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SubjectRe: [PATCH v5 7/8] KVM: VMX: Update PID-pointer table entry when APIC ID is changed
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On 12/31/21 8:28 AM, Zeng Guang wrote:
> In xAPIC mode, guest is allowed to modify APIC ID at runtime.
> If IPI virtualization is enabled, corresponding entry in
> PID-pointer table need change accordingly.
>
> Signed-off-by: Zeng Guang <guang.zeng@intel.com>
> ---
> arch/x86/include/asm/kvm_host.h | 1 +
> arch/x86/kvm/lapic.c | 7 +++++--
> arch/x86/kvm/vmx/vmx.c | 12 ++++++++++++
> 3 files changed, 18 insertions(+), 2 deletions(-)
>
> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> index 2164b9f4c7b0..753bf2a7cebc 100644
> --- a/arch/x86/include/asm/kvm_host.h
> +++ b/arch/x86/include/asm/kvm_host.h
> @@ -1493,6 +1493,7 @@ struct kvm_x86_ops {
> int (*complete_emulated_msr)(struct kvm_vcpu *vcpu, int err);
>
> void (*vcpu_deliver_sipi_vector)(struct kvm_vcpu *vcpu, u8 vector);
> + void (*update_ipiv_pid_entry)(struct kvm_vcpu *vcpu, u8 old_id, u8 new_id);
> };
>
> struct kvm_x86_nested_ops {
> diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
> index 3ce7142ba00e..83c2c7594bcd 100644
> --- a/arch/x86/kvm/lapic.c
> +++ b/arch/x86/kvm/lapic.c
> @@ -2007,9 +2007,12 @@ int kvm_lapic_reg_write(struct kvm_lapic *apic, u32 reg, u32 val)
>
> switch (reg) {
> case APIC_ID: /* Local APIC ID */
> - if (!apic_x2apic_mode(apic))
> + if (!apic_x2apic_mode(apic)) {
> + u8 old_id = kvm_lapic_get_reg(apic, APIC_ID) >> 24;
> +
> kvm_apic_set_xapic_id(apic, val >> 24);
> - else
> + kvm_x86_ops.update_ipiv_pid_entry(apic->vcpu, old_id, val >> 24);

Won't this blow up on AMD since there is no corresponding SVM op?

Thanks,
Tom

> + } else
> ret = 1;
> break;
>
> diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
> index 2e65464d6dee..f21ce15c5eb8 100644
> --- a/arch/x86/kvm/vmx/vmx.c
> +++ b/arch/x86/kvm/vmx/vmx.c
> @@ -7633,6 +7633,17 @@ static void vmx_vm_destroy(struct kvm *kvm)
> free_pages((unsigned long)kvm_vmx->pid_table, MAX_PID_TABLE_ORDER);
> }
>
> +static void vmx_update_ipiv_pid_entry(struct kvm_vcpu *vcpu, u8 old_id, u8 new_id)
> +{
> + if (enable_ipiv && kvm_vcpu_apicv_active(vcpu)) {
> + u64 *pid_table = to_kvm_vmx(vcpu->kvm)->pid_table;
> +
> + WRITE_ONCE(pid_table[old_id], 0);
> + WRITE_ONCE(pid_table[new_id], __pa(&to_vmx(vcpu)->pi_desc) |
> + PID_TABLE_ENTRY_VALID);
> + }
> +}
> +
> static struct kvm_x86_ops vmx_x86_ops __initdata = {
> .name = "kvm_intel",
>
> @@ -7770,6 +7781,7 @@ static struct kvm_x86_ops vmx_x86_ops __initdata = {
> .complete_emulated_msr = kvm_complete_insn_gp,
>
> .vcpu_deliver_sipi_vector = kvm_vcpu_deliver_sipi_vector,
> + .update_ipiv_pid_entry = vmx_update_ipiv_pid_entry,
> };
>
> static __init void vmx_setup_user_return_msrs(void)
>

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