Commit 2ce008c8 authored by Nicholas Piggin's avatar Nicholas Piggin Committed by Michael Ellerman
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KVM: PPC: Book3S HV: Remove unused nested HV tests in XICS emulation 



Commit f3c18e93 ("KVM: PPC: Book3S HV: Use XICS hypercalls when
running as a nested hypervisor") added nested HV tests in XICS
hypercalls, but not all are required.

* icp_eoi is only called by kvmppc_deliver_irq_passthru which is only
  called by kvmppc_check_passthru which is only caled by
  kvmppc_read_one_intr.

* kvmppc_read_one_intr is only called by kvmppc_read_intr which is only
  called by the L0 HV rmhandlers code.

* kvmhv_rm_send_ipi is called by:
  - kvmhv_interrupt_vcore which is only called by kvmhv_commence_exit
    which is only called by the L0 HV rmhandlers code.
  - icp_send_hcore_msg which is only called by icp_rm_set_vcpu_irq.
  - icp_rm_set_vcpu_irq which is only called by icp_rm_try_update
  - icp_rm_set_vcpu_irq is not nested HV safe because it writes to
    LPCR directly without a kvmhv_on_pseries test. Nested handlers
    should not in general be using the rm handlers.

The important test seems to be in kvmppc_ipi_thread, which sends the
virt-mode H_IPI handler kick to use smp_call_function rather than
msgsnd.

Signed-off-by: default avatarNicholas Piggin <npiggin@gmail.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210528090752.3542186-26-npiggin@gmail.com
parent dcbac73a

arch/powerpc/kvm/book3s_hv_builtin.c

+8 −36
Original line number Diff line number Diff line
@@ -199,15 +199,6 @@ void kvmhv_rm_send_ipi(int cpu) 
	void __iomem *xics_phys;

	unsigned long msg = PPC_DBELL_TYPE(PPC_DBELL_SERVER);



	/* For a nested hypervisor, use the XICS via hcall */

	if (kvmhv_on_pseries()) {

		unsigned long retbuf[PLPAR_HCALL_BUFSIZE];



		plpar_hcall_raw(H_IPI, retbuf, get_hard_smp_processor_id(cpu),

				IPI_PRIORITY);

		return;

	}



	/* On POWER9 we can use msgsnd for any destination cpu. */

	if (cpu_has_feature(CPU_FTR_ARCH_300)) {

		msg |= get_hard_smp_processor_id(cpu);
@@ -420,19 +411,12 @@ static long kvmppc_read_one_intr(bool *again) 
		return 1;



	/* Now read the interrupt from the ICP */

	if (kvmhv_on_pseries()) {

		unsigned long retbuf[PLPAR_HCALL_BUFSIZE];



		rc = plpar_hcall_raw(H_XIRR, retbuf, 0xFF);

		xirr = cpu_to_be32(retbuf[0]);

	} else {

	xics_phys = local_paca->kvm_hstate.xics_phys;

	rc = 0;

	if (!xics_phys)

		rc = opal_int_get_xirr(&xirr, false);

	else

		xirr = __raw_rm_readl(xics_phys + XICS_XIRR);

	}

	if (rc < 0)

		return 1;
@@ -461,13 +445,7 @@ static long kvmppc_read_one_intr(bool *again) 
	 */

	if (xisr == XICS_IPI) {

		rc = 0;

		if (kvmhv_on_pseries()) {

			unsigned long retbuf[PLPAR_HCALL_BUFSIZE];



			plpar_hcall_raw(H_IPI, retbuf,

					hard_smp_processor_id(), 0xff);

			plpar_hcall_raw(H_EOI, retbuf, h_xirr);

		} else if (xics_phys) {

		if (xics_phys) {

			__raw_rm_writeb(0xff, xics_phys + XICS_MFRR);

			__raw_rm_writel(xirr, xics_phys + XICS_XIRR);

		} else {
@@ -493,13 +471,7 @@ static long kvmppc_read_one_intr(bool *again) 
			/* We raced with the host,

			 * we need to resend that IPI, bummer

			 */

			if (kvmhv_on_pseries()) {

				unsigned long retbuf[PLPAR_HCALL_BUFSIZE];



				plpar_hcall_raw(H_IPI, retbuf,

						hard_smp_processor_id(),

						IPI_PRIORITY);

			} else if (xics_phys)

			if (xics_phys)

				__raw_rm_writeb(IPI_PRIORITY,

						xics_phys + XICS_MFRR);

			else

arch/powerpc/kvm/book3s_hv_rm_xics.c

+0 −15
Original line number Diff line number Diff line
@@ -141,13 +141,6 @@ static void icp_rm_set_vcpu_irq(struct kvm_vcpu *vcpu, 
		return;

	}



	if (xive_enabled() && kvmhv_on_pseries()) {

		/* No XICS access or hypercalls available, too hard */

		this_icp->rm_action |= XICS_RM_KICK_VCPU;

		this_icp->rm_kick_target = vcpu;

		return;

	}



	/*

	 * Check if the core is loaded,

	 * if not, find an available host core to post to wake the VCPU,
@@ -771,14 +764,6 @@ static void icp_eoi(struct irq_chip *c, u32 hwirq, __be32 xirr, bool *again) 
	void __iomem *xics_phys;

	int64_t rc;



	if (kvmhv_on_pseries()) {

		unsigned long retbuf[PLPAR_HCALL_BUFSIZE];



		iosync();

		plpar_hcall_raw(H_EOI, retbuf, hwirq);

		return;

	}



	rc = pnv_opal_pci_msi_eoi(c, hwirq);



	if (rc)