On 04/11/2015 06:46, Kai Huang wrote:
> I found PML was broken since below commit:
>
> commit feda805fe7c4ed9cf78158e73b1218752e3b4314
> Author: Xiao Guangrong <guangrong.x...@linux.intel.com>
> Date: Wed Sep 9 14:05:55 2015 +0800
>
> KVM: VMX: unify SECONDARY_VM_EXEC_CONTROL update
>
> Unify the update in vmx_cpuid_update()
>
> Signed-off-by: Xiao Guangrong <guangrong.x...@linux.intel.com>
> [Rewrite to use vmcs_set_secondary_exec_control. - Paolo]
> Signed-off-by: Paolo Bonzini <pbonz...@redhat.com>
>
> The reason is in above commit vmx_cpuid_update calls
> vmx_secondary_exec_control,
> in which currently SECONDARY_EXEC_ENABLE_PML bit is cleared unconditionally
> (as
> PML is enabled in creating vcpu). Therefore if vcpu_cpuid_update is called
> after
> vcpu is created, PML will be disabled unexpectedly while log-dirty code still
> thinks PML is used.
>
> Fix this by clearing SECONDARY_EXEC_ENABLE_PML in vmx_secondary_exec_control
> only when PML is not supported or not enabled (!enable_pml). This is more
> reasonable as PML is currently either always enabled or disabled. With this
> explicit updating SECONDARY_EXEC_ENABLE_PML in vmx_enable{disable}_pml is not
> needed so also rename vmx_enable{disable}_pml to
> vmx_create{destroy}_pml_buffer.
>
> Signed-off-by: Kai Huang <kai.hu...@linux.intel.com>
>
> ---
>
> v1->v2: Fix this by following Paolo's suggestion. It's better to not to clear
> SECONDARY_EXEC_ENABLE_PML in vmx_secondary_exec_control unconditionally but
> only
> clear it when PML is not supported or enabled.
>
> ---
> arch/x86/kvm/vmx.c | 15 +++++++--------
> 1 file changed, 7 insertions(+), 8 deletions(-)
>
> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
> index 2ac11641..89f4fa2 100644
> --- a/arch/x86/kvm/vmx.c
> +++ b/arch/x86/kvm/vmx.c
> @@ -4718,8 +4718,9 @@ static u32 vmx_secondary_exec_control(struct vcpu_vmx
> *vmx)
> a current VMCS12
> */
> exec_control &= ~SECONDARY_EXEC_SHADOW_VMCS;
> - /* PML is enabled/disabled in creating/destorying vcpu */
> - exec_control &= ~SECONDARY_EXEC_ENABLE_PML;
> +
> + if (!enable_pml)
> + exec_control &= ~SECONDARY_EXEC_ENABLE_PML;
>
> /* Currently, we allow L1 guest to directly run pcommit instruction. */
> exec_control &= ~SECONDARY_EXEC_PCOMMIT;
> @@ -7804,7 +7805,7 @@ static void vmx_get_exit_info(struct kvm_vcpu *vcpu,
> u64 *info1, u64 *info2)
> *info2 = vmcs_read32(VM_EXIT_INTR_INFO);
> }
>
> -static int vmx_enable_pml(struct vcpu_vmx *vmx)
> +static int vmx_create_pml_buffer(struct vcpu_vmx *vmx)
> {
> struct page *pml_pg;
>
> @@ -7817,12 +7818,10 @@ static int vmx_enable_pml(struct vcpu_vmx *vmx)
> vmcs_write64(PML_ADDRESS, page_to_phys(vmx->pml_pg));
> vmcs_write16(GUEST_PML_INDEX, PML_ENTITY_NUM - 1);
>
> - vmcs_set_bits(SECONDARY_VM_EXEC_CONTROL, SECONDARY_EXEC_ENABLE_PML);
> -
> return 0;
> }
>
> -static void vmx_disable_pml(struct vcpu_vmx *vmx)
> +static void vmx_destroy_pml_buffer(struct vcpu_vmx *vmx)
> {
> ASSERT(vmx->pml_pg);
> __free_page(vmx->pml_pg);
> @@ -8706,7 +8705,7 @@ static void vmx_free_vcpu(struct kvm_vcpu *vcpu)
> struct vcpu_vmx *vmx = to_vmx(vcpu);
>
> if (enable_pml)
> - vmx_disable_pml(vmx);
> + vmx_destroy_pml_buffer(vmx);
> free_vpid(vmx->vpid);
> leave_guest_mode(vcpu);
> vmx_load_vmcs01(vcpu);
> @@ -8790,7 +8789,7 @@ static struct kvm_vcpu *vmx_create_vcpu(struct kvm
> *kvm, unsigned int id)
> * for the guest, etc.
> */
> if (enable_pml) {
> - err = vmx_enable_pml(vmx);
> + err = vmx_create_pml_buffer(vmx);
> if (err)
> goto free_vmcs;
> }
>
Applied, thanks!
Paolo
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