When handling userspace SREGS writes, check the validity of EFER (i.e.
allowed bits) before writing the new value of EFER through the
per-vendor set_efer callbacks. This prevents userspace from writing
bogus values (e.g. EFER.SVME=1 with nested=0).
Note: on KVM_SET_MSRS, KVM only checks EFER validity in terms of KVM
caps, not guest caps, so it is possible to set EFER bits that are
supported by KVM but not by the guest CPUID. Potentially allowing
userspace to set msrs before CPUID.
However, for KVM_SET_SREGS*, check the validity of the set bits against
both KVM and guest caps. This is consistent with other validity checks
(e.g. for CR4) that check validity against guest caps, which already
imposes the need to set CPUID before SREGS.
Cc: stable@vger.kernel.org
Signed-off-by: Yosry Ahmed <yosry@kernel.org>
Link: https://patch.msgid.link/20260713180153.2728382-2-yosry@kernel.org
Signed-off-by: Sean Christopherson <seanjc@google.com>
At this point, vcpu->arch.ngva_walk and vcpu->arch.root_gva_walk contain
the same information; compare init_kvm_page_walk() on one side with
init_kvm_softmmu() + shadow_mmu_init_context() on the other. They only
differ in when each is active, and root_gva_walk is also used by shadow
paging, via FNAME(walk_addr) and its callers.
Always use the same instance of kvm_pagewalk to do GVA->GPA translations,
for both guest emulation and shadow paging, instead of flipping the
gva_walk pointer back and forth. After all the page walking does behave
the same no matter if you are in guest mode or not; the difference lies
in the behavior of kvm_translate_gpa and thus in vcpu->arch.mmu, not in
the page walker itself.
This completes the transition from walk_mmu/nested_mmu as the page
walking entry points to gva_walk/ngpa_walk, and removes duplicated
code between the initialization of root_mmu.w and ngva_walk (The
Struct Formerly Known As nested_mmu).
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Now that walk_mmu is only accessed for its "w" member, store
directly the pointer to it. Since it is only used to convert
guest GVAs or nGVAs, call it gva_walk.
Note that there is still one container_of() going from (possibly)
walk_mmu.w to its containing struct kvm_mmu, but for now all instances
of struct kvm_pagewalk do live within a kvm_mmu.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
In preparation for separating walking and building of page tables,
introduce a dummy struct kvm_pagewalk and pass it around instead of
its containing kvm_mmu to functions that do not build the page tables.
Outermost functions retrieve the mmu via container_of, while internal
functions can pass around the struct kvm_pagewalk pointer.
x86.c is still mostly oblivious to the existence of struct kvm_pagewalk,
with are only a couple exceptions for now, but the plan is for it to
use struct kvm_pagewalk whenever dealing with guest page tables and have
only limited knowledge of struct kvm_mmu.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Introduce regs.c, and move the vast majority of register specific code out
of x86.c and into regs.c. Deliberately leave behind MSR code, as KVM's MSR
support is complex enough to warrant its own compilation unit, and doesn't
have much in common with the other register code.
Note, "struct kvm_sregs" has fields for EFER and MSR_IA32_APICBASE, and so
the {G,S}ET_REGS flows technically contain a tiny amount of MSR code.
MSR_IA32_APICBASE is already managed by lapic.c, and so doesn't require a
"placement decision". As for EFER, leave all other EFER handling in x86.c
(later to be moved to msrs.c). The primary interface to EFER, set_efer(),
is very much MSR specific, even though EFER is arguably more of a Control
Register than an MSR.
No functional change intended.
Reviewed-by: Kai Huang <kai.huang@intel.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Binbin Wu <binbin.wu@linux.intel.com>
Message-ID: <20260613000329.732085-5-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
