From: Andrew Scull <ascull@google.com>
To: George-Aurelian Popescu <georgepope@google.com>
Cc: maz@kernel.org, catalin.marinas@arm.com, will@kernel.org,
masahiroy@kernel.org, michal.lkml@markovi.net,
linux-arm-kernel@lists.infradead.org,
kvmarm@lists.cs.columbia.edu, linux-kernel@vger.kernel.org,
linux-kbuild@vger.kernel.org, clang-built-linux@googlegroups.com,
james.morse@arm.com, julien.thierry.kdev@gmail.com,
suzuki.poulose@arm.com, natechancellor@gmail.com,
ndesaulniers@google.com, dbrazdil@google.com, broonie@kernel.org,
maskray@google.com, keescook@chromium.org,
akpm@linux-foundation.org, dvyukov@google.com, elver@google.com,
tglx@linutronix.de, arnd@arndb.de
Subject: Re: [PATCH 03/14] KVM: arm64: Add support for creating and checking a logging buffer inside hyp/nVHE
Date: Thu, 1 Oct 2020 11:07:50 +0100 [thread overview]
Message-ID: <20201001100750.GA541087@google.com> (raw)
In-Reply-To: <20200914172750.852684-4-georgepope@google.com>
On Mon, Sep 14, 2020 at 05:27:39PM +0000, George-Aurelian Popescu wrote:
> From: George Popescu <georgepope@google.com>
>
> Share a buffer between the kernel and the hyp/nVHE code by using the
> macros from kvm_debug_buffer.h.
>
> The buffer is composed of a writing index and a statically allocated
> array. The writing index counts how many elements have been written inside
> the buffer and should be set to zero whenever the code goes back to
> EL2 with the clear_kvm_debug_buffer macro.
>
> To avoid consistency problems the buffer is defined per_cpu and is designed
> to be read-only from the kernel perspective.
>
> Check if there is any logging data from hyp/nVHE code.
>
> Every time when the state returns back to the kernel after an hvc call,
> the __kvm_arm_check_debug_buffer macro checks if there is any data inside
> one of the predefined buffers.
>
> Signed-off-by: George Popescu <georgepope@google.com>
> ---
> arch/arm64/include/asm/kvm_debug_buffer.h | 34 +++++++++++++++++++++++
> arch/arm64/include/asm/kvm_host.h | 6 ++++
> arch/arm64/kvm/hyp/hyp-entry.S | 2 +-
> 3 files changed, 41 insertions(+), 1 deletion(-)
> create mode 100644 arch/arm64/include/asm/kvm_debug_buffer.h
>
> diff --git a/arch/arm64/include/asm/kvm_debug_buffer.h b/arch/arm64/include/asm/kvm_debug_buffer.h
> new file mode 100644
> index 000000000000..30c9b0b1a7bf
> --- /dev/null
> +++ b/arch/arm64/include/asm/kvm_debug_buffer.h
> @@ -0,0 +1,34 @@
> +/* SPDX-License-Identifier: GPL-2.0-only */
> +/*
> + * Copyright 2020 Google LLC
> + * Author: George Popescu <georgepope@google.com>
> + */
> +#ifndef __ASSEMBLY__
> +
> +#include <linux/percpu-defs.h>
> +#include <asm/kvm_asm.h>
> +
> +#ifdef __KVM_NVHE_HYPERVISOR__
> +#define DEFINE_KVM_DEBUG_BUFFER(type_name, buff_name, size) \
> + DEFINE_PER_CPU(type_name, buff_name)[(size)]; \
> + DEFINE_PER_CPU(unsigned long, buff_name##_wr_ind) = 0
> +
> +#define DECLARE_KVM_DEBUG_BUFFER(type_name, buff_name, size) \
> + DECLARE_PER_CPU(type_name, buff_name)[(size)]; \
> + DECLARE_PER_CPU(unsigned long, buff_name##_wr_ind)
> +
> +#else
> +
> +#define DECLARE_KVM_DEBUG_BUFFER(type_name, buff_name, size) \
> + DECLARE_PER_CPU(type_name, kvm_nvhe_sym(buff_name))[(size)]; \
> + DECLARE_PER_CPU(unsigned long, kvm_nvhe_sym(buff_name##_wr_ind))
> +#endif //__KVM_NVHE_HYPERVISOR__
nit: comment style, here and below
> +
> +#else
> +
> +.macro clear_kvm_debug_buffer sym tmp1, tmp2, tmp3
> + mov \tmp1, 0
> + hyp_str_this_cpu \sym, \tmp1, \tmp2, \tmp3
> +.endm
Can you can use xzr (zero register) directly rather than moving the
constant 0 into a temporary?
hyp_str_this_cpu \sym, xzr, \tmp1, \tmp2
> +
> +#endif // __ASSEMBLY__
> diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
> index 905c2b87e05a..adc8957e9321 100644
> --- a/arch/arm64/include/asm/kvm_host.h
> +++ b/arch/arm64/include/asm/kvm_host.h
> @@ -494,6 +494,10 @@ u64 __kvm_call_hyp(void *hypfn, ...);
> __kvm_call_hyp(kvm_ksym_ref_nvhe(f), ##__VA_ARGS__); \
> })
>
> +#define __kvm_arm_check_debug_buffer() \
> +{ \
> +}
> +
> /*
> * The couple of isb() below are there to guarantee the same behaviour
> * on VHE as on !VHE, where the eret to EL1 acts as a context
> @@ -506,6 +510,7 @@ u64 __kvm_call_hyp(void *hypfn, ...);
> isb(); \
> } else { \
> kvm_call_hyp_nvhe(f, ##__VA_ARGS__); \
> + __kvm_arm_check_debug_buffer(); \
> } \
> } while(0)
>
> @@ -518,6 +523,7 @@ u64 __kvm_call_hyp(void *hypfn, ...);
> isb(); \
> } else { \
> ret = kvm_call_hyp_nvhe_ret(f, ##__VA_ARGS__); \
> + __kvm_arm_check_debug_buffer(); \
As Will was pointing out earlier, does the checking need to have
preemption disabled in case there is another call into hyp that corrupts
the buffer while it is being checked?
