From: James Morse <james.morse@arm.com>
To: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Marc Zyngier <maz@kernel.org>,
linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
Sami Tolvanen <samitolvanen@google.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>,
kvmarm <kvmarm@lists.cs.columbia.edu>
Subject: Re: [PATCH 0/3] KVM: arm64: Ask the compiler to __always_inline functions used by KVM at HYP
Date: Thu, 20 Feb 2020 17:33:18 +0000 [thread overview]
Message-ID: <1ecedad2-1b3e-0d37-42e8-7022ac5a8370@arm.com> (raw)
In-Reply-To: <CAKv+Gu-tPOWyxjsKrL-auC=ZxeNJPgAPyQ2rBd9S8sgMbb=r_w@mail.gmail.com>
Hi Ard,
On 20/02/2020 17:04, Ard Biesheuvel wrote:
> On Thu, 20 Feb 2020 at 17:58, James Morse <james.morse@arm.com> wrote:
>> It turns out KVM relies on the inline hint being honoured by the compiler
>> in quite a few more places than expected. Something about the Shadow Call
>> Stack support[0] causes the compiler to avoid inline-ing and to place
>> these functions outside the __hyp_text. This ruins KVM's day.
>>
>> Add the simon-says __always_inline annotation to all the static
>> inlines that KVM calls from HYP code.
> This isn't quite as yuck as I expected, fortunately, but it does beg
> the question whether we shouldn't simply map the entire kernel at EL2
> instead?
If the kernel is big enough to need internal veneers (the 128M range?), these would
certainly go horribly wrong because its running somewhere other than the relocation-time
address. We would need a way of telling the linker to keep the bits of KVM close together...
Thanks,
James
_______________________________________________
kvmarm mailing list
kvmarm@lists.cs.columbia.edu
https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
WARNING: multiple messages have this Message-ID (diff)
From: James Morse <james.morse@arm.com>
To: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Suzuki K Poulose <suzuki.poulose@arm.com>,
Marc Zyngier <maz@kernel.org>,
linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
Sami Tolvanen <samitolvanen@google.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>,
kvmarm <kvmarm@lists.cs.columbia.edu>,
Julien Thierry <julien.thierry.kdev@gmail.com>
Subject: Re: [PATCH 0/3] KVM: arm64: Ask the compiler to __always_inline functions used by KVM at HYP
Date: Thu, 20 Feb 2020 17:33:18 +0000 [thread overview]
Message-ID: <1ecedad2-1b3e-0d37-42e8-7022ac5a8370@arm.com> (raw)
In-Reply-To: <CAKv+Gu-tPOWyxjsKrL-auC=ZxeNJPgAPyQ2rBd9S8sgMbb=r_w@mail.gmail.com>
Hi Ard,
On 20/02/2020 17:04, Ard Biesheuvel wrote:
> On Thu, 20 Feb 2020 at 17:58, James Morse <james.morse@arm.com> wrote:
>> It turns out KVM relies on the inline hint being honoured by the compiler
>> in quite a few more places than expected. Something about the Shadow Call
>> Stack support[0] causes the compiler to avoid inline-ing and to place
>> these functions outside the __hyp_text. This ruins KVM's day.
>>
>> Add the simon-says __always_inline annotation to all the static
>> inlines that KVM calls from HYP code.
> This isn't quite as yuck as I expected, fortunately, but it does beg
> the question whether we shouldn't simply map the entire kernel at EL2
> instead?
If the kernel is big enough to need internal veneers (the 128M range?), these would
certainly go horribly wrong because its running somewhere other than the relocation-time
address. We would need a way of telling the linker to keep the bits of KVM close together...
Thanks,
James
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2020-02-20 17:33 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-20 16:58 [PATCH 0/3] KVM: arm64: Ask the compiler to __always_inline functions used by KVM at HYP James Morse
2020-02-20 16:58 ` James Morse
2020-02-20 16:58 ` [PATCH 1/3] KVM: arm64: Ask the compiler to __always_inline functions used " James Morse
2020-02-20 16:58 ` James Morse
2020-02-20 16:58 ` [PATCH 2/3] KVM: arm64: define our own swab32() to avoid a uapi static inline James Morse
2020-02-20 16:58 ` James Morse
2020-02-20 16:58 ` [PATCH 3/3] arm64: Ask the compiler to __always_inline functions used by KVM at HYP James Morse
2020-02-20 16:58 ` James Morse
2020-02-21 13:13 ` Will Deacon
2020-02-21 13:13 ` Will Deacon
2020-02-21 13:22 ` Ard Biesheuvel
2020-02-21 13:22 ` Ard Biesheuvel
2020-02-20 17:04 ` [PATCH 0/3] KVM: " Ard Biesheuvel
2020-02-20 17:04 ` Ard Biesheuvel
2020-02-20 17:33 ` James Morse [this message]
2020-02-20 17:33 ` James Morse
2020-02-20 17:35 ` Ard Biesheuvel
2020-02-20 17:35 ` Ard Biesheuvel
2020-02-21 12:55 ` Marc Zyngier
2020-02-21 12:55 ` Marc Zyngier
2020-02-21 14:57 ` James Morse
2020-02-21 14:57 ` James Morse
2020-02-21 16:38 ` Marc Zyngier
2020-02-21 16:38 ` Marc Zyngier
2020-02-24 13:22 ` Andrew Jones
2020-02-24 13:22 ` Andrew Jones
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