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Commit | Line | Data |
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54ebe3cb TL |
1 | From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001 |
2 | From: Maxim Levitsky <mlevitsk@redhat.com> | |
3 | Date: Tue, 21 Jun 2022 18:08:56 +0300 | |
4 | Subject: [PATCH] KVM: x86: emulator: update the emulation mode after CR0 write | |
5 | ||
6 | CR0.PE toggles real/protected mode, thus its update | |
7 | should update the emulation mode. | |
8 | ||
9 | This is likely a benign bug because there is no writeback | |
10 | of state, other than the RIP increment, and when toggling | |
11 | CR0.PE, the CPU has to execute code from a very low memory address. | |
12 | ||
13 | Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com> | |
14 | Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com> | |
15 | --- | |
16 | arch/x86/kvm/emulate.c | 13 ++++++++++++- | |
17 | 1 file changed, 12 insertions(+), 1 deletion(-) | |
18 | ||
19 | diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c | |
20 | index 03a761397599..76c407167449 100644 | |
21 | --- a/arch/x86/kvm/emulate.c | |
22 | +++ b/arch/x86/kvm/emulate.c | |
23 | @@ -3647,11 +3647,22 @@ static int em_movbe(struct x86_emulate_ctxt *ctxt) | |
24 | ||
25 | static int em_cr_write(struct x86_emulate_ctxt *ctxt) | |
26 | { | |
27 | - if (ctxt->ops->set_cr(ctxt, ctxt->modrm_reg, ctxt->src.val)) | |
28 | + int cr_num = ctxt->modrm_reg; | |
29 | + int r; | |
30 | + | |
31 | + if (ctxt->ops->set_cr(ctxt, cr_num, ctxt->src.val)) | |
32 | return emulate_gp(ctxt, 0); | |
33 | ||
34 | /* Disable writeback. */ | |
35 | ctxt->dst.type = OP_NONE; | |
36 | + | |
37 | + if (cr_num == 0) { | |
38 | + /* CR0 write might have updated CR0.PE */ | |
39 | + r = update_emulation_mode(ctxt); | |
40 | + if (r != X86EMUL_CONTINUE) | |
41 | + return r; | |
42 | + } | |
43 | + | |
44 | return X86EMUL_CONTINUE; | |
45 | } | |
46 |