patches/kernel/0020-KVM-x86-emulator-em_sysexit-should-update-ctxt-mode.patch

   1 From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
   2 From: Maxim Levitsky <mlevitsk@redhat.com>
   3 Date: Tue, 21 Jun 2022 18:08:52 +0300
   4 Subject: [PATCH] KVM: x86: emulator: em_sysexit should update ctxt->mode
   5
   6 This is one of the instructions that can change the
   7 processor mode.
   8
   9 Note that this is likely a benign bug, because the only problematic
  10 mode change is from 32 bit to 64 bit which can lead to truncation of RIP,
  11 and it is not possible to do with sysexit,
  12 since sysexit running in 32 bit mode will be limited to 32 bit version.
  13
  14 Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
  15 Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>
  16 ---
  17  arch/x86/kvm/emulate.c | 1 +
  18  1 file changed, 1 insertion(+)
  19
  20 diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
  21 index f8382abe22ff..13181819d52c 100644
  22 --- a/arch/x86/kvm/emulate.c
  23 +++ b/arch/x86/kvm/emulate.c
  24 @@ -2876,6 +2876,7 @@ static int em_sysexit(struct x86_emulate_ctxt *ctxt)
  25         ops->set_segment(ctxt, ss_sel, &ss, 0, VCPU_SREG_SS);
  26
  27         ctxt->_eip = rdx;
  28 +       ctxt->mode = usermode;
  29         *reg_write(ctxt, VCPU_REGS_RSP) = rcx;
  30
  31         return X86EMUL_CONTINUE;