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Date: Tue, 17 May 2016 14:09:44 +0200
From: Paolo Bonzini <pbonzini@...hat.com>
To: Suravee Suthikulpanit <Suravee.Suthikulpanit@....com>,
rkrcmar@...hat.com, joro@...tes.org, bp@...en8.de, gleb@...nel.org,
alex.williamson@...hat.com
Cc: kvm@...r.kernel.org, linux-kernel@...r.kernel.org, wei@...hat.com,
sherry.hurwitz@....com
Subject: Re: [PART1 V5 13/13] svm: Manage vcpu load/unload when enable AVIC
On 10/05/2016 17:43, Paolo Bonzini wrote:
>
>
> On 04/05/2016 21:09, Suravee Suthikulpanit wrote:
>> From: Suravee Suthikulpanit <suravee.suthikulpanit@....com>
>>
>> When a vcpu is loaded/unloaded to a physical core, we need to update
>> host physical APIC ID information in the Physical APIC-ID table
>> accordingly.
>>
>> Also, when vCPU is blocking/un-blocking (due to halt instruction),
>> we need to make sure that the is-running bit in set accordingly in the
>> physical APIC-ID table.
>>
>> Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@....com>
>> Reviewed-by: Radim Krčmář <rkrcmar@...hat.com>
>> ---
>
> I think this is the only patch that needs a little more work, because
> there are a bunch of unused return values that really should be
> WARN_ON. In addition the load and put cases are different enough that
> they should be separate functions.
>
> Can you please test this?
>
> diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
> index f3dbf1d33a61..3168d6c8d24f 100644
> --- a/arch/x86/kvm/svm.c
> +++ b/arch/x86/kvm/svm.c
> @@ -184,7 +184,7 @@ struct vcpu_svm {
> u32 ldr_reg;
> struct page *avic_backing_page;
> u64 *avic_physical_id_cache;
> - bool avic_is_blocking;
> + bool avic_is_running;
> };
>
> #define AVIC_LOGICAL_ID_ENTRY_GUEST_PHYSICAL_ID_MASK (0xFF)
> @@ -1321,18 +1321,20 @@ free_avic:
> /**
> * This function is called during VCPU halt/unhalt.
> */
> -static int avic_set_running(struct kvm_vcpu *vcpu, bool is_run)
> +static void avic_set_running(struct kvm_vcpu *vcpu, bool is_run)
> {
> u64 entry;
> int h_physical_id = __default_cpu_present_to_apicid(vcpu->cpu);
> struct vcpu_svm *svm = to_svm(vcpu);
>
> if (!kvm_vcpu_apicv_active(vcpu))
> - return 0;
> + return;
> +
> + svm->avic_is_running = is_run;
>
> /* ID = 0xff (broadcast), ID > 0xff (reserved) */
> - if (h_physical_id >= AVIC_MAX_PHYSICAL_ID_COUNT)
> - return -EINVAL;
> + if (WARN_ON(h_physical_id >= AVIC_MAX_PHYSICAL_ID_COUNT))
> + return;
>
> entry = READ_ONCE(*(svm->avic_physical_id_cache));
> WARN_ON(is_run == !!(entry & AVIC_PHYSICAL_ID_ENTRY_IS_RUNNING_MASK));
> @@ -1341,36 +1343,45 @@ static int avic_set_running(struct kvm_vcpu *vcpu, bool is_run)
> if (is_run)
> entry |= AVIC_PHYSICAL_ID_ENTRY_IS_RUNNING_MASK;
> WRITE_ONCE(*(svm->avic_physical_id_cache), entry);
> -
> - return 0;
> }
>
> -static int avic_vcpu_load(struct kvm_vcpu *vcpu, int cpu, bool is_load)
> +static void avic_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
> {
> u64 entry;
> + /* ID = 0xff (broadcast), ID > 0xff (reserved) */
> int h_physical_id = __default_cpu_present_to_apicid(cpu);
> struct vcpu_svm *svm = to_svm(vcpu);
>
> if (!kvm_vcpu_apicv_active(vcpu))
