From: Michael Ellerman <patch-notifications@ellerman.id.au>
To: Alexey Kardashevskiy <aik@ozlabs.ru>, linuxppc-dev@lists.ozlabs.org
Cc: Frederic Barrat <fbarrat@linux.ibm.com>,
kvm-ppc@vger.kernel.org, Fabiano Rosas <farosas@linux.ibm.com>
Subject: Re: [PATCH kernel v2] KVM: PPC: Book3s: Retire H_PUT_TCE/etc real mode handlers
Date: Tue, 24 May 2022 10:51:51 +0000 [thread overview]
Message-ID: <165338951112.1711920.752815379112806107.b4-ty@ellerman.id.au> (raw)
In-Reply-To: <20220506053755.3820702-1-aik@ozlabs.ru>
On Fri, 6 May 2022 15:37:55 +1000, Alexey Kardashevskiy wrote:
> LoPAPR defines guest visible IOMMU with hypercalls to use it -
> H_PUT_TCE/etc. Implemented first on POWER7 where hypercalls would trap
> in the KVM in the real mode (with MMU off). The problem with the real mode
> is some memory is not available and some API usage crashed the host but
> enabling MMU was an expensive operation.
>
> The problems with the real mode handlers are:
> 1. Occasionally these cannot complete the request so the code is
> copied+modified to work in the virtual mode, very little is shared;
> 2. The real mode handlers have to be linked into vmlinux to work;
> 3. An exception in real mode immediately reboots the machine.
>
> [...]
Applied to powerpc/topic/ppc-kvm.
[1/1] KVM: PPC: Book3s: Retire H_PUT_TCE/etc real mode handlers
https://git.kernel.org/powerpc/c/cad32d9d42e8e6a659786f8a730b221a9fbee227
cheers
prev parent reply other threads:[~2022-05-24 10:51 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-05-06 5:37 [PATCH kernel v2] KVM: PPC: Book3s: Retire H_PUT_TCE/etc real mode handlers Alexey Kardashevskiy
2022-05-24 10:51 ` Michael Ellerman [this message]
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