diff mbox series

[RFC,v3,2/4] x86/sgx: Implement support for MADV_WILLNEED

Message ID 20221107220212.257422-3-haitao.huang@linux.intel.com (mailing list archive)
State New, archived
Headers show
Series x86/sgx: implement support for MADV_WILLNEED | expand

Commit Message

Haitao Huang Nov. 7, 2022, 10:02 p.m. UTC 
Support madvise(..., MADV_WILLNEED) by adding EPC pages with EAUG in
the newly added fops->fadvise() callback implementation, sgx_fadvise().

Change the return type and values of the sgx_encl_eaug_page function
so that more specific error codes are returned for different treatment
by the page fault handler and the fadvise callback.
On any error, sgx_fadvise() will discontinue further operations
and return as normal. The page fault handler allows a PF retried
by returning VM_FAULT_NOPAGE in handling -EBUSY returned from
sgx_encl_eaug_page.

Signed-off-by: Haitao Huang <haitao.huang@linux.intel.com>
---
 arch/x86/kernel/cpu/sgx/driver.c | 76 ++++++++++++++++++++++++++++++++
 arch/x86/kernel/cpu/sgx/encl.c   | 46 ++++++++++++-------
 arch/x86/kernel/cpu/sgx/encl.h   |  4 +-
 3 files changed, 108 insertions(+), 18 deletions(-)

Comments

Jarkko Sakkinen Nov. 15, 2022, 10:03 p.m. UTC | #1 
On Mon, Nov 07, 2022 at 02:02:10PM -0800, Haitao Huang wrote:
> Support madvise(..., MADV_WILLNEED) by adding EPC pages with EAUG in
> the newly added fops->fadvise() callback implementation, sgx_fadvise().
> 
> Change the return type and values of the sgx_encl_eaug_page function
> so that more specific error codes are returned for different treatment
> by the page fault handler and the fadvise callback.
> On any error, sgx_fadvise() will discontinue further operations
> and return as normal. The page fault handler allows a PF retried
> by returning VM_FAULT_NOPAGE in handling -EBUSY returned from
> sgx_encl_eaug_page.
> 
> Signed-off-by: Haitao Huang <haitao.huang@linux.intel.com>
> ---
>  arch/x86/kernel/cpu/sgx/driver.c | 76 ++++++++++++++++++++++++++++++++
>  arch/x86/kernel/cpu/sgx/encl.c   | 46 ++++++++++++-------
>  arch/x86/kernel/cpu/sgx/encl.h   |  4 +-
>  3 files changed, 108 insertions(+), 18 deletions(-)
> 
> diff --git a/arch/x86/kernel/cpu/sgx/driver.c b/arch/x86/kernel/cpu/sgx/driver.c
> index aa9b8b868867..dec2e9691ae3 100644
> --- a/arch/x86/kernel/cpu/sgx/driver.c
> +++ b/arch/x86/kernel/cpu/sgx/driver.c
> @@ -2,6 +2,7 @@
>  /*  Copyright(c) 2016-20 Intel Corporation. */
>  
>  #include <linux/acpi.h>
> +#include <linux/fadvise.h>
>  #include <linux/miscdevice.h>
>  #include <linux/mman.h>
>  #include <linux/security.h>
> @@ -9,6 +10,7 @@
>  #include <asm/traps.h>
>  #include "driver.h"
>  #include "encl.h"
> +#include "encls.h"
>  
>  u64 sgx_attributes_reserved_mask;
>  u64 sgx_xfrm_reserved_mask = ~0x3;
> @@ -97,10 +99,83 @@ static int sgx_mmap(struct file *file, struct vm_area_struct *vma)
>  	vma->vm_ops = &sgx_vm_ops;
>  	vma->vm_flags |= VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP | VM_IO;
>  	vma->vm_private_data = encl;
> +	vma->vm_pgoff = PFN_DOWN(vma->vm_start - encl->base);
>  
>  	return 0;
>  }
>  
> +/*
> + * Add new pages to the enclave sequentially with ENCLS[EAUG] for the WILLNEED advice.
> + * Only do this to existing VMAs in the same enclave and reject the request otherwise.
> + */
> +static int sgx_fadvise(struct file *file, loff_t offset, loff_t len, int advice)
> +{
> +	struct sgx_encl *encl = file->private_data;
> +	struct vm_area_struct *vma = NULL;
> +	unsigned long start, end, pos;
> +	int ret = -EINVAL;
> +
> +	/* Only support WILLNEED */
> +	if (advice != POSIX_FADV_WILLNEED)
> +		return -EINVAL;
> +	if (!encl)
> +		return -EINVAL;

