Commit d0d81e03 authored by Oliver Upton's avatar Oliver Upton
Browse files

KVM: arm64: Load VPIDR_EL2 with the VM's MIDR_EL1 value 

Userspace will soon be able to change the value of MIDR_EL1. Prepare by
loading VPIDR_EL2 with the guest value for non-nested VMs.

Since VPIDR_EL2 is set for any VM, get rid of the NV-specific cleanup of
reloading the hardware value on vcpu_put(). And for nVHE, load the
hardware value before switching to the host.

Link: https://lore.kernel.org/r/20250225005401.679536-4-oliver.upton@linux.dev


Signed-off-by: default avatarOliver Upton <oliver.upton@linux.dev>
parent b4043e7c

arch/arm64/kvm/hyp/include/hyp/sysreg-sr.h

+7 −1
Original line number Diff line number Diff line
@@ -43,6 +43,11 @@ static inline u64 *ctxt_mdscr_el1(struct kvm_cpu_context *ctxt) 
	return &ctxt_sys_reg(ctxt, MDSCR_EL1);

}



static inline u64 ctxt_midr_el1(struct kvm_cpu_context *ctxt)

{

	return read_cpuid_id();

}



static inline void __sysreg_save_common_state(struct kvm_cpu_context *ctxt)

{

	*ctxt_mdscr_el1(ctxt)	= read_sysreg(mdscr_el1);
@@ -168,8 +173,9 @@ static inline void __sysreg_restore_user_state(struct kvm_cpu_context *ctxt) 
}



static inline void __sysreg_restore_el1_state(struct kvm_cpu_context *ctxt,

					      u64 mpidr)

					      u64 midr, u64 mpidr)

{

	write_sysreg(midr,				vpidr_el2);

	write_sysreg(mpidr,				vmpidr_el2);



	if (has_vhe() ||

arch/arm64/kvm/hyp/nvhe/sysreg-sr.c

+3 −1
Original line number Diff line number Diff line
@@ -28,7 +28,9 @@ void __sysreg_save_state_nvhe(struct kvm_cpu_context *ctxt) 


void __sysreg_restore_state_nvhe(struct kvm_cpu_context *ctxt)

{

	__sysreg_restore_el1_state(ctxt, ctxt_sys_reg(ctxt, MPIDR_EL1));

	u64 midr = ctxt_midr_el1(ctxt);



	__sysreg_restore_el1_state(ctxt, midr, ctxt_sys_reg(ctxt, MPIDR_EL1));

	__sysreg_restore_common_state(ctxt);

	__sysreg_restore_user_state(ctxt);

	__sysreg_restore_el2_return_state(ctxt);

arch/arm64/kvm/hyp/vhe/sysreg-sr.c

+10 −18
Original line number Diff line number Diff line
@@ -87,6 +87,7 @@ static void __sysreg_restore_vel2_state(struct kvm_vcpu *vcpu) 
	write_sysreg(__vcpu_sys_reg(vcpu, PAR_EL1),	par_el1);

	write_sysreg(__vcpu_sys_reg(vcpu, TPIDR_EL1),	tpidr_el1);



	write_sysreg(ctxt_midr_el1(&vcpu->arch.ctxt),			vpidr_el2);

	write_sysreg(__vcpu_sys_reg(vcpu, MPIDR_EL1),			vmpidr_el2);

	write_sysreg_el1(__vcpu_sys_reg(vcpu, MAIR_EL2),		SYS_MAIR);

	write_sysreg_el1(__vcpu_sys_reg(vcpu, VBAR_EL2),		SYS_VBAR);
@@ -191,7 +192,7 @@ void __vcpu_load_switch_sysregs(struct kvm_vcpu *vcpu) 
{

	struct kvm_cpu_context *guest_ctxt = &vcpu->arch.ctxt;

	struct kvm_cpu_context *host_ctxt;

	u64 mpidr;

	u64 midr, mpidr;



	host_ctxt = host_data_ptr(host_ctxt);

	__sysreg_save_user_state(host_ctxt);
@@ -220,23 +221,18 @@ void __vcpu_load_switch_sysregs(struct kvm_vcpu *vcpu) 
		__sysreg_restore_vel2_state(vcpu);

	} else {

		if (vcpu_has_nv(vcpu)) {

			/*

			 * Use the guest hypervisor's VPIDR_EL2 when in a

			 * nested state. The hardware value of MIDR_EL1 gets

			 * restored on put.

			 */

			write_sysreg(ctxt_sys_reg(guest_ctxt, VPIDR_EL2), vpidr_el2);



			/*

			 * As we're restoring a nested guest, set the value

			 * provided by the guest hypervisor.

			 */

			midr = ctxt_sys_reg(guest_ctxt, VPIDR_EL2);

			mpidr = ctxt_sys_reg(guest_ctxt, VMPIDR_EL2);

		} else {

			midr = ctxt_midr_el1(guest_ctxt);

			mpidr = ctxt_sys_reg(guest_ctxt, MPIDR_EL1);

		}



		__sysreg_restore_el1_state(guest_ctxt, mpidr);

		__sysreg_restore_el1_state(guest_ctxt, midr, mpidr);

	}



	vcpu_set_flag(vcpu, SYSREGS_ON_CPU);
@@ -271,9 +267,5 @@ void __vcpu_put_switch_sysregs(struct kvm_vcpu *vcpu) 
	/* Restore host user state */

	__sysreg_restore_user_state(host_ctxt);



	/* If leaving a nesting guest, restore MIDR_EL1 default view */

	if (vcpu_has_nv(vcpu))

		write_sysreg(read_cpuid_id(),	vpidr_el2);



	vcpu_clear_flag(vcpu, SYSREGS_ON_CPU);

}