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From: Claudio Carvalho <cclaudio@linux.ibm.com>
To: Paul Mackerras <paulus@ozlabs.org>
Cc: Madhavan Srinivasan <maddy@linux.vnet.ibm.com>,
	Michael Anderson <andmike@linux.ibm.com>,
	Ram Pai <linuxram@us.ibm.com>,
	kvm-ppc@vger.kernel.org, Bharata B Rao <bharata@linux.ibm.com>,
	linuxppc-dev@ozlabs.org,
	Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>,
	Anshuman Khandual <khandual@linux.vnet.ibm.com>
Subject: Re: [PATCH v3 3/9] powerpc: Introduce FW_FEATURE_ULTRAVISOR
Date: Mon, 1 Jul 2019 11:12:38 -0300	[thread overview]
Message-ID: <990dd9d3-441a-229c-a007-817d1dd856be@linux.ibm.com> (raw)
In-Reply-To: <20190615073600.GA24709@blackberry>


On 6/15/19 4:36 AM, Paul Mackerras wrote:
> On Thu, Jun 06, 2019 at 02:36:08PM -0300, Claudio Carvalho wrote:
>> This feature tells if the ultravisor firmware is available to handle
>> ucalls.
> Everything in this patch that depends on CONFIG_PPC_UV should just
> depend on CONFIG_PPC_POWERNV instead.  The reason is that every host
> kernel needs to be able to do the ultracall to set partition table
> entry 0, in case it ends up being run on a machine with an ultravisor.
> Otherwise we will have the situation where a host kernel may crash
> early in boot just because the machine it's booted on happens to have
> an ultravisor running.  The crash will be a particularly nasty one
> because it will happen before we have probed the machine type and
> initialized the console; therefore it will just look like the machine
> hangs for no discernable reason.

> We also need to think about how to provide a way for petitboot to know
> whether the kernel it is booting knows how to do a ucall to set its
> partition table entry.  One suggestion would be to modify
> vmlinux.lds.S to add a new PT_NOTE entry in the program header of the
> binary with (say) a 64-bit doubleword which is a bitmap indicating
> capabilities of the binary.  We would define the first bit as
> indicating that the kernel knows how to run under an ultravisor.
> When running under an ultravisor, petitboot could then look for the
> PT_NOTE and the ultravisor-capable bit in it, and if the PT_NOTE is
> not there or the bit is zero, put up a dialog warning the user that
> the kernel will probably crash early in boot, and asking for explicit
> confirmation that the user wants to proceed.


I just posted a separated RFC patch for the ELF note.

Thanks, Claudio.


>
> Paul.
>

  reply	other threads:[~2019-07-01 14:18 UTC|newest]

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-06-06 17:36 [PATCH v3 0/9] kvmppc: Paravirtualize KVM to support ultravisor Claudio Carvalho
2019-06-06 17:36 ` [PATCH v3 1/9] KVM: PPC: Ultravisor: Add PPC_UV config option Claudio Carvalho
2019-06-07 20:11   ` Leonardo Bras
2019-06-10 12:18     ` Claudio Carvalho
2019-06-06 17:36 ` [PATCH v3 2/9] KVM: PPC: Ultravisor: Introduce the MSR_S bit Claudio Carvalho
2019-06-06 17:36 ` [PATCH v3 3/9] powerpc: Introduce FW_FEATURE_ULTRAVISOR Claudio Carvalho
2019-06-15  7:36   ` Paul Mackerras
2019-07-01 14:12     ` Claudio Carvalho [this message]
2019-06-06 17:36 ` [PATCH v3 4/9] KVM: PPC: Ultravisor: Add generic ultravisor call handler Claudio Carvalho
2019-06-15  7:37   ` Paul Mackerras
2019-06-17  2:06   ` Paul Mackerras
2019-06-17 23:51     ` Ram Pai
2019-06-18 11:47     ` Segher Boessenkool
2019-06-18 15:25       ` Ram Pai
2019-06-06 17:36 ` [PATCH v3 5/9] KVM: PPC: Ultravisor: Use UV_WRITE_PATE ucall to register a PATE Claudio Carvalho
2019-06-15  7:38   ` Paul Mackerras
2019-06-06 17:36 ` [PATCH v3 6/9] KVM: PPC: Ultravisor: Restrict flush of the partition tlb cache Claudio Carvalho
2019-06-06 19:39   ` Murilo Opsfelder Araújo
2019-06-06 21:55     ` Paul Mackerras
2019-06-06 17:36 ` [PATCH v3 7/9] KVM: PPC: Ultravisor: Restrict LDBAR access Claudio Carvalho
2019-06-07  4:48   ` Madhavan Srinivasan
2019-06-07 12:34     ` Claudio Carvalho
2019-06-15  7:43   ` Paul Mackerras
2019-06-16  1:10     ` Ram Pai
2019-06-06 17:36 ` [PATCH v3 8/9] KVM: PPC: Ultravisor: Enter a secure guest Claudio Carvalho
2019-06-15  7:45   ` Paul Mackerras
2019-06-06 17:36 ` [PATCH v3 9/9] KVM: PPC: Ultravisor: Check for MSR_S during hv_reset_msr Claudio Carvalho
2019-06-15  7:47   ` Paul Mackerras

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