Why !encl check is needed?

> +	if (!cpu_feature_enabled(X86_FEATURE_SGX2))
> +		return -EINVAL;

This should be done first before doing anything else in the function.

> +
> +	if (offset + len < offset)
> +		return -EINVAL;
> +	if (encl->base + offset < encl->base)
> +		return -EINVAL;
> +	start  = offset + encl->base;
> +	end = start + len;

These could be just as well assigned in the declarations, which would
definitely be also less convoluted.

> +	if (end < start)
> +		return -EINVAL;
> +	if (end > encl->base + encl->size)
> +		return -EINVAL;
> +
> +	if (!test_bit(SGX_ENCL_INITIALIZED, &encl->flags))
> +		return -EINVAL;
> +
> +	mmap_read_lock(current->mm);
> +
> +	vma = find_vma(current->mm, start);
> +	if (!vma)
> +		goto unlock;
> +	if (vma->vm_private_data != encl)
> +		goto unlock;
> +
> +	pos = start;
> +	if (pos < vma->vm_start || end > vma->vm_end) {
> +		/* Don't allow any gaps */
> +		goto unlock;
> +	}
> +
> +	/* Here: vm_start <= pos < end <= vm_end */
> +	while (pos < end) {
> +		if (xa_load(&encl->page_array, PFN_DOWN(pos)))
> +			continue;
> +		if (signal_pending(current)) {
> +			if (pos == start)
> +				ret = -ERESTARTSYS;
> +			else
> +				ret = -EINTR;
> +			goto unlock;
> +		}
> +		ret = sgx_encl_eaug_page(vma, encl, pos);
> +		/* It's OK to not finish */
> +		if (ret)
> +			break;
> +		pos = pos + PAGE_SIZE;
> +		cond_resched();
> +	}
> +	ret = 0;
> +
> +unlock:
> +	mmap_read_unlock(current->mm);
> +	return ret;
> +}
> +
>  static unsigned long sgx_get_unmapped_area(struct file *file,
>  					   unsigned long addr,
>  					   unsigned long len,
> @@ -133,6 +208,7 @@ static const struct file_operations sgx_encl_fops = {
>  	.compat_ioctl		= sgx_compat_ioctl,
>  #endif
>  	.mmap			= sgx_mmap,
> +	.fadvise		= sgx_fadvise,
>  	.get_unmapped_area	= sgx_get_unmapped_area,
>  };
>  
> diff --git a/arch/x86/kernel/cpu/sgx/encl.c b/arch/x86/kernel/cpu/sgx/encl.c
> index 1abc5e7f2660..c57e60d5a0aa 100644
> --- a/arch/x86/kernel/cpu/sgx/encl.c
> +++ b/arch/x86/kernel/cpu/sgx/encl.c
> @@ -305,11 +305,11 @@ struct sgx_encl_page *sgx_encl_load_page(struct sgx_encl *encl,
>   * on a SGX2 system then the EPC can be added dynamically via the SGX2
>   * ENCLS[EAUG] instruction.
>   *
> - * Returns: Appropriate vm_fault_t: VM_FAULT_NOPAGE when PTE was installed
> - * successfully, VM_FAULT_SIGBUS or VM_FAULT_OOM as error otherwise.
> + * Returns: 0 when PTE was installed successfully, -EBUSY for waiting on
> + * reclaimer to free EPC, -ENOMEM for out of RAM, -EFAULT as error otherwise.
>   */
> -vm_fault_t sgx_encl_eaug_page(struct vm_area_struct *vma,
> -			      struct sgx_encl *encl, unsigned long addr)
> +int sgx_encl_eaug_page(struct vm_area_struct *vma,
> +		       struct sgx_encl *encl, unsigned long addr)
>  {
>  	vm_fault_t vmret = VM_FAULT_SIGBUS;
>  	struct sgx_pageinfo pginfo = {0};
> @@ -318,10 +318,10 @@ vm_fault_t sgx_encl_eaug_page(struct vm_area_struct *vma,
>  	struct sgx_va_page *va_page;
>  	unsigned long phys_addr;
>  	u64 secinfo_flags;
> -	int ret;
> +	int ret = -EFAULT;

