4.19-stable review patch. If anyone has any objections, please let me know.
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From: Sean Christopherson sean.j.christopherson@intel.com
commit 8570f9e881e3fde98801bb3a47eef84dd934d405 upstream.
The address size of an instruction affects the effective address, not the virtual/linear address. The final address may still be truncated, e.g. to 32-bits outside of long mode, but that happens irrespective of the address size, e.g. a 32-bit address size can yield a 64-bit virtual address when using FS/GS with a non-zero base.
Fixes: 064aea774768 ("KVM: nVMX: Decoding memory operands of VMX instructions") Cc: stable@vger.kernel.org Signed-off-by: Sean Christopherson sean.j.christopherson@intel.com Signed-off-by: Paolo Bonzini pbonzini@redhat.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- arch/x86/kvm/vmx.c | 25 +++++++++++++++++++++++-- 1 file changed, 23 insertions(+), 2 deletions(-)
--- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -8193,20 +8193,41 @@ static int get_vmx_mem_address(struct kv if (index_is_valid) off += kvm_register_read(vcpu, index_reg)<<scaling; vmx_get_segment(vcpu, &s, seg_reg); - *ret = s.base + off;
+ /* + * The effective address, i.e. @off, of a memory operand is truncated + * based on the address size of the instruction. Note that this is + * the *effective address*, i.e. the address prior to accounting for + * the segment's base. + */ if (addr_size == 1) /* 32 bit */ - *ret &= 0xffffffff; + off &= 0xffffffff; + else if (addr_size == 0) /* 16 bit */ + off &= 0xffff;
/* Checks for #GP/#SS exceptions. */ exn = false; if (is_long_mode(vcpu)) { + /* + * The virtual/linear address is never truncated in 64-bit + * mode, e.g. a 32-bit address size can yield a 64-bit virtual + * address when using FS/GS with a non-zero base. + */ + *ret = s.base + off; + /* Long mode: #GP(0)/#SS(0) if the memory address is in a * non-canonical form. This is the only check on the memory * destination for long mode! */ exn = is_noncanonical_address(*ret, vcpu); } else if (is_protmode(vcpu)) { + /* + * When not in long mode, the virtual/linear address is + * unconditionally truncated to 32 bits regardless of the + * address size. + */ + *ret = (s.base + off) & 0xffffffff; + /* Protected mode: apply checks for segment validity in the * following order: * - segment type check (#GP(0) may be thrown)