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KVM: Workaround vmx inability to virtualize the reset state

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The reset state has cs.selector == 0xf000 and cs.base == 0xffff0000,
which aren't compatible with vm86 mode, which is used for real mode
virtualization.

When we create a vcpu, we set cs.base to 0xf0000, but if we get there by
way of a reset, the values are inconsistent and vmx refuses to enter
guest mode.

Workaround by detecting the state and munging it appropriately.

Signed-off-by: Avi Kivity <avi@qumranet.com>
This commit is contained in:
Avi Kivity 2007-03-20 18:40:40 +02:00
parent aac012245a
commit 8cb5b03332
1 changed files with 2 additions and 0 deletions
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2
drivers/kvm/vmx.c
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@ -712,6 +712,8 @@ static void enter_rmode(struct kvm_vcpu *vcpu)
vmcs_write32(GUEST_CS_AR_BYTES, 0xf3); vmcs_write32(GUEST_CS_AR_BYTES, 0xf3);
vmcs_write32(GUEST_CS_LIMIT, 0xffff); vmcs_write32(GUEST_CS_LIMIT, 0xffff);
if (vmcs_readl(GUEST_CS_BASE) == 0xffff0000)
vmcs_writel(GUEST_CS_BASE, 0xf0000);
vmcs_write16(GUEST_CS_SELECTOR, vmcs_readl(GUEST_CS_BASE) >> 4); vmcs_write16(GUEST_CS_SELECTOR, vmcs_readl(GUEST_CS_BASE) >> 4);
fix_rmode_seg(VCPU_SREG_ES, &vcpu->rmode.es); fix_rmode_seg(VCPU_SREG_ES, &vcpu->rmode.es);