Commit b2236495 authored by Sean Christopherson's avatar Sean Christopherson
Browse files

KVM: x86: Mark x2APIC DFR reg as non-existent for x2APIC 



Mark APIC_DFR as being invalid/non-existent in x2APIC mode instead of
handling it as a one-off check in kvm_x2apic_msr_read().  This will allow
reusing "valid_reg_mask" to generate VMX's interception bitmaps for
x2APIC.  Handling DFR in the common read path may also fix the Hyper-V
PV MSR interface, if that can coexist with x2APIC.

Reviewed-by: default avatarMaxim Levitsky <mlevitsk@redhat.com>
Link: https://lore.kernel.org/r/20230107011025.565472-4-seanjc@google.com


Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
parent ab52be1b

arch/x86/kvm/lapic.c

+4 −7
Original line number Diff line number Diff line
@@ -1573,7 +1573,6 @@ static int kvm_lapic_reg_read(struct kvm_lapic *apic, u32 offset, int len, 
		APIC_REG_MASK(APIC_TASKPRI) |

		APIC_REG_MASK(APIC_PROCPRI) |

		APIC_REG_MASK(APIC_LDR) |

		APIC_REG_MASK(APIC_DFR) |

		APIC_REG_MASK(APIC_SPIV) |

		APIC_REGS_MASK(APIC_ISR, APIC_ISR_NR) |

		APIC_REGS_MASK(APIC_TMR, APIC_ISR_NR) |
@@ -1594,12 +1593,13 @@ static int kvm_lapic_reg_read(struct kvm_lapic *apic, u32 offset, int len, 
		valid_reg_mask |= APIC_REG_MASK(APIC_LVTCMCI);



	/*

	 * ARBPRI and ICR2 are not valid in x2APIC mode.  WARN if KVM reads ICR

	 * in x2APIC mode as it's an 8-byte register in x2APIC and needs to be

	 * manually handled by the caller.

	 * ARBPRI, DFR, and ICR2 are not valid in x2APIC mode.  WARN if KVM

	 * reads ICR in x2APIC mode as it's an 8-byte register in x2APIC and

	 * needs to be manually handled by the caller.

	 */

	if (!apic_x2apic_mode(apic))

		valid_reg_mask |= APIC_REG_MASK(APIC_ARBPRI) |

				  APIC_REG_MASK(APIC_DFR) |

				  APIC_REG_MASK(APIC_ICR2);

	else

		WARN_ON_ONCE(offset == APIC_ICR);
@@ -3147,9 +3147,6 @@ int kvm_x2apic_msr_read(struct kvm_vcpu *vcpu, u32 msr, u64 *data) 
	if (!lapic_in_kernel(vcpu) || !apic_x2apic_mode(apic))

		return 1;



	if (reg == APIC_DFR)

		return 1;



	return kvm_lapic_msr_read(apic, reg, data);

}