diff mbox series

[06/26] x86/sgx: Introduce RECLAIM_IN_PROGRESS flag for EPC pages

Message ID 20221111183532.3676646-7-kristen@linux.intel.com
State New
Headers
Series Add Cgroup support for SGX EPC memory |

Commit Message

Kristen Carlson Accardi Nov. 11, 2022, 6:35 p.m. UTC 
  From: Sean Christopherson <sean.j.christopherson@intel.com>

Keep track of whether the EPC page is in the middle of being reclaimed
and do not delete the page off the it's LRU if it has not yet finished
being reclaimed.

Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Kristen Carlson Accardi <kristen@linux.intel.com>
Cc: Sean Christopherson <seanjc@google.com>
---
 arch/x86/kernel/cpu/sgx/main.c | 14 +++++++++-----
 arch/x86/kernel/cpu/sgx/sgx.h  |  4 ++++
 2 files changed, 13 insertions(+), 5 deletions(-)

Comments

Jarkko Sakkinen Nov. 15, 2022, 11:42 p.m. UTC | #1 
On Fri, Nov 11, 2022 at 10:35:11AM -0800, Kristen Carlson Accardi wrote:
> From: Sean Christopherson <sean.j.christopherson@intel.com>
> 
> Keep track of whether the EPC page is in the middle of being reclaimed
> and do not delete the page off the it's LRU if it has not yet finished

"off the it's LRU" ?

> being reclaimed.

I'm not sure how the description makes the change understandable.

> 
> Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
> Signed-off-by: Kristen Carlson Accardi <kristen@linux.intel.com>
> Cc: Sean Christopherson <seanjc@google.com>
> ---
>  arch/x86/kernel/cpu/sgx/main.c | 14 +++++++++-----
>  arch/x86/kernel/cpu/sgx/sgx.h  |  4 ++++
>  2 files changed, 13 insertions(+), 5 deletions(-)
> 
> diff --git a/arch/x86/kernel/cpu/sgx/main.c b/arch/x86/kernel/cpu/sgx/main.c
> index 3b09433ffd85..8c451071fa91 100644
> --- a/arch/x86/kernel/cpu/sgx/main.c
> +++ b/arch/x86/kernel/cpu/sgx/main.c
> @@ -305,13 +305,15 @@ static void __sgx_reclaim_pages(void)
>  
>  		encl_page = epc_page->encl_owner;
>  
> -		if (kref_get_unless_zero(&encl_page->encl->refcount) != 0)
> +		if (kref_get_unless_zero(&encl_page->encl->refcount) != 0) {
> +			epc_page->flags |= SGX_EPC_PAGE_RECLAIM_IN_PROGRESS;
>  			chunk[cnt++] = epc_page;
> -		else
> +		} else {
>  			/* The owner is freeing the page. No need to add the
>  			 * page back to the list of reclaimable pages.
>  			 */
>  			epc_page->flags &= ~SGX_EPC_PAGE_RECLAIMER_TRACKED;
> +		}
>  	}
>  	spin_unlock(&sgx_global_lru.lock);
>  
> @@ -337,6 +339,7 @@ static void __sgx_reclaim_pages(void)
>  
>  skip:
>  		spin_lock(&sgx_global_lru.lock);
> +		epc_page->flags &= ~SGX_EPC_PAGE_RECLAIM_IN_PROGRESS;
>  		sgx_epc_push_reclaimable(&sgx_global_lru, epc_page);
>  		spin_unlock(&sgx_global_lru.lock);
>  
> @@ -360,7 +363,8 @@ static void __sgx_reclaim_pages(void)
>  		sgx_reclaimer_write(epc_page, &backing[i]);
>  
>  		kref_put(&encl_page->encl->refcount, sgx_encl_release);
> -		epc_page->flags &= ~SGX_EPC_PAGE_RECLAIMER_TRACKED;
> +		epc_page->flags &= ~(SGX_EPC_PAGE_RECLAIMER_TRACKED |
> +				     SGX_EPC_PAGE_RECLAIM_IN_PROGRESS);
>  
>  		sgx_free_epc_page(epc_page);
>  	}
> @@ -508,7 +512,7 @@ struct sgx_epc_page *__sgx_alloc_epc_page(void)
>  void sgx_record_epc_page(struct sgx_epc_page *page, unsigned long flags)
>  {
>  	spin_lock(&sgx_global_lru.lock);
> -	WARN_ON(page->flags & SGX_EPC_PAGE_RECLAIMER_TRACKED);
> +	WARN_ON(page->flags & SGX_EPC_PAGE_RECLAIM_FLAGS);

Please, open code SGX_EPC_PAGE_RECLAIM_FLAGS. It only adds unnecassry
need to cross-reference to the header file.

Also, please describe the changes on how state flags are used before
and after this patch to the commit message.