Why?

>  
>  	if (!test_bit(SGX_ENCL_INITIALIZED, &encl->flags))
> -		return VM_FAULT_SIGBUS;
> +		return -EFAULT;
>  
>  	/*
>  	 * Ignore internal permission checking for dynamically added pages.
> @@ -332,21 +332,21 @@ vm_fault_t sgx_encl_eaug_page(struct vm_area_struct *vma,
>  	secinfo_flags = SGX_SECINFO_R | SGX_SECINFO_W | SGX_SECINFO_X;
>  	encl_page = sgx_encl_page_alloc(encl, addr - encl->base, secinfo_flags);
>  	if (IS_ERR(encl_page))
> -		return VM_FAULT_OOM;
> +		return -ENOMEM;
>  
>  	mutex_lock(&encl->lock);
>  
>  	epc_page = sgx_alloc_epc_page(encl_page, false);
>  	if (IS_ERR(epc_page)) {
>  		if (PTR_ERR(epc_page) == -EBUSY)
> -			vmret =  VM_FAULT_NOPAGE;
> +			ret =  -EBUSY;
>  		goto err_out_unlock;
>  	}
>  
>  	va_page = sgx_encl_grow(encl, false);
>  	if (IS_ERR(va_page)) {
>  		if (PTR_ERR(va_page) == -EBUSY)
> -			vmret = VM_FAULT_NOPAGE;
> +			ret = -EBUSY;
>  		goto err_out_epc;
>  	}
>  
> @@ -359,16 +359,20 @@ vm_fault_t sgx_encl_eaug_page(struct vm_area_struct *vma,
>  	 * If ret == -EBUSY then page was created in another flow while
>  	 * running without encl->lock
>  	 */
> -	if (ret)
> +	if (ret) {
> +		ret = -EFAULT;
>  		goto err_out_shrink;
> +	}
>  
>  	pginfo.secs = (unsigned long)sgx_get_epc_virt_addr(encl->secs.epc_page);
>  	pginfo.addr = encl_page->desc & PAGE_MASK;
>  	pginfo.metadata = 0;
>  
>  	ret = __eaug(&pginfo, sgx_get_epc_virt_addr(epc_page));
> -	if (ret)
> +	if (ret) {
> +		ret = -EFAULT;
>  		goto err_out;
> +	}
>  
>  	encl_page->encl = encl;
>  	encl_page->epc_page = epc_page;
> @@ -385,10 +389,10 @@ vm_fault_t sgx_encl_eaug_page(struct vm_area_struct *vma,
>  	vmret = vmf_insert_pfn(vma, addr, PFN_DOWN(phys_addr));
>  	if (vmret != VM_FAULT_NOPAGE) {
>  		mutex_unlock(&encl->lock);
> -		return VM_FAULT_SIGBUS;
> +		return -EFAULT;
>  	}
>  	mutex_unlock(&encl->lock);
> -	return VM_FAULT_NOPAGE;
> +	return 0;
>  
>  err_out:
>  	xa_erase(&encl->page_array, PFN_DOWN(encl_page->desc));
> @@ -401,7 +405,7 @@ vm_fault_t sgx_encl_eaug_page(struct vm_area_struct *vma,
>  	mutex_unlock(&encl->lock);
>  	kfree(encl_page);
>  
> -	return vmret;
> +	return ret;
>  }
>  
>  static vm_fault_t sgx_vma_fault(struct vm_fault *vmf)
> @@ -431,8 +435,18 @@ static vm_fault_t sgx_vma_fault(struct vm_fault *vmf)
>  	 * enclave that will be checked for right away.
>  	 */
>  	if (cpu_feature_enabled(X86_FEATURE_SGX2) &&
> -	    (!xa_load(&encl->page_array, PFN_DOWN(addr))))
> -		return sgx_encl_eaug_page(vma, encl, addr);
> +	    (!xa_load(&encl->page_array, PFN_DOWN(addr)))) {
> +		switch (sgx_encl_eaug_page(vma, encl, addr)) {
> +		case 0:
> +		case -EBUSY:
> +			return VM_FAULT_NOPAGE;
> +		case -ENOMEM:
> +			return VM_FAULT_OOM;
> +		case -EFAULT:
> +		default:
> +			return VM_FAULT_SIGBUS;
> +		}
> +	}
>  
>  	mutex_lock(&encl->lock);
>  
> diff --git a/arch/x86/kernel/cpu/sgx/encl.h b/arch/x86/kernel/cpu/sgx/encl.h
> index 557d4abb13fc..5a351e2ece5e 100644
> --- a/arch/x86/kernel/cpu/sgx/encl.h
> +++ b/arch/x86/kernel/cpu/sgx/encl.h
> @@ -127,7 +127,7 @@ struct sgx_encl_page *sgx_encl_load_page(struct sgx_encl *encl,
>  					 unsigned long addr);
>  struct sgx_va_page *sgx_encl_grow(struct sgx_encl *encl, bool reclaim);
>  void sgx_encl_shrink(struct sgx_encl *encl, struct sgx_va_page *va_page);
> -vm_fault_t sgx_encl_eaug_page(struct vm_area_struct *vma,
> -			      struct sgx_encl *encl, unsigned long addr);
> +int sgx_encl_eaug_page(struct vm_area_struct *vma,
> +		       struct sgx_encl *encl, unsigned long addr);
>  
>  #endif /* _X86_ENCL_H */
> -- 
> 2.25.1
> 

