| Message ID | 1431356122-8500-2-git-send-email-guangrong.xiao@linux.intel.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 11/05/2015 16:55, Xiao Guangrong wrote: > Document this new role field > > Signed-off-by: Xiao Guangrong <guangrong.xiao@linux.intel.com> > --- > Documentation/virtual/kvm/mmu.txt | 18 ++++++++++++++---- > 1 file changed, 14 insertions(+), 4 deletions(-) > > diff --git a/Documentation/virtual/kvm/mmu.txt b/Documentation/virtual/kvm/mmu.txt > index 53838d9..c59bd9b 100644 > --- a/Documentation/virtual/kvm/mmu.txt > +++ b/Documentation/virtual/kvm/mmu.txt > @@ -169,6 +169,10 @@ Shadow pages contain the following information: > Contains the value of cr4.smep && !cr0.wp for which the page is valid > (pages for which this is true are different from other pages; see the > treatment of cr0.wp=0 below). > + role.smap_andnot_wp: > + Contains the value of cr4.smap && !cr0.wp for which the page is valid > + (pages for which this is true are different from other pages; see the > + treatment of cr0.wp=0 below). > gfn: > Either the guest page table containing the translations shadowed by this > page, or the base page frame for linear translations. See role.direct. > @@ -344,10 +348,16 @@ on fault type: > > (user write faults generate a #PF) > > -In the first case there is an additional complication if CR4.SMEP is > -enabled: since we've turned the page into a kernel page, the kernel may now > -execute it. We handle this by also setting spte.nx. If we get a user > -fetch or read fault, we'll change spte.u=1 and spte.nx=gpte.nx back. > +In the first case there are two additional complications: > +- if CR4.SMEP is enabled: since we've turned the page into a kernel page, > + the kernel may now execute it. We handle this by also setting spte.nx. > + If we get a user fetch or read fault, we'll change spte.u=1 and > + spte.nx=gpte.nx back. > +- if CR4.SMAP is disabled: since the page has been changed to a kernel > + page, it can not be reused when CR4.SMAP is enabled. We set > + CR4.SMAP && !CR0.WP into shadow page's role to avoid this case. Note, > + here we do not care the case that CR4.SMAP is enabled since KVM will > + directly inject #PF to guest due to failed permission check. > > To prevent an spte that was converted into a kernel page with cr0.wp=0 > from being written by the kernel after cr0.wp has changed to 1, we make > Thanks, squashed with 1/2 and both applied. Paolo -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/Documentation/virtual/kvm/mmu.txt b/Documentation/virtual/kvm/mmu.txt index 53838d9..c59bd9b 100644 --- a/Documentation/virtual/kvm/mmu.txt +++ b/Documentation/virtual/kvm/mmu.txt @@ -169,6 +169,10 @@ Shadow pages contain the following information: Contains the value of cr4.smep && !cr0.wp for which the page is valid (pages for which this is true are different from other pages; see the treatment of cr0.wp=0 below). + role.smap_andnot_wp: + Contains the value of cr4.smap && !cr0.wp for which the page is valid + (pages for which this is true are different from other pages; see the + treatment of cr0.wp=0 below). gfn: Either the guest page table containing the translations shadowed by this page, or the base page frame for linear translations. See role.direct. @@ -344,10 +348,16 @@ on fault type: (user write faults generate a #PF) -In the first case there is an additional complication if CR4.SMEP is -enabled: since we've turned the page into a kernel page, the kernel may now -execute it. We handle this by also setting spte.nx. If we get a user -fetch or read fault, we'll change spte.u=1 and spte.nx=gpte.nx back. +In the first case there are two additional complications: +- if CR4.SMEP is enabled: since we've turned the page into a kernel page, + the kernel may now execute it. We handle this by also setting spte.nx. + If we get a user fetch or read fault, we'll change spte.u=1 and + spte.nx=gpte.nx back. +- if CR4.SMAP is disabled: since the page has been changed to a kernel + page, it can not be reused when CR4.SMAP is enabled. We set + CR4.SMAP && !CR0.WP into shadow page's role to avoid this case. Note, + here we do not care the case that CR4.SMAP is enabled since KVM will + directly inject #PF to guest due to failed permission check. To prevent an spte that was converted into a kernel page with cr0.wp=0 from being written by the kernel after cr0.wp has changed to 1, we make
Document this new role field Signed-off-by: Xiao Guangrong <guangrong.xiao@linux.intel.com> --- Documentation/virtual/kvm/mmu.txt | 18 ++++++++++++++---- 1 file changed, 14 insertions(+), 4 deletions(-)