[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [PATCH v6] x86/dom0: disable SMAP for PV domain building only
On Wed, Aug 28, 2024 at 12:51:23PM +0100, Andrew Cooper wrote: > On 28/08/2024 12:50 pm, Jan Beulich wrote: > > On 28.08.2024 13:30, Roger Pau Monne wrote: > >> Move the logic that disables SMAP so it's only performed when building a PV > >> dom0, PVH dom0 builder doesn't require disabling SMAP. > >> > >> The fixes tag is to account for the wrong usage of cpu_has_smap in > >> create_dom0(), it should instead have used > >> boot_cpu_has(X86_FEATURE_XEN_SMAP). Fix while moving the logic to apply > >> to PV > >> only. > >> > >> While there also make cr4_pv32_mask __ro_after_init. > >> > >> Fixes: 493ab190e5b1 ('xen/sm{e, a}p: allow disabling sm{e, a}p for Xen > >> itself') > >> Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx> > > Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx> > > preferably with ... > > > >> @@ -1051,6 +1051,34 @@ out: > >> return rc; > >> } > >> > >> +int __init dom0_construct_pv(struct domain *d, > >> + const module_t *image, > >> + unsigned long image_headroom, > >> + module_t *initrd, > >> + const char *cmdline) > >> +{ > >> + int rc; > >> + > >> + /* > >> + * Temporarily clear SMAP in CR4 to allow user-accesses in > >> + * construct_dom0(). This saves a large number of corner cases > > ... the final 's' dropped here and ... > > > >> + * interactions with copy_from_user(). > >> + */ > >> + if ( boot_cpu_has(X86_FEATURE_XEN_SMAP) ) > >> + { > >> + cr4_pv32_mask &= ~X86_CR4_SMAP; > >> + write_cr4(read_cr4() & ~X86_CR4_SMAP); > >> + } > >> + rc = dom0_construct(d, image, image_headroom, initrd, cmdline); > >> + if ( boot_cpu_has(X86_FEATURE_XEN_SMAP) ) > > ... blank lines added around the function call. Happy to adjust while > > committing, so long as you agree. > > +1 to both suggestions. Sure, please adjust at commit. > Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx> Thanks (to both).
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