>  	page->flags |= flags;
>  	if (flags & SGX_EPC_PAGE_RECLAIMER_TRACKED)
>  		sgx_epc_push_reclaimable(&sgx_global_lru, page);
> @@ -532,7 +536,7 @@ int sgx_drop_epc_page(struct sgx_epc_page *page)
>  	spin_lock(&sgx_global_lru.lock);
>  	if (page->flags & SGX_EPC_PAGE_RECLAIMER_TRACKED) {
>  		/* The page is being reclaimed. */
> -		if (list_empty(&page->list)) {
> +		if (page->flags & SGX_EPC_PAGE_RECLAIM_IN_PROGRESS) {
>  			spin_unlock(&sgx_global_lru.lock);
>  			return -EBUSY;
>  		}
> diff --git a/arch/x86/kernel/cpu/sgx/sgx.h b/arch/x86/kernel/cpu/sgx/sgx.h
> index 969606615211..04ca644928a8 100644
> --- a/arch/x86/kernel/cpu/sgx/sgx.h
> +++ b/arch/x86/kernel/cpu/sgx/sgx.h
> @@ -30,6 +30,10 @@
>  #define SGX_EPC_PAGE_IS_FREE		BIT(1)
>  /* Pages allocated for KVM guest */
>  #define SGX_EPC_PAGE_KVM_GUEST		BIT(2)
> +/* page flag to indicate reclaim is in progress */
> +#define SGX_EPC_PAGE_RECLAIM_IN_PROGRESS BIT(3)
> +#define SGX_EPC_PAGE_RECLAIM_FLAGS	(SGX_EPC_PAGE_RECLAIMER_TRACKED | \
> +					 SGX_EPC_PAGE_RECLAIM_IN_PROGRESS)
>  
>  struct sgx_epc_page {
>  	unsigned int section;
> -- 
> 2.37.3
> 

BR, Jarkko
diff mbox series

Patch

diff --git a/arch/x86/kernel/cpu/sgx/main.c b/arch/x86/kernel/cpu/sgx/main.c
index 3b09433ffd85..8c451071fa91 100644
--- a/arch/x86/kernel/cpu/sgx/main.c
+++ b/arch/x86/kernel/cpu/sgx/main.c
@@ -305,13 +305,15 @@  static void __sgx_reclaim_pages(void)
 
 		encl_page = epc_page->encl_owner;
 
-		if (kref_get_unless_zero(&encl_page->encl->refcount) != 0)
+		if (kref_get_unless_zero(&encl_page->encl->refcount) != 0) {
+			epc_page->flags |= SGX_EPC_PAGE_RECLAIM_IN_PROGRESS;
 			chunk[cnt++] = epc_page;
-		else
+		} else {
 			/* The owner is freeing the page. No need to add the
 			 * page back to the list of reclaimable pages.
 			 */
 			epc_page->flags &= ~SGX_EPC_PAGE_RECLAIMER_TRACKED;
+		}
 	}
 	spin_unlock(&sgx_global_lru.lock);
 
@@ -337,6 +339,7 @@  static void __sgx_reclaim_pages(void)
 
 skip:
 		spin_lock(&sgx_global_lru.lock);
+		epc_page->flags &= ~SGX_EPC_PAGE_RECLAIM_IN_PROGRESS;
 		sgx_epc_push_reclaimable(&sgx_global_lru, epc_page);
 		spin_unlock(&sgx_global_lru.lock);
 
@@ -360,7 +363,8 @@  static void __sgx_reclaim_pages(void)
 		sgx_reclaimer_write(epc_page, &backing[i]);
 
 		kref_put(&encl_page->encl->refcount, sgx_encl_release);
-		epc_page->flags &= ~SGX_EPC_PAGE_RECLAIMER_TRACKED;
+		epc_page->flags &= ~(SGX_EPC_PAGE_RECLAIMER_TRACKED |
+				     SGX_EPC_PAGE_RECLAIM_IN_PROGRESS);
 
 		sgx_free_epc_page(epc_page);
 	}
@@ -508,7 +512,7 @@  struct sgx_epc_page *__sgx_alloc_epc_page(void)
 void sgx_record_epc_page(struct sgx_epc_page *page, unsigned long flags)
 {
 	spin_lock(&sgx_global_lru.lock);
-	WARN_ON(page->flags & SGX_EPC_PAGE_RECLAIMER_TRACKED);
+	WARN_ON(page->flags & SGX_EPC_PAGE_RECLAIM_FLAGS);
 	page->flags |= flags;
 	if (flags & SGX_EPC_PAGE_RECLAIMER_TRACKED)
 		sgx_epc_push_reclaimable(&sgx_global_lru, page);
@@ -532,7 +536,7 @@  int sgx_drop_epc_page(struct sgx_epc_page *page)
 	spin_lock(&sgx_global_lru.lock);
 	if (page->flags & SGX_EPC_PAGE_RECLAIMER_TRACKED) {
 		/* The page is being reclaimed. */
-		if (list_empty(&page->list)) {
+		if (page->flags & SGX_EPC_PAGE_RECLAIM_IN_PROGRESS) {
 			spin_unlock(&sgx_global_lru.lock);
 			return -EBUSY;
 		}
diff --git a/arch/x86/kernel/cpu/sgx/sgx.h b/arch/x86/kernel/cpu/sgx/sgx.h
index 969606615211..04ca644928a8 100644
--- a/arch/x86/kernel/cpu/sgx/sgx.h
+++ b/arch/x86/kernel/cpu/sgx/sgx.h
@@ -30,6 +30,10 @@ 
 #define SGX_EPC_PAGE_IS_FREE		BIT(1)
 /* Pages allocated for KVM guest */
 #define SGX_EPC_PAGE_KVM_GUEST		BIT(2)
+/* page flag to indicate reclaim is in progress */
+#define SGX_EPC_PAGE_RECLAIM_IN_PROGRESS BIT(3)
+#define SGX_EPC_PAGE_RECLAIM_FLAGS	(SGX_EPC_PAGE_RECLAIMER_TRACKED | \
+					 SGX_EPC_PAGE_RECLAIM_IN_PROGRESS)
 
 struct sgx_epc_page {
 	unsigned int section;