Messages in this thread Patch in this message | | | From | Tony Luck <> | Subject | [PATCH v11 1/7] x86/sgx: Add new sgx_epc_page flag bit to mark free pages | Date | Tue, 26 Oct 2021 15:00:44 -0700 |
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SGX EPC pages go through the following life cycle:
DIRTY ---> FREE ---> IN-USE --\ ^ | \-----------------/
Recovery action for poison for a DIRTY or FREE page is simple. Just make sure never to allocate the page. IN-USE pages need some extra handling.
Add a new flag bit SGX_EPC_PAGE_IS_FREE that is set when a page is added to a free list and cleared when the page is allocated.
Notes:
1) These transitions are made while holding the node->lock so that future code that checks the flags while holding the node->lock can be sure that if the SGX_EPC_PAGE_IS_FREE bit is set, then the page is on the free list.
2) Initially while the pages are on the dirty list the SGX_EPC_PAGE_IS_FREE bit is cleared.
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org> Tested-by: Reinette Chatre <reinette.chatre@intel.com> Signed-off-by: Tony Luck <tony.luck@intel.com> --- arch/x86/kernel/cpu/sgx/main.c | 2 ++ arch/x86/kernel/cpu/sgx/sgx.h | 3 +++ 2 files changed, 5 insertions(+)
diff --git a/arch/x86/kernel/cpu/sgx/main.c b/arch/x86/kernel/cpu/sgx/main.c index 63d3de02bbcc..825aa91516c8 100644 --- a/arch/x86/kernel/cpu/sgx/main.c +++ b/arch/x86/kernel/cpu/sgx/main.c @@ -472,6 +472,7 @@ static struct sgx_epc_page *__sgx_alloc_epc_page_from_node(int nid) page = list_first_entry(&node->free_page_list, struct sgx_epc_page, list); list_del_init(&page->list); sgx_nr_free_pages--; + page->flags = 0; spin_unlock(&node->lock); @@ -626,6 +627,7 @@ void sgx_free_epc_page(struct sgx_epc_page *page) list_add_tail(&page->list, &node->free_page_list); sgx_nr_free_pages++; + page->flags = SGX_EPC_PAGE_IS_FREE; spin_unlock(&node->lock); } diff --git a/arch/x86/kernel/cpu/sgx/sgx.h b/arch/x86/kernel/cpu/sgx/sgx.h index 4628acec0009..5906471156c5 100644 --- a/arch/x86/kernel/cpu/sgx/sgx.h +++ b/arch/x86/kernel/cpu/sgx/sgx.h @@ -26,6 +26,9 @@ /* Pages, which are being tracked by the page reclaimer. */ #define SGX_EPC_PAGE_RECLAIMER_TRACKED BIT(0) +/* Pages on free list */ +#define SGX_EPC_PAGE_IS_FREE BIT(1) + struct sgx_epc_page { unsigned int section; unsigned int flags; -- 2.31.1
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