BR, Jarkko
Haitao Huang Jan. 25, 2023, 7:40 p.m. UTC | #2 
On Tue, 15 Nov 2022 16:03:45 -0600, Jarkko Sakkinen <jarkko@kernel.org>  
wrote:


>> +	if (!encl)
>> +		return -EINVAL;
>
> Why !encl check is needed?
It was intended as sanity check. But I think encl should not be null at  
this point so will remove in next version.

>
>> +	if (!cpu_feature_enabled(X86_FEATURE_SGX2))
>> +		return -EINVAL;
>
> This should be done first before doing anything else in the function.

Will do

>
>> +
>> +	if (offset + len < offset)
>> +		return -EINVAL;
>> +	if (encl->base + offset < encl->base)
>> +		return -EINVAL;
>> +	start  = offset + encl->base;
>> +	end = start + len;
>
> These could be just as well assigned in the declarations, which would
> definitely be also less convoluted.
>
Will do

...
>> diff --git a/arch/x86/kernel/cpu/sgx/encl.c  
>> b/arch/x86/kernel/cpu/sgx/encl.c
>> index 1abc5e7f2660..c57e60d5a0aa 100644
>> --- a/arch/x86/kernel/cpu/sgx/encl.c
>> +++ b/arch/x86/kernel/cpu/sgx/encl.c
>> @@ -305,11 +305,11 @@ struct sgx_encl_page *sgx_encl_load_page(struct  
>> sgx_encl *encl,
>>   * on a SGX2 system then the EPC can be added dynamically via the SGX2
>>   * ENCLS[EAUG] instruction.
>>   *
>> - * Returns: Appropriate vm_fault_t: VM_FAULT_NOPAGE when PTE was  
>> installed
>> - * successfully, VM_FAULT_SIGBUS or VM_FAULT_OOM as error otherwise.
>> + * Returns: 0 when PTE was installed successfully, -EBUSY for waiting  
>> on
>> + * reclaimer to free EPC, -ENOMEM for out of RAM, -EFAULT as error  
>> otherwise.
>>   */
>> -vm_fault_t sgx_encl_eaug_page(struct vm_area_struct *vma,
>> -			      struct sgx_encl *encl, unsigned long addr)
>> +int sgx_encl_eaug_page(struct vm_area_struct *vma,
>> +		       struct sgx_encl *encl, unsigned long addr)
>>  {
>>  	vm_fault_t vmret = VM_FAULT_SIGBUS;
>>  	struct sgx_pageinfo pginfo = {0};
>> @@ -318,10 +318,10 @@ vm_fault_t sgx_encl_eaug_page(struct  
>> vm_area_struct *vma,
>>  	struct sgx_va_page *va_page;
>>  	unsigned long phys_addr;
>>  	u64 secinfo_flags;
>> -	int ret;
>> +	int ret = -EFAULT;
>
> Why?
Original code uses ret only to temporarily store return values from the  
called functions.
Now I also use it as return of this function and assign -EFAULT as default
in all cases that ret is not assigned explicitly below, e.g., -EBUSY cases.
Basically -EFAULT cases are the same as VM_FAULT_SIGBUS cases in original  
code.
I'll clarify in comments above for the return values.

Thanks
Haitao
Jarkko Sakkinen Jan. 26, 2023, 9:24 p.m. UTC | #3 
On Wed, Jan 25, 2023 at 01:40:39PM -0600, Haitao Huang wrote:
> On Tue, 15 Nov 2022 16:03:45 -0600, Jarkko Sakkinen <jarkko@kernel.org>
> wrote:
> 
> 
> > > +	if (!encl)
> > > +		return -EINVAL;
> > 
> > Why !encl check is needed?
> It was intended as sanity check. But I think encl should not be null at this
> point so will remove in next version.
> 
> > 
> > > +	if (!cpu_feature_enabled(X86_FEATURE_SGX2))
> > > +		return -EINVAL;
> > 
> > This should be done first before doing anything else in the function.
> 
> Will do
> 
> > 
> > > +
> > > +	if (offset + len < offset)
> > > +		return -EINVAL;
> > > +	if (encl->base + offset < encl->base)
> > > +		return -EINVAL;
> > > +	start  = offset + encl->base;
> > > +	end = start + len;
> > 
> > These could be just as well assigned in the declarations, which would
> > definitely be also less convoluted.
> > 
> Will do
> 
> ...
> > > diff --git a/arch/x86/kernel/cpu/sgx/encl.c
> > > b/arch/x86/kernel/cpu/sgx/encl.c
> > > index 1abc5e7f2660..c57e60d5a0aa 100644
> > > --- a/arch/x86/kernel/cpu/sgx/encl.c
> > > +++ b/arch/x86/kernel/cpu/sgx/encl.c
> > > @@ -305,11 +305,11 @@ struct sgx_encl_page
> > > *sgx_encl_load_page(struct sgx_encl *encl,
> > >   * on a SGX2 system then the EPC can be added dynamically via the SGX2
> > >   * ENCLS[EAUG] instruction.
> > >   *
> > > - * Returns: Appropriate vm_fault_t: VM_FAULT_NOPAGE when PTE was
> > > installed
> > > - * successfully, VM_FAULT_SIGBUS or VM_FAULT_OOM as error otherwise.
> > > + * Returns: 0 when PTE was installed successfully, -EBUSY for
> > > waiting on
> > > + * reclaimer to free EPC, -ENOMEM for out of RAM, -EFAULT as error
> > > otherwise.
> > >   */
> > > -vm_fault_t sgx_encl_eaug_page(struct vm_area_struct *vma,
> > > -			      struct sgx_encl *encl, unsigned long addr)
> > > +int sgx_encl_eaug_page(struct vm_area_struct *vma,
> > > +		       struct sgx_encl *encl, unsigned long addr)
> > >  {
> > >  	vm_fault_t vmret = VM_FAULT_SIGBUS;
> > >  	struct sgx_pageinfo pginfo = {0};
> > > @@ -318,10 +318,10 @@ vm_fault_t sgx_encl_eaug_page(struct
> > > vm_area_struct *vma,
> > >  	struct sgx_va_page *va_page;
> > >  	unsigned long phys_addr;
> > >  	u64 secinfo_flags;
> > > -	int ret;
> > > +	int ret = -EFAULT;
> > 
> > Why?
> Original code uses ret only to temporarily store return values from the
> called functions.
> Now I also use it as return of this function and assign -EFAULT as default
> in all cases that ret is not assigned explicitly below, e.g., -EBUSY cases.
> Basically -EFAULT cases are the same as VM_FAULT_SIGBUS cases in original
> code.
> I'll clarify in comments above for the return values.
> 
> Thanks
> Haitao

