diff options
| author | Sean Christopherson <seanjc@google.com> | 2021-06-09 16:42:22 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2021-07-14 17:06:46 +0200 |
| commit | ffaaf321c09ca0b4c2daf2ae9a810efe958ff196 (patch) | |
| tree | 1644ab74c1711d725873fab9c18428b05897ce4a /arch | |
| parent | 2e5c0d69ec467cf17838be7af30f7fab585412c4 (diff) | |
KVM: nVMX: Ensure 64-bit shift when checking VMFUNC bitmap
[ Upstream commit 0e75225dfa4c5d5d51291f54a3d2d5895bad38da ]
Use BIT_ULL() instead of an open-coded shift to check whether or not a
function is enabled in L1's VMFUNC bitmap. This is a benign bug as KVM
supports only bit 0, and will fail VM-Enter if any other bits are set,
i.e. bits 63:32 are guaranteed to be zero.
Note, "function" is bounded by hardware as VMFUNC will #UD before taking
a VM-Exit if the function is greater than 63.
Before:
if ((vmcs12->vm_function_control & (1 << function)) == 0)
0x000000000001a916 <+118>: mov $0x1,%eax
0x000000000001a91b <+123>: shl %cl,%eax
0x000000000001a91d <+125>: cltq
0x000000000001a91f <+127>: and 0x128(%rbx),%rax
After:
if (!(vmcs12->vm_function_control & BIT_ULL(function & 63)))
0x000000000001a955 <+117>: mov 0x128(%rbx),%rdx
0x000000000001a95c <+124>: bt %rax,%rdx
Fixes: 27c42a1bb867 ("KVM: nVMX: Enable VMFUNC for the L1 hypervisor")
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210609234235.1244004-3-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/x86/kvm/vmx/nested.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c index 1dd092d35cae..ba82b8563b07 100644 --- a/arch/x86/kvm/vmx/nested.c +++ b/arch/x86/kvm/vmx/nested.c @@ -5540,7 +5540,7 @@ static int handle_vmfunc(struct kvm_vcpu *vcpu) } vmcs12 = get_vmcs12(vcpu); - if ((vmcs12->vm_function_control & (1 << function)) == 0) + if (!(vmcs12->vm_function_control & BIT_ULL(function))) goto fail; switch (function) { |