This is a note to let you know that I've just added the patch titled
KVM: x86: fix RSM into 64-bit protected mode
to the 4.2-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
kvm-x86-fix-rsm-into-64-bit-protected-mode.patch
and it can be found in the queue-4.2 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From b10d92a54dac25a6152f1aa1ffc95c12908035ce Mon Sep 17 00:00:00 2001
From: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Date: Wed, 14 Oct 2015 15:25:52 +0200
Subject: KVM: x86: fix RSM into 64-bit protected mode
From: Paolo Bonzini <pbonzini@xxxxxxxxxx>
commit b10d92a54dac25a6152f1aa1ffc95c12908035ce upstream.
In order to get into 64-bit protected mode, you need to enable
paging while EFER.LMA=1. For this to work, CS.L must be 0.
Currently, we load the segments before CR0 and CR4, which means
that if RSM returns into 64-bit protected mode CS.L is already 1
and everything breaks.
Luckily, CS.L=0 is always the case when executing RSM, because it
is forbidden to execute RSM from 64-bit protected mode. Hence it
is enough to load CR0 and CR4 first, and only then the segments.
Fixes: 660a5d517aaab9187f93854425c4c63f4a09195c
Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/x86/kvm/emulate.c | 10 +++++++---
1 file changed, 7 insertions(+), 3 deletions(-)
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -2418,7 +2418,7 @@ static int rsm_load_state_64(struct x86_
u64 val, cr0, cr4;
u32 base3;
u16 selector;
- int i;
+ int i, r;
for (i = 0; i < 16; i++)
*reg_write(ctxt, i) = GET_SMSTATE(u64, smbase, 0x7ff8 - i * 8);
@@ -2460,13 +2460,17 @@ static int rsm_load_state_64(struct x86_
dt.address = GET_SMSTATE(u64, smbase, 0x7e68);
ctxt->ops->set_gdt(ctxt, &dt);
+ r = rsm_enter_protected_mode(ctxt, cr0, cr4);
+ if (r != X86EMUL_CONTINUE)
+ return r;
+
for (i = 0; i < 6; i++) {
- int r = rsm_load_seg_64(ctxt, smbase, i);
+ r = rsm_load_seg_64(ctxt, smbase, i);
if (r != X86EMUL_CONTINUE)
return r;
}
- return rsm_enter_protected_mode(ctxt, cr0, cr4);
+ return X86EMUL_CONTINUE;
}
static int em_rsm(struct x86_emulate_ctxt *ctxt)
Patches currently in stable-queue which might be from pbonzini@xxxxxxxxxx are
queue-4.2/kvm-x86-fix-smi-to-halted-vcpu.patch
queue-4.2/kvm-x86-clean-up-kvm_arch_vcpu_runnable.patch
queue-4.2/kvm-x86-fix-rsm-into-64-bit-protected-mode.patch
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