Messages in this thread |  | | From | "Sakkinen, Jarkko" <> | Subject | Re: [PATCH v2 1/6] x86/sgx: Provide indication of life-cycle of EPC pages | Date | Tue, 27 Jul 2021 02:04:21 +0000 |
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On Mon, 2021-07-19 at 11:20 -0700, Tony Luck wrote: > 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);
I would instead set owner to epc_page inside sgx_alloc_epc_page(), when NULL is passed to owner. That would be semantically sound.
/Jarkko
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