From: Fuad Tabba <fuad.tabba@linux.dev>
To: Marc Zyngier <maz@kernel.org>
Cc: Oliver Upton <oupton@kernel.org>, Joey Gouly <joey.gouly@arm.com>,
Steffen Eiden <seiden@linux.ibm.com>,
Suzuki K Poulose <suzuki.poulose@arm.com>,
Zenghui Yu <yuzenghui@huawei.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
Vincent Donnefort <vdonnefort@google.com>,
Quentin Perret <qperret@google.com>,
Fuad Tabba <tabba@google.com>,
kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/2] KVM: arm64: Track physical CPU number at EL2
Date: Mon, 19 Oct 2026 12:43:56 +0100 [thread overview]
Message-ID: <20261019114356.3528307-1-fuad.tabba@linux.dev> (raw)
In-Reply-To: <86y0buyo5s.wl-maz@kernel.org>
Hi Marc,
On Mon, 19 Oct 2026 11:34:23 +0100, Marc Zyngier <maz@kernel.org> wrote:
[...]
> > diff --git a/arch/arm64/include/asm/kvm_hyp.h b/arch/arm64/include/asm/kvm_hyp.h
[...]
> > +DECLARE_PER_CPU(int, hyp_cpu_number);
> > +
> > +#define hyp_smp_processor_id() (__this_cpu_read(hyp_cpu_number))
> >
>
> Do we really need this? I was hoping that TPIDR_EL2 would give us a
> way to compute the CPU number more or less directly, without having to
> maintain per-CPU variable (which is pretty backward, when you think
> about it...).
No. There's no direct way from TPIDR_EL2 to the CPU number, since
init_hyp_mode() allocates each CPU's hyp per-CPU area separately, but
patch 2 can do without the number. I'll drop this patch in v2, and
patch 2 will keep the last vCPU in a per-CPU array indexed by the VM's
table entry.
Cheers,
/fuad
next prev parent reply other threads:[~2026-10-19 11:43 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-10-14 12:55 [PATCH 0/2] KVM: arm64: Per-vCPU TLB and I-cache flush in pKVM Fuad Tabba
2026-10-14 12:55 ` [PATCH 1/2] KVM: arm64: Track physical CPU number at EL2 Fuad Tabba
2026-10-19 10:34 ` Marc Zyngier
2026-10-19 11:43 ` Fuad Tabba [this message]
2026-10-14 12:55 ` [PATCH 2/2] KVM: arm64: Ensure TLBs and I-cache are private to each vCPU in pKVM Fuad Tabba
2026-10-14 15:53 ` Joey Gouly
2026-10-19 11:43 ` Fuad Tabba
2026-10-19 10:00 ` Vincent Donnefort
2026-10-19 11:43 ` Fuad Tabba
2026-10-19 12:39 ` Vincent Donnefort
2026-10-19 12:42 ` Vincent Donnefort
2026-10-19 12:45 ` Fuad Tabba
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