> } \
> \
> ret; \
> diff --git a/arch/arm64/kvm/hyp/hyp-entry.S b/arch/arm64/kvm/hyp/hyp-entry.S
> index 46b4dab933d0..8df0082b9ccf 100644
> --- a/arch/arm64/kvm/hyp/hyp-entry.S
> +++ b/arch/arm64/kvm/hyp/hyp-entry.S
> @@ -68,7 +68,7 @@ el1_sync: // Guest trapped into EL2
> cbnz x1, el1_hvc_guest // called HVC
>
> /* Here, we're pretty sure the host called HVC. */
> - ldp x0, x1, [sp], #16
> + ldp x0, x1, [sp], #16
Is this a whitespace change? Maybe drop from this patch if it isn't
related.
>
> /* Check for a stub HVC call */
> cmp x0, #HVC_STUB_HCALL_NR
> --
> 2.28.0.618.gf4bc123cb7-goog
>
next prev parent reply other threads:[~2020-10-01 10:08 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-14 17:27 [PATCH 00/14] UBSan Enablement for hyp/nVHE code George-Aurelian Popescu
2020-09-14 17:27 ` [PATCH 01/14] KVM: arm64: Enable UBSan instrumentation in nVHE hyp code George-Aurelian Popescu
2020-09-14 17:27 ` [PATCH 02/14] KVM: arm64: Define a macro for storing a value inside a per_cpu variable George-Aurelian Popescu
2020-09-14 17:27 ` [PATCH 03/14] KVM: arm64: Add support for creating and checking a logging buffer inside hyp/nVHE George-Aurelian Popescu
2020-10-01 10:07 ` Andrew Scull [this message]
2020-09-14 17:27 ` [PATCH 04/14] KVM: arm64: Add support for buffer usage George-Aurelian Popescu
2020-09-14 17:27 ` [PATCH 05/14] KVM: arm64: Define a buffer that can pass UBSan data from hyp/nVHE to kernel George-Aurelian Popescu
2020-09-15 13:25 ` George Popescu
2020-10-01 10:51 ` Andrew Scull
2020-09-14 17:27 ` [PATCH 06/14] Fix CFLAGS for UBSAN_BOUNDS on Clang George-Aurelian Popescu
2020-09-14 21:17 ` Nick Desaulniers
2020-09-14 22:13 ` Kees Cook
2020-09-15 10:24 ` George Popescu
2020-09-15 11:18 ` Marco Elver
2020-09-15 12:01 ` George Popescu
2020-09-15 17:32 ` Marco Elver
2020-09-16 7:40 ` George Popescu
2020-09-16 8:32 ` Marco Elver
[not found] ` <20200916121401.GA3362356@google.com>
2020-09-16 13:40 ` Marco Elver
2020-09-17 6:37 ` Marco Elver
2020-09-17 11:35 ` George Popescu
2020-09-17 22:21 ` Kees Cook
2020-09-17 22:17 ` Kees Cook
2020-09-14 17:27 ` [PATCH 07/14] KVM: arm64: Enable UBSAN_BOUNDS for the both the kernel and hyp/nVHE George-Aurelian Popescu
2020-10-01 10:57 ` Andrew Scull
2020-09-14 17:27 ` [PATCH 08/14] KVM: arm64: Enable UBsan check for unreachable code inside hyp/nVHE code George-Aurelian Popescu
2020-09-14 17:27 ` [PATCH 09/14] KVM: arm64: Enable shift out of bounds undefined behaviour check for hyp/nVHE George-Aurelian Popescu
2020-09-14 17:27 ` [PATCH 10/14] KVM: arm64: __ubsan_handle_load_invalid_value hyp/nVHE implementation George-Aurelian Popescu
2020-09-14 17:27 ` [PATCH 11/14] KVM: arm64: Detect type mismatch undefined behaviour from hyp/nVHE code George-Aurelian Popescu
2020-09-14 17:27 ` [PATCH 12/14] KVM: arm64: Detect arithmetic overflow is inside hyp/nVHE George-Aurelian Popescu
2020-09-14 17:27 ` [PATCH 13/14] KVM: arm64: Enable the CONFIG_TEST UBSan for PKVM George-Aurelian Popescu
2020-09-14 17:27 ` [PATCH 14/14] DO NOT MERGE: Enable configs to test the patch series George-Aurelian Popescu
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20201001100750.GA541087@google.com \
--to=ascull@google.com \
--cc=akpm@linux-foundation.org \
--cc=arnd@arndb.de \
--cc=broonie@kernel.org \
--cc=catalin.marinas@arm.com \
--cc=clang-built-linux@googlegroups.com \
--cc=dbrazdil@google.com \
--cc=dvyukov@google.com \
--cc=elver@google.com \
--cc=georgepope@google.com \
--cc=james.morse@arm.com \
--cc=julien.thierry.kdev@gmail.com \
--cc=keescook@chromium.org \
--cc=kvmarm@lists.cs.columbia.edu \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kbuild@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=masahiroy@kernel.org \
--cc=maskray@google.com \
--cc=maz@kernel.org \
--cc=michal.lkml@markovi.net \
--cc=natechancellor@gmail.com \
--cc=ndesaulniers@google.com \
--cc=suzuki.poulose@arm.com \
--cc=tglx@linutronix.de \
--cc=will@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).