[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH 07/10] x86/hvm: pkeys, add functions to support PKRU access/write
On 16/11/15 10:31, Huaitong Han wrote: > This patch adds functions to support PKRU access/write > > Signed-off-by: Huaitong Han <huaitong.han@xxxxxxxxx> > > diff --git a/xen/include/asm-x86/processor.h b/xen/include/asm-x86/processor.h > index f507f5e..427eb84 100644 > --- a/xen/include/asm-x86/processor.h > +++ b/xen/include/asm-x86/processor.h > @@ -336,6 +336,44 @@ static inline void write_cr4(unsigned long val) > asm volatile ( "mov %0,%%cr4" : : "r" (val) ); > } > > +static inline unsigned int read_pkru(void) > +{ > + unsigned int eax, edx; > + unsigned int ecx = 0; > + unsigned int pkru; > + > + asm volatile(".byte 0x0f,0x01,0xee\n\t" > + : "=a" (eax), "=d" (edx) > + : "c" (ecx)); > + pkru = eax; > + return pkru; This can be far more simple. { unsigned int pkru; asm volatile (".byte 0x0f,0x01,0xee" : "=a" (pkru) : "c" (0) : "dx"); return pkru; } > +} > + > +static inline void write_pkru(unsigned int pkru) > +{ > + unsigned int eax = pkru; > + unsigned int ecx = 0; > + unsigned int edx = 0; > + > + asm volatile(".byte 0x0f,0x01,0xef\n\t" > + : : "a" (eax), "c" (ecx), "d" (edx)); > +} I don't see any need for Xen to use WRPKRU, and this helper isn't used anywhere in your series. Please drop it (unless I have overlooked something). > + > +/* macros for pkru */ > +#define PKRU_READ 0 > +#define PKRU_WRITE 1 > +#define PKRU_ATTRS 2 > + > +/* > +* PKRU defines 32 bits, there are 16 domains and 2 attribute bits per > +* domain in pkru, pkeys is index to a defined domain, so the value of > +* pte_pkeys * PKRU_ATTRS + R/W is offset of a defined domain attribute. > +*/ > +#define READ_PKRU_AD(x) ((read_pkru() >> (x * PKRU_ATTRS + PKRU_READ)) & 1) > +#define READ_PKRU_WD(x) ((read_pkru() >> (x * PKRU_ATTRS + PKRU_WRITE)) & 1) Sorry, but no. This hides expensive rdpkru instructions in innocuous code. Instead, a function manipulating the keys should cache rdpkru once, and use the following helpers: static inline bool_t pkru_ad(unsigned int pkru, unsigned int key); static inline bool_t pkru_wd(unsigned int pkru, unsigned int key); ~Andrew _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
|
Lists.xenproject.org is hosted with RackSpace, monitoring our |