|author||Linus Torvalds <email@example.com>||2015-05-21 20:15:16 -0700|
|committer||Linus Torvalds <firstname.lastname@example.org>||2015-05-21 20:15:16 -0700|
Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm
Pull KVM fixes from Paolo Bonzini: "This includes a fix for two oopses, one on PPC and on x86. The rest is fixes for bugs with newer Intel processors" * tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: kvm/fpu: Enable eager restore kvm FPU for MPX Revert "KVM: x86: drop fpu_activate hook" kvm: fix crash in kvm_vcpu_reload_apic_access_page KVM: MMU: fix SMAP virtualization KVM: MMU: fix CR4.SMEP=1, CR0.WP=0 with shadow pages KVM: MMU: fix smap permission check KVM: PPC: Book3S HV: Fix list traversal in error case
Diffstat (limited to 'Documentation')
1 files changed, 14 insertions, 4 deletions
diff --git a/Documentation/virtual/kvm/mmu.txt b/Documentation/virtual/kvm/mmu.txt
index 53838d9c6295..c59bd9bc41ef 100644
@@ -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).
+ 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).
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