Messages in this thread | | | From | Jianyong Wu <> | Subject | RE: [PATCH] arm64/kvm: Introduce feature extension for SMCCC filter | Date | Tue, 21 Nov 2023 01:58:08 +0000 |
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> -----Original Message----- > From: Salil Mehta <salil.mehta@huawei.com> > Sent: 2023年11月16日 22:06 > To: Cornelia Huck <cohuck@redhat.com>; Jianyong Wu > <Jianyong.Wu@arm.com>; maz@kernel.org; James Morse > <James.Morse@arm.com>; will@kernel.org > Cc: rmk@armlinux.org.uk; Suzuki Poulose <Suzuki.Poulose@arm.com>; > oliver.upton@linux.dev; linux-arm-kernel@lists.infradead.org; > kvmarm@lists.linux.dev; linux-kernel@vger.kernel.org; Justin He > <Justin.He@arm.com>; Jianyong Wu <Jianyong.Wu@arm.com> > Subject: RE: [PATCH] arm64/kvm: Introduce feature extension for SMCCC filter > > > From: Cornelia Huck <cohuck@redhat.com> > > Sent: Thursday, November 16, 2023 1:09 PM > > To: Jianyong Wu <jianyong.wu@arm.com>; maz@kernel.org; > > james.morse@arm.com; will@kernel.org > > > > On Thu, Nov 16 2023, Jianyong Wu <jianyong.wu@arm.com> wrote: > > > > > 821d935c87b introduces support for userspace SMCCC filtering, but > > > lack of a way to tell userspace if we have this feature. Add a > > > corresponding feature extension can resolve this issue. > > > > > > For example, the incoming feature Vcpu Hotplug needs the SMCCC filter. > > > As there is no way to check this feature, VMM will run into error > > > when it calls this feature on an old kernel. It's bad for backward compatible. > > > > Can't you simply query via KVM_HAS_DEVICE_ATTR whether the SMCCC > > filtering controls exist? > > > Agreed. In fact, this is what I had earlier intended to do but deferred this change. > As of now, RFC V2 of vCPU Hotplug series does not have this check yet while > installing the SMCCC filters in KVM Host. >
Yes, we can use KVM_HAS_DEVICE_ATTR to do the check in userspace. Thanks Cornelia.
Thanks Jianyong
> Thanks > > > > Signed-off-by: Jianyong Wu <jianyong.wu@arm.com> > > > --- > > > Documentation/virt/kvm/api.rst | 3 ++- > > > arch/arm64/kvm/arm.c | 1 + > > > include/uapi/linux/kvm.h | 1 + > > > 3 files changed, 4 insertions(+), 1 deletion(-) > > >
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