Messages in this thread | | | Date | Fri, 10 Dec 2021 17:30:51 +0100 | Subject | Re: [PATCH 18/19] kvm: x86: AMX XCR0 support for guest | From | Paolo Bonzini <> |
| |
On 12/8/21 01:03, Yang Zhong wrote: > + > +#ifdef CONFIG_X86_64 > + if ((xcr0 & XFEATURE_MASK_XTILE) && > + ((xcr0 & XFEATURE_MASK_XTILE) != XFEATURE_MASK_XTILE)) > + return 1; > +#else > + /* > + * Intel AMX instructions can be executed only in 64-bit mode but > + * XSAVE can operate on XTILECFG and XTILEDATA in any mode. > + * Since the FPU core follows SDM recommendation to set > + * XCR[18:17] only in 64-bit environment, here also prevent any > + * guest OS from setting the two bits when host is 32-bit. > + * > + * XFEATURE_MASK_XTILE cannot be used since it is 0 in this case. > + */ > + xcr0 &= ~(XFEATURE_MASK_XTILE_DATA | XFEATURE_MASK_XTILE_CFG); > +#endif
This should not be necessary, because on a 32-bit system the bits won't be part of supported_xcr0.
Paolo
| |