OK, will look forward to it.

BR, Jarkko
diff mbox series

Patch

diff --git a/arch/x86/kernel/cpu/sgx/driver.c b/arch/x86/kernel/cpu/sgx/driver.c
index aa9b8b868867..dec2e9691ae3 100644
--- a/arch/x86/kernel/cpu/sgx/driver.c
+++ b/arch/x86/kernel/cpu/sgx/driver.c
@@ -2,6 +2,7 @@ 
 /*  Copyright(c) 2016-20 Intel Corporation. */
 
 #include <linux/acpi.h>
+#include <linux/fadvise.h>
 #include <linux/miscdevice.h>
 #include <linux/mman.h>
 #include <linux/security.h>
@@ -9,6 +10,7 @@ 
 #include <asm/traps.h>
 #include "driver.h"
 #include "encl.h"
+#include "encls.h"
 
 u64 sgx_attributes_reserved_mask;
 u64 sgx_xfrm_reserved_mask = ~0x3;
@@ -97,10 +99,83 @@  static int sgx_mmap(struct file *file, struct vm_area_struct *vma)
 	vma->vm_ops = &sgx_vm_ops;
 	vma->vm_flags |= VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP | VM_IO;
 	vma->vm_private_data = encl;
+	vma->vm_pgoff = PFN_DOWN(vma->vm_start - encl->base);
 
 	return 0;
 }
 
+/*
+ * Add new pages to the enclave sequentially with ENCLS[EAUG] for the WILLNEED advice.
+ * Only do this to existing VMAs in the same enclave and reject the request otherwise.
+ */
+static int sgx_fadvise(struct file *file, loff_t offset, loff_t len, int advice)
+{
+	struct sgx_encl *encl = file->private_data;
+	struct vm_area_struct *vma = NULL;
+	unsigned long start, end, pos;
+	int ret = -EINVAL;
+
+	/* Only support WILLNEED */
+	if (advice != POSIX_FADV_WILLNEED)
+		return -EINVAL;
+	if (!encl)
+		return -EINVAL;
+	if (!cpu_feature_enabled(X86_FEATURE_SGX2))
+		return -EINVAL;
+
+	if (offset + len < offset)
+		return -EINVAL;
+	if (encl->base + offset < encl->base)
+		return -EINVAL;
+	start  = offset + encl->base;
+	end = start + len;
+	if (end < start)
+		return -EINVAL;
+	if (end > encl->base + encl->size)
+		return -EINVAL;
+
+	if (!test_bit(SGX_ENCL_INITIALIZED, &encl->flags))
+		return -EINVAL;
+
+	mmap_read_lock(current->mm);
+
+	vma = find_vma(current->mm, start);
+	if (!vma)
+		goto unlock;
+	if (vma->vm_private_data != encl)
+		goto unlock;
+
+	pos = start;
+	if (pos < vma->vm_start || end > vma->vm_end) {
+		/* Don't allow any gaps */
+		goto unlock;
+	}
+
+	/* Here: vm_start <= pos < end <= vm_end */
+	while (pos < end) {
+		if (xa_load(&encl->page_array, PFN_DOWN(pos)))
+			continue;
+		if (signal_pending(current)) {
+			if (pos == start)
+				ret = -ERESTARTSYS;
+			else
+				ret = -EINTR;
+			goto unlock;
+		}
+		ret = sgx_encl_eaug_page(vma, encl, pos);
+		/* It's OK to not finish */
+		if (ret)
+			break;
+		pos = pos + PAGE_SIZE;
+		cond_resched();
+	}
+	ret = 0;
+
+unlock:
+	mmap_read_unlock(current->mm);
+	return ret;
+}
+
 static unsigned long sgx_get_unmapped_area(struct file *file,
 					   unsigned long addr,
 					   unsigned long len,
@@ -133,6 +208,7 @@  static const struct file_operations sgx_encl_fops = {
 	.compat_ioctl		= sgx_compat_ioctl,
 #endif
 	.mmap			= sgx_mmap,
+	.fadvise		= sgx_fadvise,
 	.get_unmapped_area	= sgx_get_unmapped_area,
 };
 
