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Thu, 7 Feb 2019 09:13:49 +0000 (UTC) Subject: Re: [PATCH 15/19] KVM: PPC: Book3S HV: add get/set accessors for the source configuration To: David Gibson References: <20190107184331.8429-1-clg@kaod.org> <20190107184331.8429-16-clg@kaod.org> <20190204052148.GH1927@umbus.fritz.box> <02ee0470-3c6a-5c5c-a903-44e172ce1ed5@kaod.org> <20190205053233.GG22661@umbus.fritz.box> <20190206012329.GQ22661@umbus.fritz.box> <20190206012447.GR22661@umbus.fritz.box> <1d92005a-c12d-1a55-d01b-98eded13629c@kaod.org> <20190207024855.GZ22661@umbus.fritz.box> From: =?UTF-8?Q?C=c3=a9dric_Le_Goater?= Message-ID: <9f03f232-1c47-6e27-6d79-3bcc900fe943@kaod.org> Date: Thu, 7 Feb 2019 10:13:48 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.4.0 MIME-Version: 1.0 In-Reply-To: <20190207024855.GZ22661@umbus.fritz.box> Content-Type: text/plain; charset=windows-1252 Content-Language: en-US Content-Transfer-Encoding: 8bit X-Ovh-Tracer-Id: 17785840831576181639 X-VR-SPAMSTATE: OK X-VR-SPAMSCORE: -100 X-VR-SPAMCAUSE: gggruggvucftvghtrhhoucdtuddrgedtledrledtgddtvdcutefuodetggdotefrodftvfcurfhrohhfihhlvgemucfqggfjpdevjffgvefmvefgnecuuegrihhlohhuthemucehtddtnecusecvtfgvtghiphhivghnthhsucdlqddutddtmd X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: kvm@vger.kernel.org, kvm-ppc@vger.kernel.org, Paul Mackerras , linuxppc-dev@lists.ozlabs.org Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On 2/7/19 3:48 AM, David Gibson wrote: > On Wed, Feb 06, 2019 at 08:07:36AM +0100, Cédric Le Goater wrote: >> On 2/6/19 2:24 AM, David Gibson wrote: >>> On Wed, Feb 06, 2019 at 12:23:29PM +1100, David Gibson wrote: >>>> On Tue, Feb 05, 2019 at 02:03:11PM +0100, Cédric Le Goater wrote: >>>>> On 2/5/19 6:32 AM, David Gibson wrote: >>>>>> On Mon, Feb 04, 2019 at 05:07:28PM +0100, Cédric Le Goater wrote: >>>>>>> On 2/4/19 6:21 AM, David Gibson wrote: >>>>>>>> On Mon, Jan 07, 2019 at 07:43:27PM +0100, Cédric Le Goater wrote: >>>>>>>>> Theses are use to capure the XIVE EAS table of the KVM device, the >>>>>>>>> configuration of the source targets. >>>>>>>>> >>>>>>>>> Signed-off-by: Cédric Le Goater >>>>>>>>> --- >>>>>>>>> arch/powerpc/include/uapi/asm/kvm.h | 11 ++++ >>>>>>>>> arch/powerpc/kvm/book3s_xive_native.c | 87 +++++++++++++++++++++++++++ >>>>>>>>> 2 files changed, 98 insertions(+) >>>>>>>>> >>>>>>>>> diff --git a/arch/powerpc/include/uapi/asm/kvm.h b/arch/powerpc/include/uapi/asm/kvm.h >>>>>>>>> index 1a8740629acf..faf024f39858 100644 >>>>>>>>> --- a/arch/powerpc/include/uapi/asm/kvm.h >>>>>>>>> +++ b/arch/powerpc/include/uapi/asm/kvm.h >>>>>>>>> @@ -683,9 +683,20 @@ struct kvm_ppc_cpu_char { >>>>>>>>> #define KVM_DEV_XIVE_SAVE_EQ_PAGES 4 >>>>>>>>> #define KVM_DEV_XIVE_GRP_SOURCES 2 /* 64-bit source attributes */ >>>>>>>>> #define KVM_DEV_XIVE_GRP_SYNC 3 /* 64-bit source attributes */ >>>>>>>>> +#define KVM_DEV_XIVE_GRP_EAS 4 /* 64-bit eas attributes */ >>>>>>>>> >>>>>>>>> /* Layout of 64-bit XIVE source attribute values */ >>>>>>>>> #define KVM_XIVE_LEVEL_SENSITIVE (1ULL << 0) >>>>>>>>> #define KVM_XIVE_LEVEL_ASSERTED (1ULL << 1) >>>>>>>>> >>>>>>>>> +/* Layout of 64-bit eas attribute values */ >>>>>>>>> +#define KVM_XIVE_EAS_PRIORITY_SHIFT 0 >>>>>>>>> +#define KVM_XIVE_EAS_PRIORITY_MASK 0x7 >>>>>>>>> +#define KVM_XIVE_EAS_SERVER_SHIFT 3 >>>>>>>>> +#define KVM_XIVE_EAS_SERVER_MASK 0xfffffff8ULL >>>>>>>>> +#define KVM_XIVE_EAS_MASK_SHIFT 32 >>>>>>>>> +#define KVM_XIVE_EAS_MASK_MASK 0x100000000ULL >>>>>>>>> +#define KVM_XIVE_EAS_EISN_SHIFT 33 >>>>>>>>> +#define KVM_XIVE_EAS_EISN_MASK 0xfffffffe00000000ULL >>>>>>>>> + >>>>>>>>> #endif /* __LINUX_KVM_POWERPC_H */ >>>>>>>>> diff --git a/arch/powerpc/kvm/book3s_xive_native.c b/arch/powerpc/kvm/book3s_xive_native.c >>>>>>>>> index f2de1bcf3b35..0468b605baa7 100644 >>>>>>>>> --- a/arch/powerpc/kvm/book3s_xive_native.c >>>>>>>>> +++ b/arch/powerpc/kvm/book3s_xive_native.c >>>>>>>>> @@ -525,6 +525,88 @@ static int