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riscv: KVM: Fix SBI IPI error generation

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When an invalid function ID of an SBI extension is used we should
return not-supported, not invalid-param. Also, when we see that at
least one hartid constructed from the base and mask parameters is
invalid, then we should return invalid-param. Finally, rather than
relying on overflowing a left shift to result in zero and then using
that zero in a condition which [correctly] skips sending an IPI (but
loops unnecessarily), explicitly check for overflow and exit the loop
immediately.

Fixes: 5f862df558 ("RISC-V: KVM: Add v0.1 replacement SBI extensions defined in v0.2")
Signed-off-by: Andrew Jones <ajones@ventanamicro.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
Link: https://lore.kernel.org/r/20250217084506.18763-10-ajones@ventanamicro.com
Signed-off-by: Anup Patel <anup@brainfault.org>
This commit is contained in:
Andrew Jones 2025-02-17 09:45:10 +01:00 • committed by Anup Patel
parent e3219b0c49
commit 0611f78f83
1 changed files with 11 additions and 2 deletions
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13
arch/riscv/kvm/vcpu_sbi_replace.c
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@ -51,9 +51,10 @@ static int kvm_sbi_ext_ipi_handler(struct kvm_vcpu *vcpu, struct kvm_run *run,
struct kvm_cpu_context *cp = &vcpu->arch.guest_context;
unsigned long hmask = cp->a0;
unsigned long hbase = cp->a1;
unsigned long hart_bit = 0, sentmask = 0;
if (cp->a6 != SBI_EXT_IPI_SEND_IPI) {
retdata->err_val = SBI_ERR_INVALID_PARAM;
retdata->err_val = SBI_ERR_NOT_SUPPORTED;
return 0;
}
@ -62,15 +63,23 @@ static int kvm_sbi_ext_ipi_handler(struct kvm_vcpu *vcpu, struct kvm_run *run,
if (hbase != -1UL) {
if (tmp->vcpu_id < hbase)
continue;
if (!(hmask & (1UL << (tmp->vcpu_id - hbase))))
hart_bit = tmp->vcpu_id - hbase;
if (hart_bit >= __riscv_xlen)
goto done;
if (!(hmask & (1UL << hart_bit)))
continue;
}
ret = kvm_riscv_vcpu_set_interrupt(tmp, IRQ_VS_SOFT);
if (ret < 0)
break;
sentmask |= 1UL << hart_bit;
kvm_riscv_vcpu_pmu_incr_fw(tmp, SBI_PMU_FW_IPI_RCVD);
}
done:
if (hbase != -1UL && (hmask ^ sentmask))
retdata->err_val = SBI_ERR_INVALID_PARAM;
return ret;
}