diff --git a/arch/x86/kernel/cpu/sgx/encl.c b/arch/x86/kernel/cpu/sgx/encl.c
index 1abc5e7f2660..c57e60d5a0aa 100644
--- a/arch/x86/kernel/cpu/sgx/encl.c
+++ b/arch/x86/kernel/cpu/sgx/encl.c
@@ -305,11 +305,11 @@  struct sgx_encl_page *sgx_encl_load_page(struct sgx_encl *encl,
  * on a SGX2 system then the EPC can be added dynamically via the SGX2
  * ENCLS[EAUG] instruction.
  *
- * Returns: Appropriate vm_fault_t: VM_FAULT_NOPAGE when PTE was installed
- * successfully, VM_FAULT_SIGBUS or VM_FAULT_OOM as error otherwise.
+ * Returns: 0 when PTE was installed successfully, -EBUSY for waiting on
+ * reclaimer to free EPC, -ENOMEM for out of RAM, -EFAULT as error otherwise.
  */
-vm_fault_t sgx_encl_eaug_page(struct vm_area_struct *vma,
-			      struct sgx_encl *encl, unsigned long addr)
+int sgx_encl_eaug_page(struct vm_area_struct *vma,
+		       struct sgx_encl *encl, unsigned long addr)
 {
 	vm_fault_t vmret = VM_FAULT_SIGBUS;
 	struct sgx_pageinfo pginfo = {0};
@@ -318,10 +318,10 @@  vm_fault_t sgx_encl_eaug_page(struct vm_area_struct *vma,
 	struct sgx_va_page *va_page;
 	unsigned long phys_addr;
 	u64 secinfo_flags;
-	int ret;
+	int ret = -EFAULT;
 
 	if (!test_bit(SGX_ENCL_INITIALIZED, &encl->flags))
-		return VM_FAULT_SIGBUS;
+		return -EFAULT;
 
 	/*
 	 * Ignore internal permission checking for dynamically added pages.
@@ -332,21 +332,21 @@  vm_fault_t sgx_encl_eaug_page(struct vm_area_struct *vma,
 	secinfo_flags = SGX_SECINFO_R | SGX_SECINFO_W | SGX_SECINFO_X;
 	encl_page = sgx_encl_page_alloc(encl, addr - encl->base, secinfo_flags);
 	if (IS_ERR(encl_page))
-		return VM_FAULT_OOM;
+		return -ENOMEM;
 
 	mutex_lock(&encl->lock);
 
 	epc_page = sgx_alloc_epc_page(encl_page, false);
 	if (IS_ERR(epc_page)) {
 		if (PTR_ERR(epc_page) == -EBUSY)
-			vmret =  VM_FAULT_NOPAGE;
+			ret =  -EBUSY;
 		goto err_out_unlock;
 	}
 
 	va_page = sgx_encl_grow(encl, false);
 	if (IS_ERR(va_page)) {
 		if (PTR_ERR(va_page) == -EBUSY)
-			vmret = VM_FAULT_NOPAGE;
+			ret = -EBUSY;
 		goto err_out_epc;
 	}
 
