From: David Laight <David.Laight@ACULAB.COM>
To: 'Jordan Niethe' <jniethe5@gmail.com>,
"linuxppc-dev@lists.ozlabs.org" <linuxppc-dev@lists.ozlabs.org>
Cc: "mikey@neuling.org" <mikey@neuling.org>,
"sbhat@linux.ibm.com" <sbhat@linux.ibm.com>,
"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
"amachhiw@linux.vnet.ibm.com" <amachhiw@linux.vnet.ibm.com>,
"gautam@linux.ibm.com" <gautam@linux.ibm.com>,
"npiggin@gmail.com" <npiggin@gmail.com>,
"kvm-ppc@vger.kernel.org" <kvm-ppc@vger.kernel.org>,
"vaibhav@linux.ibm.com" <vaibhav@linux.ibm.com>,
"kconsul@linux.vnet.ibm.com" <kconsul@linux.vnet.ibm.com>
Subject: RE: [PATCH v3 4/6] KVM: PPC: Book3s HV: Hold LPIDs in an unsigned long
Date: Mon, 14 Aug 2023 08:15:41 +0000 [thread overview]
Message-ID: <014488c6d90446f38154a2f7645aa053@AcuMS.aculab.com> (raw)
In-Reply-To: <20230807014553.1168699-5-jniethe5@gmail.com>
From: Jordan Niethe
> Sent: 07 August 2023 02:46
>
> The LPID register is 32 bits long. The host keeps the lpids for each
> guest in an unsigned word struct kvm_arch. Currently, LPIDs are already
> limited by mmu_lpid_bits and KVM_MAX_NESTED_GUESTS_SHIFT.
>
> The nestedv2 API returns a 64 bit "Guest ID" to be used be the L1 host
> for each L2 guest. This value is used as an lpid, e.g. it is the
> parameter used by H_RPT_INVALIDATE. To minimize needless special casing
> it makes sense to keep this "Guest ID" in struct kvm_arch::lpid.
>
> This means that struct kvm_arch::lpid is too small so prepare for this
> and make it an unsigned long. This is not a problem for the KVM-HV and
> nestedv1 cases as their lpid values are already limited to valid ranges
> so in those contexts the lpid can be used as an unsigned word safely as
> needed.
Shouldn't it be changed to u64?
David
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Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)
next prev parent reply other threads:[~2023-08-14 8:16 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-08-07 1:45 [PATCH v3 0/6] KVM: PPC: Nested APIv2 guest support Jordan Niethe
2023-08-07 1:45 ` [PATCH v3 1/6] KVM: PPC: Use getters and setters for vcpu register state Jordan Niethe
2023-08-14 8:08 ` Nicholas Piggin
2023-08-16 3:11 ` Jordan Niethe
2023-08-17 3:25 ` Michael Ellerman
2023-08-07 1:45 ` [PATCH v3 2/6] KVM: PPC: Rename accessor generator macros Jordan Niethe
2023-08-14 8:27 ` Nicholas Piggin
2023-08-16 3:20 ` Jordan Niethe
2023-08-07 1:45 ` [PATCH v3 3/6] KVM: PPC: Add helper library for Guest State Buffers Jordan Niethe
2023-08-07 1:45 ` [PATCH v3 4/6] KVM: PPC: Book3s HV: Hold LPIDs in an unsigned long Jordan Niethe
2023-08-14 8:12 ` Nicholas Piggin
2023-08-15 10:45 ` Michael Ellerman
2023-08-16 3:21 ` Jordan Niethe
2023-08-16 3:14 ` Jordan Niethe
2023-08-14 8:15 ` David Laight [this message]
2023-08-16 3:19 ` Jordan Niethe
2023-08-17 12:21 ` Michael Ellerman
2023-08-07 1:45 ` [PATCH v3 5/6] KVM: PPC: Add support for nestedv2 guests Jordan Niethe
2023-08-17 4:19 ` Michael Ellerman
2023-08-17 12:23 ` Michael Ellerman
2023-08-07 1:45 ` [PATCH v3 6/6] docs: powerpc: Document nested KVM on POWER Jordan Niethe
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