Messages in this thread Patch in this message | | | From | Tony Luck <> | Subject | [PATCH v2 1/6] x86/sgx: Provide indication of life-cycle of EPC pages | Date | Mon, 19 Jul 2021 11:20:04 -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.
It would be good to use the sgx_epc_page->owner field as an indicator of where an EPC page is currently in that cycle (owner != NULL means the EPC page is IN-USE). But there is one caller, sgx_alloc_va_page(), that calls with NULL.
Make the following changes:
1) Change the type of "owner" to "void *" (it can have other types besides "struct sgx_encl_page *). 2) Update sgx_alloc_va_page() to pass in a dummy non-NULL value in this case. 3) Add a check to sgx_free_epc_page() to prevent calling with NULL. 4) Reset owner to NULL in sgx_free_epc_page().
Signed-off-by: Tony Luck <tony.luck@intel.com> --- arch/x86/kernel/cpu/sgx/encl.c | 2 +- arch/x86/kernel/cpu/sgx/main.c | 6 ++++++ arch/x86/kernel/cpu/sgx/sgx.h | 2 +- 3 files changed, 8 insertions(+), 2 deletions(-)
diff --git a/arch/x86/kernel/cpu/sgx/encl.c b/arch/x86/kernel/cpu/sgx/encl.c index 001808e3901c..ca328d56d230 100644 --- a/arch/x86/kernel/cpu/sgx/encl.c +++ b/arch/x86/kernel/cpu/sgx/encl.c @@ -679,7 +679,7 @@ struct sgx_epc_page *sgx_alloc_va_page(void) struct sgx_epc_page *epc_page; int ret; - epc_page = sgx_alloc_epc_page(NULL, true); + epc_page = sgx_alloc_epc_page("Not NULL!", true); if (IS_ERR(epc_page)) return ERR_CAST(epc_page); diff --git a/arch/x86/kernel/cpu/sgx/main.c b/arch/x86/kernel/cpu/sgx/main.c index 63d3de02bbcc..d61bc1f635a1 100644 --- a/arch/x86/kernel/cpu/sgx/main.c +++ b/arch/x86/kernel/cpu/sgx/main.c @@ -578,6 +578,11 @@ struct sgx_epc_page *sgx_alloc_epc_page(void *owner, bool reclaim) { struct sgx_epc_page *page; + if (!owner) { + WARN_ON_ONCE(1); + return NULL; + } + for ( ; ; ) { page = __sgx_alloc_epc_page(); if (!IS_ERR(page)) { @@ -624,6 +629,7 @@ void sgx_free_epc_page(struct sgx_epc_page *page) spin_lock(&node->lock); + page->owner = NULL; list_add_tail(&page->list, &node->free_page_list); sgx_nr_free_pages++; diff --git a/arch/x86/kernel/cpu/sgx/sgx.h b/arch/x86/kernel/cpu/sgx/sgx.h index 4628acec0009..4e1a410b8a62 100644 --- a/arch/x86/kernel/cpu/sgx/sgx.h +++ b/arch/x86/kernel/cpu/sgx/sgx.h @@ -29,7 +29,7 @@ struct sgx_epc_page { unsigned int section; unsigned int flags; - struct sgx_encl_page *owner; + void *owner; struct list_head list; }; -- 2.29.2
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