[PATCH AUTOSEL for 4.9 031/100] kvm: vmx: Flush TLB when the APIC-access address changes

From: alexander . levin
Date: Tue Dec 12 2017 - 20:58:26 EST


From: Jim Mattson <jmattson@xxxxxxxxxx>

[ Upstream commit fb6c8198431311027c3434d4e94ab8bc040f7aea ]

Quoting from the Intel SDM, volume 3, section 28.3.3.4: Guidelines for
Use of the INVEPT Instruction:

If EPT was in use on a logical processor at one time with EPTP X, it
is recommended that software use the INVEPT instruction with the
"single-context" INVEPT type and with EPTP X in the INVEPT descriptor
before a VM entry on the same logical processor that enables EPT with
EPTP X and either (a) the "virtualize APIC accesses" VM-execution
control was changed from 0 to 1; or (b) the value of the APIC-access
address was changed.

In the nested case, the burden falls on L1, unless L0 enables EPT in
vmcs02 when L1 doesn't enable EPT in vmcs12.

Signed-off-by: Jim Mattson <jmattson@xxxxxxxxxx>
Signed-off-by: Radim KrÄmÃÅ <rkrcmar@xxxxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxx>
---
arch/x86/kvm/vmx.c | 18 +++++++++++++++++-
1 file changed, 17 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index f0d3de153e29..3ec670af9cae 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -3816,6 +3816,12 @@ static void vmx_flush_tlb(struct kvm_vcpu *vcpu)
__vmx_flush_tlb(vcpu, to_vmx(vcpu)->vpid);
}

+static void vmx_flush_tlb_ept_only(struct kvm_vcpu *vcpu)
+{
+ if (enable_ept)
+ vmx_flush_tlb(vcpu);
+}
+
static void vmx_decache_cr0_guest_bits(struct kvm_vcpu *vcpu)
{
ulong cr0_guest_owned_bits = vcpu->arch.cr0_guest_owned_bits;
@@ -8513,6 +8519,7 @@ static void vmx_set_virtual_x2apic_mode(struct kvm_vcpu *vcpu, bool set)
} else {
sec_exec_control &= ~SECONDARY_EXEC_VIRTUALIZE_X2APIC_MODE;
sec_exec_control |= SECONDARY_EXEC_VIRTUALIZE_APIC_ACCESSES;
+ vmx_flush_tlb_ept_only(vcpu);
}
vmcs_write32(SECONDARY_VM_EXEC_CONTROL, sec_exec_control);

@@ -8538,8 +8545,10 @@ static void vmx_set_apic_access_page_addr(struct kvm_vcpu *vcpu, hpa_t hpa)
*/
if (!is_guest_mode(vcpu) ||
!nested_cpu_has2(get_vmcs12(&vmx->vcpu),
- SECONDARY_EXEC_VIRTUALIZE_APIC_ACCESSES))
+ SECONDARY_EXEC_VIRTUALIZE_APIC_ACCESSES)) {
vmcs_write64(APIC_ACCESS_ADDR, hpa);
+ vmx_flush_tlb_ept_only(vcpu);
+ }
}

static void vmx_hwapic_isr_update(struct kvm_vcpu *vcpu, int max_isr)
@@ -10114,6 +10123,9 @@ static void prepare_vmcs02(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12)
if (nested_cpu_has_ept(vmcs12)) {
kvm_mmu_unload(vcpu);
nested_ept_init_mmu_context(vcpu);
+ } else if (nested_cpu_has2(vmcs12,
+ SECONDARY_EXEC_VIRTUALIZE_APIC_ACCESSES)) {
+ vmx_flush_tlb_ept_only(vcpu);
}

if (vmcs12->vm_entry_controls & VM_ENTRY_LOAD_IA32_EFER)
@@ -10854,6 +10866,10 @@ static void nested_vmx_vmexit(struct kvm_vcpu *vcpu, u32 exit_reason,
vmx->nested.change_vmcs01_virtual_x2apic_mode = false;
vmx_set_virtual_x2apic_mode(vcpu,
vcpu->arch.apic_base & X2APIC_ENABLE);
+ } else if (!nested_cpu_has_ept(vmcs12) &&
+ nested_cpu_has2(vmcs12,
+ SECONDARY_EXEC_VIRTUALIZE_APIC_ACCESSES)) {
+ vmx_flush_tlb_ept_only(vcpu);
}

/* This is needed for same reason as it was needed in prepare_vmcs02 */
--
2.11.0