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KVM: when entering real mode align segment base to 16 bytes

PATCH Applied Gleb Natapov 2 participants 2 messages Dec 27, 2010

Subsystems (3)
x86 KVM KVM x86
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Gleb Natapov

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PATCH v2 1/1 KVM: when entering real mode align segment base to 16 bytes

VMX checks that base is equal segment shifted 4 bites left. Otherwise guest entry fails.

Signed-off-by Gleb Natapov <[email protected]>

---

v1->v2
add printk_once.

arch/x86/kvm/vmx.c +3 -1
index 2260783..e1eecf0 100644
@@ -1736,9 +1736,11 @@ static void fix_rmode_seg(int seg, struct kvm_save_segment *save)
 	save->limit = vmcs_read32(sf->limit);
 	save->ar = vmcs_read32(sf->ar_bytes);
 	vmcs_write16(sf->selector, save->base >> 4);
-	vmcs_write32(sf->base, save->base & 0xfffff);
+	vmcs_write32(sf->base, save->base & 0xffff0);
 	vmcs_write32(sf->limit, 0xffff);
 	vmcs_write32(sf->ar_bytes, 0xf3);
+	if (save->base & 0xf)
+		printk_once(KERN_WARNING"kvm: segment base is not 16 bit aligned when entering protected mode (seg=%d)", seg);
 }
 
 static void enter_rmode(struct kvm_vcpu *vcpu)

--
Gleb.

Applied
#1 lore raw
Quoted 3 lines · Gleb Natapov

VMX checks that base is equal segment shifted 4 bites left. Otherwise guest entry fails.

Applied, thanks.

Signature · 1 line
error compiling committee.c: too many arguments to function