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From: Peter Maydell <peter.maydell@linaro.org>
To: "Philippe Mathieu-Daudé" <f4bug@amsat.org>
Cc: QEMU Developers <qemu-devel@nongnu.org>,
	Paolo Bonzini <pbonzini@redhat.com>,
	kvm-devel <kvm@vger.kernel.org>, qemu-arm <qemu-arm@nongnu.org>,
	Richard Henderson <rth@twiddle.net>
Subject: Re: [RFC PATCH v2 6/7] accel/kvm: Let KVM_EXIT_MMIO return error
Date: Mon, 18 May 2020 17:01:28 +0100	[thread overview]
Message-ID: <CAFEAcA8tGgyYgHXT5LVGz675JMq6VWR56H++XO5gtTrcaZiDQQ@mail.gmail.com> (raw)
In-Reply-To: <20200518155308.15851-7-f4bug@amsat.org>

On Mon, 18 May 2020 at 16:53, Philippe Mathieu-Daudé <f4bug@amsat.org> wrote:
> Give the hypervisor a possibility to catch any error
> occuring during KVM_EXIT_MMIO.
> Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
> ---
> RFC because maybe we simply want to ignore this error instead

The "right" answer is that the kernel should enhance the KVM_EXIT_MMIO
API to allow userspace to say "sorry, you got a bus error on that
memory access the guest just tried" (which the kernel then has to
turn into an appropriate guest exception, or ignore, depending on
what the architecture requires.) You don't want to set ret to
non-zero here, because that will cause us to VM_STOP, and I
suspect that x86 at least is relying on the implict RAZ/WI
behaviour it currently gets.

-- PMM

  reply	other threads:[~2020-05-18 16:01 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-18 15:53 [PATCH v2 0/7] exec/memory: Enforce checking MemTxResult values Philippe Mathieu-Daudé
2020-05-18 15:53 ` [PATCH v2 1/7] exec: Let address_space_read/write_cached() propagate MemTxResult Philippe Mathieu-Daudé
2020-05-18 16:13   ` Peter Maydell
2020-05-18 15:53 ` [PATCH v2 2/7] exec: Propagate cpu_memory_rw_debug() error Philippe Mathieu-Daudé
2020-05-18 15:53 ` [PATCH v2 3/7] disas: Let disas::read_memory() handler return EIO on error Philippe Mathieu-Daudé
2020-05-18 15:53 ` [PATCH v2 4/7] hw/elf_ops: Do not ignore write failures when loading ELF Philippe Mathieu-Daudé
2020-05-19  7:58   ` Stefano Garzarella
2020-05-18 15:53 ` [PATCH v2 5/7] hw/arm/boot: Abort if set_kernel_args() fails Philippe Mathieu-Daudé
2020-05-18 16:08   ` Peter Maydell
2020-05-18 15:53 ` [RFC PATCH v2 6/7] accel/kvm: Let KVM_EXIT_MMIO return error Philippe Mathieu-Daudé
2020-05-18 16:01   ` Peter Maydell [this message]
2020-05-18 16:06     ` Philippe Mathieu-Daudé
2020-05-21 15:39     ` Paolo Bonzini
2020-05-21 15:45       ` Peter Maydell
2020-05-18 15:53 ` [RFC PATCH v2 7/7] hw/core/loader: Assert loading ROM regions succeeds at reset Philippe Mathieu-Daudé
2020-05-18 16:12   ` Peter Maydell
2020-05-18 16:25     ` Philippe Mathieu-Daudé
2020-05-21 15:40 ` [PATCH v2 0/7] exec/memory: Enforce checking MemTxResult values Paolo Bonzini

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