlikely(fault & VM_FAULT_ERROR))
> return mm_fault_error(regs, address, fault);
>
> diff --git a/arch/powerpc/platforms/powernv/Kconfig b/arch/powerpc/platforms/powernv/Kconfig
> index ae248a161b43..70a46acc70d6 100644
> --- a/arch/powerpc/platforms/powernv/Kconfig
> +++ b/arch/powerpc/platforms/powernv/Kconfig
> @@ -16,6 +16,7 @@ config PPC_POWERNV
> select PPC_DOORBELL
> select MMU_NOTIFIER
> select FORCE_SMP
> + select ARCH_SUPPORTS_PER_VMA_LOCK
> default y
>
> config OPAL_PRD
> diff --git a/arch/powerpc/platforms/pseries/Kconfig b/arch/powerpc/platforms/pseries/Kconfig
> index b481c5c8bae1..9c205fe0e619 100644
> --- a/arch/powerpc/platforms/pseries/Kconfig
> +++ b/arch/powerpc/platforms/pseries/Kconfig
> @@ -21,6 +21,7 @@ config PPC_PSERIES
> select HOTPLUG_CPU
> select FORCE_SMP
> select SWIOTLB
> + select ARCH_SUPPORTS_PER_VMA_LOCK
> default y
>
> config PARAVIRT
> --
> 2.39.2.722.g9855ee24e9-goog
>
@@ -469,6 +469,44 @@ static int ___do_page_fault(struct pt_regs *regs, unsigned long address,
if (is_exec)
flags |= FAULT_FLAG_INSTRUCTION;
+#ifdef CONFIG_PER_VMA_LOCK
+ if (!(flags & FAULT_FLAG_USER))
+ goto lock_mmap;
+
+ vma = lock_vma_under_rcu(mm, address);
+ if (!vma)
+ goto lock_mmap;
+
+ if (unlikely(access_pkey_error(is_write, is_exec,
+ (error_code & DSISR_KEYFAULT), vma))) {
+ int rc = bad_access_pkey(regs, address, vma);
+
+ vma_end_read(vma);
+ return rc;
+ }
+
+ if (unlikely(access_error(is_write, is_exec, vma))) {
+ int rc = bad_access(regs, address);
+
+ vma_end_read(vma);
+ return rc;
+ }
+
+ fault = handle_mm_fault(vma, address, flags | FAULT_FLAG_VMA_LOCK, regs);
+ vma_end_read(vma);
+
+ if (!(fault & VM_FAULT_RETRY)) {
+ count_vm_vma_lock_event(VMA_LOCK_SUCCESS);
+ goto done;
+ }
+ count_vm_vma_lock_event(VMA_LOCK_RETRY);
+
+ if (fault_signal_pending(fault, regs))
+ return user_mode(regs) ? 0 : SIGBUS;
+
+lock_mmap:
+#endif /* CONFIG_PER_VMA_LOCK */
+
/* When running in the kernel we expect faults to occur only to
* addresses in user space. All other faults represent errors in the
* kernel and should generate an OOPS. Unfortunately, in the case of an
@@ -545,6 +583,9 @@ static int ___do_page_fault(struct pt_regs *regs, unsigned long address,
mmap_read_unlock(current->mm);
+#ifdef CONFIG_PER_VMA_LOCK
+done:
+#endif
if (unlikely(fault & VM_FAULT_ERROR))
return mm_fault_error(regs, address, fault);
@@ -16,6 +16,7 @@ config PPC_POWERNV
select PPC_DOORBELL
select MMU_NOTIFIER
select FORCE_SMP
+ select ARCH_SUPPORTS_PER_VMA_LOCK
default y
config OPAL_PRD
@@ -21,6 +21,7 @@ config PPC_PSERIES
select HOTPLUG_CPU
select FORCE_SMP
select SWIOTLB
+ select ARCH_SUPPORTS_PER_VMA_LOCK
default y
config PARAVIRT