[patch 1/3] KVM: task switch: segment base is linear address

Marcelo Tosatti
2008-07-16T22:18:34Z

[-- Attachment #1: task-switch-linear --]
[-- Type: text/plain, Size: 1810 bytes --]

The segment base is always a linear address, so translate before
accessing guest memory.

Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

Index: kvm/arch/x86/kvm/x86.c
===================================================================
--- kvm.orig/arch/x86/kvm/x86.c
+++ kvm/arch/x86/kvm/x86.c
@@ -3234,6 +3234,7 @@ static void get_segment_descritptor_dtab
static int load_guest_segment_descriptor(struct kvm_vcpu *vcpu, u16 selector,
struct desc_struct *seg_desc)
{
+ gpa_t gpa;
struct descriptor_table dtable;
u16 index = selector >> 3;

@@ -3243,13 +3244,16 @@ static int load_guest_segment_descriptor
kvm_queue_exception_e(vcpu, GP_VECTOR, selector & 0xfffc);
return 1;
}
- return kvm_read_guest(vcpu->kvm, dtable.base + index * 8, seg_desc, 8);
+ gpa = vcpu->arch.mmu.gva_to_gpa(vcpu, dtable.base);
+ gpa += index * 8;
+ return kvm_read_guest(vcpu->kvm, gpa, seg_desc, 8);
}

/* allowed just for 8 bytes segments */
static int save_guest_segment_descriptor(struct kvm_vcpu *vcpu, u16 selector,
struct desc_struct *seg_desc)
{
+ gpa_t gpa;
struct descriptor_table dtable;
u16 index = selector >> 3;

@@ -3257,7 +3261,9 @@ static int save_guest_segment_descriptor

if (dtable.limit < index * 8 + 7)
return 1;
- return kvm_write_guest(vcpu->kvm, dtable.base + index * 8, seg_desc, 8);
+ gpa = vcpu->arch.mmu.gva_to_gpa(vcpu, dtable.base);
+ gpa += index * 8;
+ return kvm_write_guest(vcpu->kvm, gpa, seg_desc, 8);
}

static u32 get_tss_base_addr(struct kvm_vcpu *vcpu,
@@ -3269,7 +3275,7 @@ static u32 get_tss_base_addr(struct kvm_
base_addr |= (seg_desc->base1 << 16);
base_addr |= (seg_desc->base2 << 24);

- return base_addr;
+ return vcpu->arch.mmu.gva_to_gpa(vcpu, base_addr);
}

static int load_tss_segment32(struct kvm_vcpu *vcpu,

--