Re: [PATCH v5] xen/x86: On x2APIC mode, derive LDR from APIC ID

2023-11-27 Thread Jan Beulich
On 27.11.2023 14:49, Alejandro Vallejo wrote: > On 27/11/2023 13:46, Alejandro Vallejo wrote: >> Both Intel and AMD manuals agree that on x2APIC mode, the APIC LDR and ID >> registers are derivable from each other through a fixed formula. >> >> Xen uses that formula, but applies it to vCPU IDs (whi

Re: [PATCH v5] xen/x86: On x2APIC mode, derive LDR from APIC ID

2023-11-27 Thread Alejandro Vallejo
On 27/11/2023 13:46, Alejandro Vallejo wrote: > Both Intel and AMD manuals agree that on x2APIC mode, the APIC LDR and ID > registers are derivable from each other through a fixed formula. > > Xen uses that formula, but applies it to vCPU IDs (which are sequential) > rather than x2APIC IDs (which

[PATCH v5] xen/x86: On x2APIC mode, derive LDR from APIC ID

2023-11-27 Thread Alejandro Vallejo
Both Intel and AMD manuals agree that on x2APIC mode, the APIC LDR and ID registers are derivable from each other through a fixed formula. Xen uses that formula, but applies it to vCPU IDs (which are sequential) rather than x2APIC IDs (which are not, at the moment). As I understand it, this is an