[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-changelog] [xen staging] x86: don't allow clearing of TF_kernel_mode for other than 64-bit PV
commit c5985168152c7d990a9deb03193e66cbcc7281d9 Author: Jan Beulich <jbeulich@xxxxxxxx> AuthorDate: Fri Apr 5 15:40:42 2019 +0200 Commit: Jan Beulich <jbeulich@xxxxxxxx> CommitDate: Fri Apr 5 15:40:42 2019 +0200 x86: don't allow clearing of TF_kernel_mode for other than 64-bit PV The flag is really only meant for those, both HVM and 32-bit PV tell kernel from user mode based on CPL/RPL. Remove the all-question-marks comment and let's be on the safe side here and also suppress clearing for 32-bit PV (this isn't a fast path after all). Remove no longer necessary is_pv_32bit_*() from sh_update_cr3() and sh_walk_guest_tables(). Note that shadow_one_bit_disable() already assumes the new behavior. Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx> Reviewed-by: Wei Liu <wei.liu2@xxxxxxxxxx> Acked-by: George Dunlap <george.dunlap@xxxxxxxxxx> Acked-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx> --- xen/arch/x86/domain.c | 12 +++++++++--- xen/arch/x86/mm/shadow/multi.c | 4 ++-- 2 files changed, 11 insertions(+), 5 deletions(-) diff --git a/xen/arch/x86/domain.c b/xen/arch/x86/domain.c index ebd9e85132..873b510c3f 100644 --- a/xen/arch/x86/domain.c +++ b/xen/arch/x86/domain.c @@ -843,9 +843,15 @@ int arch_set_info_guest( return -EINVAL; } - v->arch.flags &= ~TF_kernel_mode; - if ( (flags & VGCF_in_kernel) || is_hvm_domain(d)/*???*/ ) - v->arch.flags |= TF_kernel_mode; + v->arch.flags |= TF_kernel_mode; + if ( unlikely(!(flags & VGCF_in_kernel)) && + /* + * TF_kernel_mode is only allowed to be clear for 64-bit PV. See + * update_cr3(), sh_update_cr3(), sh_walk_guest_tables(), and + * shadow_one_bit_disable() for why that is. + */ + !is_hvm_domain(d) && !is_pv_32bit_domain(d) ) + v->arch.flags &= ~TF_kernel_mode; v->arch.vgc_flags = flags; diff --git a/xen/arch/x86/mm/shadow/multi.c b/xen/arch/x86/mm/shadow/multi.c index 953c0344aa..1d282c928f 100644 --- a/xen/arch/x86/mm/shadow/multi.c +++ b/xen/arch/x86/mm/shadow/multi.c @@ -180,7 +180,7 @@ sh_walk_guest_tables(struct vcpu *v, unsigned long va, walk_t *gw, INVALID_MFN, v->arch.paging.shadow.gl3e); #else /* 32 or 64 */ const struct domain *d = v->domain; - mfn_t root_mfn = ((v->arch.flags & TF_kernel_mode) || is_pv_32bit_domain(d) + mfn_t root_mfn = (v->arch.flags & TF_kernel_mode ? pagetable_get_mfn(v->arch.guest_table) : pagetable_get_mfn(v->arch.guest_table_user)); void *root_map = map_domain_page(root_mfn); @@ -3976,7 +3976,7 @@ sh_update_cr3(struct vcpu *v, int do_locking, bool noflush) v, (unsigned long)pagetable_get_pfn(v->arch.guest_table)); #if GUEST_PAGING_LEVELS == 4 - if ( !(v->arch.flags & TF_kernel_mode) && !is_pv_32bit_domain(d) ) + if ( !(v->arch.flags & TF_kernel_mode) ) gmfn = pagetable_get_mfn(v->arch.guest_table_user); else #endif -- generated by git-patchbot for /home/xen/git/xen.git#staging _______________________________________________ Xen-changelog mailing list Xen-changelog@xxxxxxxxxxxxxxxxxxxx https://lists.xenproject.org/xen-changelog
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