From: Vaibhav Jain <vaibhav@linux.ibm.com>
To: "Aneesh Kumar K.V" <aneesh.kumar@kernel.org>,
linuxppc-dev@lists.ozlabs.org, kvm@vger.kernel.org,
kvm-ppc@vger.kernel.org
Cc: Nicholas Piggin <npiggin@gmail.com>,
Michael Ellerman <mpe@ellerman.id.au>,
Jordan Niethe <jniethe5@gmail.com>,
Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com>,
mikey@neuling.org, paulus@ozlabs.org, sbhat@linux.ibm.com,
gautam@linux.ibm.com, kconsul@linux.vnet.ibm.com,
amachhiw@linux.vnet.ibm.com, David.Laight@ACULAB.COM
Subject: Re: [PATCH 09/12] KVM: PPC: Book3S HV nestedv2: Do not call H_COPY_TOFROM_GUEST
Date: Mon, 18 Dec 2023 12:32:39 +0530 [thread overview]
Message-ID: <87zfy89enk.fsf@vajain21.in.ibm.com> (raw)
In-Reply-To: <086fb48f-ea7c-4b4e-b3b5-c930aa74bbb2@kernel.org>
Hi Aneesh,
"Aneesh Kumar K.V" <aneesh.kumar@kernel.org> writes:
<snip>
>> Yes, Agreed and thats a nice suggestion. However ATM the hypervisor
>> supporting Nestedv2 doesnt have support for this hcall. In future
>> once we have support for this hcall for nestedv2 from the hypervisor
>> we can replace this branch with a firmware_has_feature() test.
>>
>
> What I am suggesting is we convert that conditional to firmware_has_feature so that
> later when hypervisor supports this hcall all older kernel can make
> use of the copy_tofrom_guest without any code change.
AFAIK for firmware_has_feature to work we either need:
- A way to call this hcall with some invalid args. However lpid/pid for
guest arent allocated during boot.
- A way for hypervisor to advertise support for this hcall before the L1
kernel boots.
ATM L0 dosent support for any of these two ways. I can do a follow up
patch later when we have a clarity on how we want to advertise support
for this hcall. For now current kernel supporting nestedv2 wont be
using this hcall assuming its not supported. Future kernels can use one
of the two ways above to set the firmware_has_feature flag to take
advantage of this hcall.
--
Cheers
~ Vaibhav
next prev parent reply other threads:[~2023-12-18 7:03 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-12-01 13:26 [PATCH 00/12] KVM: PPC: Nested APIv2 : Performance improvements Vaibhav Jain
2023-12-01 13:26 ` [PATCH 01/12] KVM: PPC: Book3S HV nestedv2: Invalidate RPT before deleting a guest Vaibhav Jain
2023-12-07 9:15 ` Aneesh Kumar K.V
2023-12-08 13:45 ` Vaibhav Jain
2023-12-15 16:12 ` Aneesh Kumar K.V
2023-12-18 4:54 ` Vaibhav Jain
2023-12-01 13:26 ` [PATCH 02/12] KVM: PPC: Book3S HV nestedv2: Avoid reloading the tb offset Vaibhav Jain
2023-12-01 13:26 ` [PATCH 03/12] KVM: PPC: Book3S HV nestedv2: Do not check msr on hcalls Vaibhav Jain
2023-12-01 13:26 ` [PATCH 04/12] KVM: PPC: Book3S HV nestedv2: Get the PID only if needed to copy tofrom a guest Vaibhav Jain
2023-12-01 13:26 ` [PATCH 05/12] KVM: PPC: Book3S HV nestedv2: Ensure LPCR_MER bit is passed to the L0 Vaibhav Jain
2023-12-01 13:26 ` [PATCH 06/12] KVM: PPC: Book3S HV: Handle pending exceptions on guest entry with MSR_EE Vaibhav Jain
2023-12-01 13:26 ` [PATCH 07/12] KVM: PPC: Book3S HV nestedv2: Do not inject certain interrupts Vaibhav Jain
2023-12-01 13:26 ` [PATCH 08/12] KVM: PPC: Book3S HV nestedv2: Avoid msr check in kvmppc_handle_exit_hv() Vaibhav Jain
2023-12-01 13:26 ` [PATCH 09/12] KVM: PPC: Book3S HV nestedv2: Do not call H_COPY_TOFROM_GUEST Vaibhav Jain
2023-12-08 8:15 ` Aneesh Kumar K.V
2023-12-11 3:56 ` Vaibhav Jain
2023-12-11 4:01 ` Aneesh Kumar K.V
2023-12-18 7:02 ` Vaibhav Jain [this message]
2023-12-18 7:29 ` Aneesh Kumar K.V
2023-12-01 13:26 ` [PATCH 10/12] KVM: PPC: Book3S HV nestedv2: Register the VPA with the L0 Vaibhav Jain
2023-12-01 13:26 ` [PATCH 11/12] KVM: PPC: Reduce reliance on analyse_instr() in mmio emulation Vaibhav Jain
2023-12-01 13:26 ` [PATCH 12/12] KVM: PPC: Book3S HV nestedv2: Do not cancel pending decrementer exception Vaibhav Jain
2023-12-21 10:44 ` [PATCH 00/12] KVM: PPC: Nested APIv2 : Performance improvements Michael Ellerman
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