From: Mark Brown <broonie@kernel.org>
To: Marc Zyngier <maz@kernel.org>
Cc: Oliver Upton <oliver.upton@linux.dev>,
James Morse <james.morse@arm.com>,
Suzuki K Poulose <suzuki.poulose@arm.com>,
Zenghui Yu <yuzenghui@huawei.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>, Joey Gouly <joey.gouly@arm.com>,
linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev
Subject: Re: [PATCH v2 2/2] KVM: arm64: Move FGT value configuration to vCPU state
Date: Thu, 23 Mar 2023 22:08:44 +0000 [thread overview]
Message-ID: <4f6a5565-af40-4bde-8aaf-5470e9562b0e@sirena.org.uk> (raw)
In-Reply-To: <865yarxnwv.wl-maz@kernel.org>
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On Thu, Mar 23, 2023 at 07:34:08PM +0000, Marc Zyngier wrote:
> Mark Brown <broonie@kernel.org> wrote:
> > +++ b/arch/arm64/include/asm/kvm_host.h
> > @@ -365,6 +365,8 @@ enum vcpu_sysreg {
> > TPIDR_EL2, /* EL2 Software Thread ID Register */
> > CNTHCTL_EL2, /* Counter-timer Hypervisor Control register */
> > SP_EL2, /* EL2 Stack Pointer */
> > + HFGRTR_EL2, /* Fine Grained Read Traps */
> > + HFGWTR_EL2, /* Fine Grained Write Traps */
> No, this is the wrong spot. These registers describe the *guest*
> state. Not the state that KVM sets for its own use. These registers
> would be used by a guest hypervisor to manage traps it uses for its
> own guests.
Ah, sorry, I misinterpreted what you meant when you said to put them in
kvm_vcpu_context - the sys_regs array in there seemed to be the place
where data for sysregs is stored. The large set of EL2 registers in
there already stopped alarm bells going off, as did the fact that with
the patch above we were loading a copy from there for the guest.
To clarify, place just regular member variables in kvm_vcpu_context then
save host state to the percpu host context (I guess while activating
traps) and load the guest state from vcpu->arch.ctxt.hfgxtr_el2? I've
got that testing locally just now.
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next prev parent reply other threads:[~2023-03-23 22:08 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-03-23 15:48 [PATCH v2 0/2] KVM: arm64: Support for per-guest fine grained traps configuration Mark Brown
2023-03-23 15:48 ` [PATCH v2 1/2] arm64: Add feature detection for fine grained traps Mark Brown
2023-03-23 15:48 ` [PATCH v2 2/2] KVM: arm64: Move FGT value configuration to vCPU state Mark Brown
2023-03-23 19:34 ` Marc Zyngier
2023-03-23 22:08 ` Mark Brown [this message]
2023-03-28 15:27 ` Will Deacon
2023-03-28 15:44 ` Mark Brown
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