@@ -359,16 +359,20 @@  vm_fault_t sgx_encl_eaug_page(struct vm_area_struct *vma,
 	 * If ret == -EBUSY then page was created in another flow while
 	 * running without encl->lock
 	 */
-	if (ret)
+	if (ret) {
+		ret = -EFAULT;
 		goto err_out_shrink;
+	}
 
 	pginfo.secs = (unsigned long)sgx_get_epc_virt_addr(encl->secs.epc_page);
 	pginfo.addr = encl_page->desc & PAGE_MASK;
 	pginfo.metadata = 0;
 
 	ret = __eaug(&pginfo, sgx_get_epc_virt_addr(epc_page));
-	if (ret)
+	if (ret) {
+		ret = -EFAULT;
 		goto err_out;
+	}
 
 	encl_page->encl = encl;
 	encl_page->epc_page = epc_page;
@@ -385,10 +389,10 @@  vm_fault_t sgx_encl_eaug_page(struct vm_area_struct *vma,
 	vmret = vmf_insert_pfn(vma, addr, PFN_DOWN(phys_addr));
 	if (vmret != VM_FAULT_NOPAGE) {
 		mutex_unlock(&encl->lock);
-		return VM_FAULT_SIGBUS;
+		return -EFAULT;
 	}
 	mutex_unlock(&encl->lock);
-	return VM_FAULT_NOPAGE;
+	return 0;
 
 err_out:
 	xa_erase(&encl->page_array, PFN_DOWN(encl_page->desc));
@@ -401,7 +405,7 @@  vm_fault_t sgx_encl_eaug_page(struct vm_area_struct *vma,
 	mutex_unlock(&encl->lock);
 	kfree(encl_page);
 
-	return vmret;
+	return ret;
 }
 
 static vm_fault_t sgx_vma_fault(struct vm_fault *vmf)
@@ -431,8 +435,18 @@  static vm_fault_t sgx_vma_fault(struct vm_fault *vmf)
 	 * enclave that will be checked for right away.
 	 */
 	if (cpu_feature_enabled(X86_FEATURE_SGX2) &&
-	    (!xa_load(&encl->page_array, PFN_DOWN(addr))))
-		return sgx_encl_eaug_page(vma, encl, addr);
+	    (!xa_load(&encl->page_array, PFN_DOWN(addr)))) {
+		switch (sgx_encl_eaug_page(vma, encl, addr)) {
+		case 0:
+		case -EBUSY:
+			return VM_FAULT_NOPAGE;
+		case -ENOMEM:
+			return VM_FAULT_OOM;
+		case -EFAULT:
+		default:
+			return VM_FAULT_SIGBUS;
+		}
+	}
 
 	mutex_lock(&encl->lock);
 
diff --git a/arch/x86/kernel/cpu/sgx/encl.h b/arch/x86/kernel/cpu/sgx/encl.h
index 557d4abb13fc..5a351e2ece5e 100644
--- a/arch/x86/kernel/cpu/sgx/encl.h
+++ b/arch/x86/kernel/cpu/sgx/encl.h
@@ -127,7 +127,7 @@  struct sgx_encl_page *sgx_encl_load_page(struct sgx_encl *encl,
 					 unsigned long addr);
 struct sgx_va_page *sgx_encl_grow(struct sgx_encl *encl, bool reclaim);
 void sgx_encl_shrink(struct sgx_encl *encl, struct sgx_va_page *va_page);
-vm_fault_t sgx_encl_eaug_page(struct vm_area_struct *vma,
-			      struct sgx_encl *encl, unsigned long addr);
+int sgx_encl_eaug_page(struct vm_area_struct *vma,
+		       struct sgx_encl *encl, unsigned long addr);
 
 #endif /* _X86_ENCL_H */