2018-05-10 4:56 GMT+08:00 Krish Sadhukhan <krish.sadhukhan@xxxxxxxxxx>:
> From: Jim Mattson <jmattson@xxxxxxxxxx>
>
> The local APIC can be in one of three modes: disabled, xAPIC or
> x2APIC. (A fourth mode, "invalid," is included for completeness.)
>
> Using the new enumeration can make some of the APIC mode logic easier
> to read. In kvm_set_apic_base, for instance, it is clear that one
> cannot transition directly from x2APIC mode to xAPIC mode or directly
> from APIC disabled to x2APIC mode.
>
> Signed-off-by: Jim Mattson <jmattson@xxxxxxxxxx>
> Signed-off-by: Krish Sadhukhan <krish.sadhukhan@xxxxxxxxxx>
> ---
> arch/x86/kvm/lapic.h | 14 ++++++++++++++
> arch/x86/kvm/x86.c | 31 +++++++++++++++++++------------
> 2 files changed, 33 insertions(+), 12 deletions(-)
>
> diff --git a/arch/x86/kvm/lapic.h b/arch/x86/kvm/lapic.h
> index edce055..ed0ed39 100644
> --- a/arch/x86/kvm/lapic.h
> +++ b/arch/x86/kvm/lapic.h
> @@ -16,6 +16,13 @@
> #define APIC_BUS_CYCLE_NS 1
> #define APIC_BUS_FREQUENCY (1000000000ULL / APIC_BUS_CYCLE_NS)
>
> +enum lapic_mode {
> + LAPIC_MODE_DISABLED = 0,
> + LAPIC_MODE_INVALID = X2APIC_ENABLE,
> + LAPIC_MODE_XAPIC = MSR_IA32_APICBASE_ENABLE,
> + LAPIC_MODE_X2APIC = MSR_IA32_APICBASE_ENABLE | X2APIC_ENABLE,
> +};
> +
> struct kvm_timer {
> struct hrtimer timer;
> s64 period; /* unit: ns */
> @@ -89,6 +96,7 @@ u64 kvm_get_apic_base(struct kvm_vcpu *vcpu);
> int kvm_set_apic_base(struct kvm_vcpu *vcpu, struct msr_data *msr_info);
> int kvm_apic_get_state(struct kvm_vcpu *vcpu, struct kvm_lapic_state *s);
> int kvm_apic_set_state(struct kvm_vcpu *vcpu, struct kvm_lapic_state *s);
> +enum lapic_mode kvm_get_apic_mode(struct kvm_vcpu *vcpu);
> int kvm_lapic_find_highest_irr(struct kvm_vcpu *vcpu);
>
> u64 kvm_get_lapic_tscdeadline_msr(struct kvm_vcpu *vcpu);
> @@ -220,4 +228,10 @@ void kvm_lapic_switch_to_hv_timer(struct kvm_vcpu *vcpu);
> void kvm_lapic_expired_hv_timer(struct kvm_vcpu *vcpu);
> bool kvm_lapic_hv_timer_in_use(struct kvm_vcpu *vcpu);
> void kvm_lapic_restart_hv_timer(struct kvm_vcpu *vcpu);
> +
> +static inline enum lapic_mode kvm_apic_mode(u64 apic_base)
> +{
> + return apic_base & (MSR_IA32_APICBASE_ENABLE | X2APIC_ENABLE);
> +}
> +
> #endif
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 51ecd38..5f5874c 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -318,23 +318,30 @@ u64 kvm_get_apic_base(struct kvm_vcpu *vcpu)
> }
> EXPORT_SYMBOL_GPL(kvm_get_apic_base);
>
> +enum lapic_mode kvm_get_apic_mode(struct kvm_vcpu *vcpu)
> +{
> + return kvm_apic_mode(kvm_get_apic_base(vcpu));
> +}
> +EXPORT_SYMBOL_GPL(kvm_get_apic_mode);
> +
> int kvm_set_apic_base(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
> {
> - u64 old_state = vcpu->arch.apic_base &
> - (MSR_IA32_APICBASE_ENABLE | X2APIC_ENABLE);
> - u64 new_state = msr_info->data &
> - (MSR_IA32_APICBASE_ENABLE | X2APIC_ENABLE);
> + enum lapic_mode old_mode = kvm_get_apic_mode(vcpu);
> + enum lapic_mode new_mode = kvm_apic_mode(msr_info->data);
> u64 reserved_bits = ((~0ULL) << cpuid_maxphyaddr(vcpu)) | 0x2ff |
> (guest_cpuid_has(vcpu, X86_FEATURE_X2APIC) ? 0 : X2APIC_ENABLE);
>
> - if ((msr_info->data & reserved_bits) || new_state == X2APIC_ENABLE)
> - return 1;
> - if (!msr_info->host_initiated &&
> - ((new_state == MSR_IA32_APICBASE_ENABLE &&
> - old_state == (MSR_IA32_APICBASE_ENABLE | X2APIC_ENABLE)) ||
> - (new_state == (MSR_IA32_APICBASE_ENABLE | X2APIC_ENABLE) &&
> - old_state == 0)))
> - return 1;
> + if (!msr_info->host_initiated) {
> + if ((msr_info->data & reserved_bits) != 0 ||
> + new_mode == LAPIC_MODE_INVALID)
> + return 1;
This is opposite to commit d3802286fa (kvm: x86: Disallow illegal
IA32_APIC_BASE MSR values), any good reason this time?
Regards,
Wanpeng Li
> + if (old_mode == LAPIC_MODE_X2APIC &&
> + new_mode == LAPIC_MODE_XAPIC)
> + return 1;
> + if (old_mode == LAPIC_MODE_DISABLED &&
> + new_mode == LAPIC_MODE_X2APIC)
> + return 1;
> + }
>
> kvm_lapic_set_base(vcpu, msr_info->data);
> return 0;
> --
> 2.9.5
>
