Messages in this thread | | | Date | Tue, 1 Feb 2022 21:56:55 +0700 | Subject | Re: [PATCH v3 3/3] KVM: SVM: Extend host physical APIC ID field to support more than 8-bit | From | "Suthikulpanit, Suravee" <> |
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Sean,
On 12/31/2021 12:21 AM, Sean Christopherson wrote: > On Mon, Dec 13, 2021, Suravee Suthikulpanit wrote: >> The AVIC physical APIC ID table entry contains the host physical >> APIC ID field, which the hardware uses to keep track of where each >> vCPU is running. Originally, the field is an 8-bit value, which can >> only support physical APIC ID up to 255. >> >> To support system with larger APIC ID, the AVIC hardware extends >> this field to support up to the largest possible physical APIC ID >> available on the system. >> >> Therefore, replace the hard-coded mask value with the value >> calculated from the maximum possible physical APIC ID in the system. > > ... > >> +static void avic_init_host_physical_apicid_mask(void) >> +{ >> + if (!x2apic_mode) { >> + /* If host is in xAPIC mode, default to only 8-bit mask. */ >> + avic_host_physical_id_mask = 0xffULL; > > Use GENMASK(7:0) instead of open coding the equivalent. Oh, and > avic_host_physical_id_mask doesn't need to be a u64, it's hard capped at 12 bits > and so can be a simple int. >
Actually, shouldn't it be u16 since the value returned from kvm_cpu_get_apicid() would typically be 16-bit value (despite it has int as a return type).
Regards, Suravee
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