kvmppc_xive_native_sync(struct kvmppc_xive *xive, long irq, u64 addr) >>>>>>>>> return 0; >>>>>>>>> } >>>>>>>>> >>>>>>>>> +static int kvmppc_xive_native_set_eas(struct kvmppc_xive *xive, long irq, >>>>>>>>> + u64 addr) >>>>>>>> >>>>>>>> I'd prefer to avoid the name "EAS" here. IIUC these aren't "raw" EAS >>>>>>>> values, but rather essentially the "source config" in the terminology >>>>>>>> of the PAPR hcalls. Which, yes, is basically implemented by setting >>>>>>>> the EAS, but since it's the PAPR architected state that we need to >>>>>>>> preserve across migration, I'd prefer to stick as close as we can to >>>>>>>> the PAPR terminology. >>>>>>> >>>>>>> But we don't have an equivalent name in the PAPR specs for the tuple >>>>>>> (prio, server). We could use the generic 'target' name may be ? even >>>>>>> if this is usually referring to a CPU number. >>>>>> >>>>>> Um.. what? That's about terminology for one of the fields in this >>>>>> thing, not about the name for the thing itself. >>>>>> >>>>>>> Or, IVE (Interrupt Vector Entry) ? which makes some sense. >>>>>>> This is was the former name in HW. I think we recycle it for KVM. >>>>>> >>>>>> That's a terrible idea, which will make a confusing situation even >>>>>> more confusing. >>>>> >>>>> Let's use SOURCE_CONFIG and QUEUE_CONFIG. The KVM ioctls are very >>>>> similar to the hcalls anyhow. >>>> >>>> Yes, I think that's a good idea. >>> >>> Actually... AIUI the SET_CONFIG hcalls shouldn't be a fast path. >> >> No indeed. I have move them to standard hcalls in the current version. >> >>> Can >>> we simplify things further by removing the hcall implementation from >>> the kernel entirely, and have qemu implement them by basically just >>> forwarding them to the appropriate SET_CONFIG ioctl()? >> >> Yes. I think we could. > > Great! > >> The hcalls H_INT_SET_SOURCE_CONFIG and H_INT_SET_QUEUE_CONFIG and >> the KVM ioctls to set the EQ and the SOURCE configuration have a >> lot in common. I need to look at how we can plug the KVM ioctl in >> the hcalls under QEMU. >> >> We will have to convert the returned error to respect the PAPR >> specs or have the ioctls return H_* errors. > > I don't think returning H_* values from a kernel call is a good idea. > Converting errors is kinda ugly, but I still think it's the better > option. Note that we already have something like this for the HPT > resizing hcalls. ok. >> Let's dig that idea. If we choose that path, QEMU will have an >> up-to-date EAT and so we won't need to synchronize its state anymore >> for migration. > > I guess so, though I don't see that as essential. > >> H_INT_GET_SOURCE_CONFIG can be implemented in QEMU without any KVM >> ioctl. >> >> H_INT_GET_QUEUE_INFO could be implemented in QEMU. I need to check >> how we return the address of the END ESB in sPAPR. We haven't paid >> much attention to these pages because they are not used under Linux >> and today the address is returned by OPAL. >> >> H_INT_GET_QUEUE_CONFIG is a little more problematic because we need >> to query into the XIVE HW the EQ index and toggle bit. OPAL support >> is required for that. But we could reduce the KVM support to the >> ioctl querying these EQ information. > > Right, and we'd need an ioctl() like that for migration anyway, yes? Yes. it is the same need. >> H_INT_ESB could be entirely done under QEMU. > > This one can actually happen on fairly hot paths, so I think doing > that in qemu probably isn't a good idea. I agree It would nice to have some performance. This hcall is used when LSIs are involved, which is not really a common configuration. There are no OPAL calls involved. And we are duplicating code at the KVM level to retrigger the interrupt when the level is still asserted. I will benchmark the two options before making a choice. C. >> H_INT_SYNC and H_INT_RESET can not. >> >> H_INT_GET_OS_REPORTING_LINE and H_INT_SET_OS_REPORTING_LINE are not >> implemented. >> >> C. >> >