linux-kernel - [PATCH kernel] KVM: PPC: Book3S HV: Make unique debugfs nodename

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Date:   Wed,  7 Jul 2021 14:13:44 +1000
From:   Alexey Kardashevskiy <aik@...abs.ru>
To:     linuxppc-dev@...ts.ozlabs.org
Cc:     Alexey Kardashevskiy <aik@...abs.ru>, linux-kernel@...r.kernel.org,
        kvm-ppc@...r.kernel.org, Paul Mackerras <paulus@...abs.org>
Subject: [PATCH kernel] KVM: PPC: Book3S HV: Make unique debugfs nodename

Currently it is vm-$currentpid which works as long as there is just one
VM per the userspace (99.99% cases) but produces a bunch
of "debugfs: Directory 'vm16679' with parent 'kvm' already present!"
when syzkaller (syscall fuzzer) is running so only one VM is present in
the debugfs for a given process.

This changes the debugfs node to include the LPID which alone should be
system wide unique. This leaves the existing pid for the convenience of
matching the VM's debugfs with the running userspace process (QEMU).

Signed-off-by: Alexey Kardashevskiy <aik@...abs.ru>
---
 arch/powerpc/kvm/book3s_hv.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
index 1d1fcc290fca..0223ddc0eed0 100644
--- a/arch/powerpc/kvm/book3s_hv.c
+++ b/arch/powerpc/kvm/book3s_hv.c
@@ -5227,7 +5227,7 @@ static int kvmppc_core_init_vm_hv(struct kvm *kvm)
 	/*
 	 * Create a debugfs directory for the VM
 	 */
-	snprintf(buf, sizeof(buf), "vm%d", current->pid);
+	snprintf(buf, sizeof(buf), "vm%d-lp%ld", current->pid, lpid);
 	kvm->arch.debugfs_dir = debugfs_create_dir(buf, kvm_debugfs_dir);
 	kvmppc_mmu_debugfs_init(kvm);
 	if (radix_enabled())
-- 
2.30.2