47 lines
1.4 KiB
Diff
47 lines
1.4 KiB
Diff
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From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
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From: Maxim Levitsky <mlevitsk@redhat.com>
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Date: Tue, 21 Jun 2022 18:08:56 +0300
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Subject: [PATCH] KVM: x86: emulator: update the emulation mode after CR0 write
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CR0.PE toggles real/protected mode, thus its update
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should update the emulation mode.
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This is likely a benign bug because there is no writeback
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of state, other than the RIP increment, and when toggling
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CR0.PE, the CPU has to execute code from a very low memory address.
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Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
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Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>
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---
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arch/x86/kvm/emulate.c | 13 ++++++++++++-
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1 file changed, 12 insertions(+), 1 deletion(-)
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diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
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index c582639ea2b4..38d9bfa650ec 100644
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--- a/arch/x86/kvm/emulate.c
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+++ b/arch/x86/kvm/emulate.c
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@@ -3636,11 +3636,22 @@ static int em_movbe(struct x86_emulate_ctxt *ctxt)
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static int em_cr_write(struct x86_emulate_ctxt *ctxt)
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{
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- if (ctxt->ops->set_cr(ctxt, ctxt->modrm_reg, ctxt->src.val))
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+ int cr_num = ctxt->modrm_reg;
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+ int r;
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+
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+ if (ctxt->ops->set_cr(ctxt, cr_num, ctxt->src.val))
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return emulate_gp(ctxt, 0);
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/* Disable writeback. */
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ctxt->dst.type = OP_NONE;
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+
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+ if (cr_num == 0) {
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+ /* CR0 write might have updated CR0.PE */
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+ r = update_emulation_mode(ctxt);
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+ if (r != X86EMUL_CONTINUE)
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+ return r;
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+ }
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+
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return X86EMUL_CONTINUE;
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}
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