> - return 0;
> + return;
>
> - /* ID = 0xff (broadcast), ID > 0xff (reserved) */
> - if (h_physical_id >= AVIC_MAX_PHYSICAL_ID_COUNT)
> - return -EINVAL;
> + if (WARN_ON(h_physical_id >= AVIC_MAX_PHYSICAL_ID_COUNT))
> + return;
>
> entry = READ_ONCE(*(svm->avic_physical_id_cache));
> - WARN_ON(is_load && (entry & AVIC_PHYSICAL_ID_ENTRY_IS_RUNNING_MASK));
> + WARN_ON(entry & AVIC_PHYSICAL_ID_ENTRY_IS_RUNNING_MASK);
> +
> + entry &= ~AVIC_PHYSICAL_ID_ENTRY_HOST_PHYSICAL_ID_MASK;
> + entry |= (h_physical_id & AVIC_PHYSICAL_ID_ENTRY_HOST_PHYSICAL_ID_MASK);
>
> entry &= ~AVIC_PHYSICAL_ID_ENTRY_IS_RUNNING_MASK;
> - if (is_load) {
> - entry &= ~AVIC_PHYSICAL_ID_ENTRY_HOST_PHYSICAL_ID_MASK;
> - entry |= (h_physical_id & AVIC_PHYSICAL_ID_ENTRY_HOST_PHYSICAL_ID_MASK);
> - if (!svm->avic_is_blocking)
> - entry |= AVIC_PHYSICAL_ID_ENTRY_IS_RUNNING_MASK;
> - }
> + if (svm->avic_is_running)
> + entry |= AVIC_PHYSICAL_ID_ENTRY_IS_RUNNING_MASK;
> +
> WRITE_ONCE(*(svm->avic_physical_id_cache), entry);
> +}
>
> - return 0;
> +static void avic_vcpu_put(struct kvm_vcpu *vcpu)
> +{
> + u64 entry;
> + struct vcpu_svm *svm = to_svm(vcpu);
> +
> + if (!kvm_vcpu_apicv_active(vcpu))
> + return;
> +
> + entry = READ_ONCE(*(svm->avic_physical_id_cache));
> + entry &= ~AVIC_PHYSICAL_ID_ENTRY_IS_RUNNING_MASK;
> + WRITE_ONCE(*(svm->avic_physical_id_cache), entry);
> }
>
> static void svm_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
> @@ -1436,10 +1447,10 @@ static struct kvm_vcpu *svm_create_vcpu(struct kvm *kvm, unsigned int id)
> goto free_page4;
> }
>
> - /* We initialize this flag to one to make sure that the is_running
> + /* We initialize this flag to true to make sure that the is_running
> * bit would be set the first time the vcpu is loaded.
> */
> - svm->avic_is_blocking = false;
> + svm->avic_is_running = true;
>
> svm->nested.hsave = page_address(hsave_page);
>
> @@ -1518,7 +1529,7 @@ static void svm_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
> if (static_cpu_has(X86_FEATURE_RDTSCP))
> wrmsrl(MSR_TSC_AUX, svm->tsc_aux);
>
> - avic_vcpu_load(vcpu, cpu, true);
> + avic_vcpu_load(vcpu, cpu);
> }
>
> static void svm_vcpu_put(struct kvm_vcpu *vcpu)
> @@ -1526,7 +1537,7 @@ static void svm_vcpu_put(struct kvm_vcpu *vcpu)
> struct vcpu_svm *svm = to_svm(vcpu);
> int i;
>
> - avic_vcpu_load(vcpu, 0, false);
> + avic_vcpu_put(vcpu);
>
> ++vcpu->stat.host_state_reload;
> kvm_load_ldt(svm->host.ldt);
> @@ -1545,13 +1556,11 @@ static void svm_vcpu_put(struct kvm_vcpu *vcpu)
>
> static void svm_vcpu_blocking(struct kvm_vcpu *vcpu)
> {
> - to_svm(vcpu)->avic_is_blocking = true;
> avic_set_running(vcpu, false);
> }
>
> static void svm_vcpu_unblocking(struct kvm_vcpu *vcpu)
> {
> - to_svm(vcpu)->avic_is_blocking = false;
> avic_set_running(vcpu, true);
> }
>
>
> The two functions now have the same signature as their callers,
> svm_vcpu_load and svm_vcpu_put.
Radim, does this look sane? I plan to include it in my pull request
(I'm running AMD autotest now and it passed the first few tests).
Thanks,
Paolo
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