For example migration between Westmere and Nehelem hosts.
The patch fixes the guest segments similar to enter_rmode function.
Signed-off-by: Orit Wasserman <owasserm@xxxxxxxxxx>
---
arch/x86/kvm/vmx.c | 38 ++++++++++++++++++++++++++++++++++++++
1 files changed, 38 insertions(+), 0 deletions(-)
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 32eb588..2eca18f 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -3229,6 +3229,44 @@ static void vmx_set_segment(struct kvm_vcpu *vcpu,
vmcs_write32(sf->ar_bytes, ar);
__clear_bit(VCPU_EXREG_CPL, (ulong *)&vcpu->arch.regs_avail);
+
+ /*
+ * Fix segments for real mode guest in hosts that don't have
+ * "unrestricted_mode" or it was disabled.
+ * This is done to allow migration of the guests from hosts with
+ * unrestricted guest like Westmere to older host that don't have
+ * unrestricted guest like Nehelem.
+ */
+ if (!enable_unrestricted_guest && vmx->rmode.vm86_active) {
+ switch (seg) {
+ case VCPU_SREG_CS:
+ vmcs_write32(GUEST_CS_AR_BYTES, 0xf3);
+ 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);
+ break;
+ case VCPU_SREG_ES:
+ fix_rmode_seg(VCPU_SREG_ES, &vmx->rmode.es);
+ break;
+ case VCPU_SREG_DS:
+ fix_rmode_seg(VCPU_SREG_DS, &vmx->rmode.ds);
+ break;
+ case VCPU_SREG_GS:
+ fix_rmode_seg(VCPU_SREG_GS, &vmx->rmode.gs);
+ break;
+ case VCPU_SREG_FS:
+ fix_rmode_seg(VCPU_SREG_FS, &vmx->rmode.fs);
+ break;
+ case VCPU_SREG_SS:
+ vmcs_write16(GUEST_SS_SELECTOR,
+ vmcs_readl(GUEST_SS_BASE) >> 4);
+ vmcs_write32(GUEST_SS_LIMIT, 0xffff);
+ vmcs_write32(GUEST_SS_AR_BYTES, 0xf3);
+ break;
+ }
+ }
}
static void vmx_get_cs_db_l_bits(struct kvm_vcpu *vcpu, int *db, int *l)
--
1.7.7.6
--
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