From: Marc Zyngier <maz@kernel.org>
To: James Clark <james.clark@arm.com>
Cc: coresight@lists.linaro.org, linux-arm-kernel@lists.infradead.org,
kvmarm@lists.linux.dev, suzuki.poulose@arm.com, acme@kernel.org,
oliver.upton@linux.dev, broonie@kernel.org,
James Morse <james.morse@arm.com>,
Zenghui Yu <yuzenghui@huawei.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>, Mike Leach <mike.leach@linaro.org>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
Anshuman Khandual <anshuman.khandual@arm.com>,
Miguel Luis <miguel.luis@oracle.com>,
Joey Gouly <joey.gouly@arm.com>, Ard Biesheuvel <ardb@kernel.org>,
Javier Martinez Canillas <javierm@redhat.com>,
Mark Rutland <mark.rutland@arm.com>,
Arnd Bergmann <arnd@arndb.de>,
Andrew Walbran <qwandor@google.com>,
Vincent Donnefort <vdonnefort@google.com>,
Ryan Roberts <ryan.roberts@arm.com>,
Fuad Tabba <tabba@google.com>,
Jing Zhang <jingzhangos@google.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v6 7/8] arm64: KVM: Write TRFCR value on guest switch with nVHE
Date: Mon, 26 Feb 2024 18:26:53 +0000 [thread overview]
Message-ID: <868r372iaa.wl-maz@kernel.org> (raw)
In-Reply-To: <20240226113044.228403-8-james.clark@arm.com>
On Mon, 26 Feb 2024 11:30:35 +0000,
James Clark <james.clark@arm.com> wrote:
>
> The guest value for TRFCR requested by the Coresight driver is saved in
> kvm_guest_trfcr. On guest switch this value needs to be written to
> the register. Currently TRFCR is only modified when we want to disable
> trace completely in guests due to an issue with TRBE. Expand the
> __debug_save_trace() function to always write to the register if a
> different value for guests is required, but also keep the existing TRBE
> disable behavior if that's required.
>
> In pKVM, the kvm_guest_trfcr can't be read and the host isn't trusted,
> so always disable trace.
>
> __debug_restore_trace() now has to restore unconditionally, because even
> a value of 0 needs to be written to overwrite whatever was set for the
> guest.
>
> Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
> Signed-off-by: James Clark <james.clark@arm.com>
> ---
> arch/arm64/kvm/hyp/nvhe/debug-sr.c | 53 +++++++++++++++++-------------
> 1 file changed, 31 insertions(+), 22 deletions(-)
>
> diff --git a/arch/arm64/kvm/hyp/nvhe/debug-sr.c b/arch/arm64/kvm/hyp/nvhe/debug-sr.c
> index 4558c02eb352..3adac2e01908 100644
> --- a/arch/arm64/kvm/hyp/nvhe/debug-sr.c
> +++ b/arch/arm64/kvm/hyp/nvhe/debug-sr.c
> @@ -51,30 +51,39 @@ static void __debug_restore_spe(u64 pmscr_el1)
> write_sysreg_s(pmscr_el1, SYS_PMSCR_EL1);
> }
>
> -static void __debug_save_trace(u64 *trfcr_el1)
> +static void __debug_save_trace(struct kvm_vcpu *vcpu)
> {
> - *trfcr_el1 = 0;
> -
> - /* Check if the TRBE is enabled */
> - if (!(read_sysreg_s(SYS_TRBLIMITR_EL1) & TRBLIMITR_EL1_E))
> - return;
> - /*
> - * Prohibit trace generation while we are in guest.
> - * Since access to TRFCR_EL1 is trapped, the guest can't
> - * modify the filtering set by the host.
> - */
> - *trfcr_el1 = read_sysreg_s(SYS_TRFCR_EL1);
> - write_sysreg_s(0, SYS_TRFCR_EL1);
> - isb();
> - /* Drain the trace buffer to memory */
> - tsb_csync();
> + u64 host_trfcr_el1 = read_sysreg_s(SYS_TRFCR_EL1);
Ah, and on top of that, this is already broken with hVHE.
I'll send a patch.
M.
--
Without deviation from the norm, progress is not possible.
next prev parent reply other threads:[~2024-02-26 18:26 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-02-26 11:30 [PATCH v6 0/8] kvm/coresight: Support exclude guest and exclude host James Clark
2024-02-26 11:30 ` [PATCH v6 1/8] arm64: KVM: Fix renamed function in comment James Clark
2024-02-26 11:30 ` [PATCH v6 2/8] arm64/sysreg: Add a comment that the sysreg file should be sorted James Clark
2024-02-26 13:19 ` Mark Brown
2024-02-26 11:30 ` [PATCH v6 3/8] tools: arm64: Update sysreg.h header files James Clark
2024-02-26 11:30 ` [PATCH v6 4/8] arm64/sysreg/tools: Move TRFCR definitions to sysreg James Clark
2024-02-26 13:21 ` Mark Brown
2024-02-26 11:30 ` [PATCH v6 5/8] arm64: KVM: Add iflag for FEAT_TRF James Clark
2024-02-26 13:35 ` Marc Zyngier
2024-02-26 15:41 ` James Clark
2024-02-26 18:03 ` Marc Zyngier
2024-02-26 11:30 ` [PATCH v6 6/8] arm64: KVM: Add interface to set guest value for TRFCR register James Clark
2024-02-26 15:01 ` Marc Zyngier
2024-02-26 11:30 ` [PATCH v6 7/8] arm64: KVM: Write TRFCR value on guest switch with nVHE James Clark
2024-02-26 17:50 ` Marc Zyngier
2024-02-26 18:26 ` Marc Zyngier [this message]
2024-02-26 11:30 ` [PATCH v6 8/8] coresight: Pass guest TRFCR value to KVM James Clark
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=868r372iaa.wl-maz@kernel.org \
--to=maz@kernel.org \
--cc=acme@kernel.org \
--cc=alexander.shishkin@linux.intel.com \
--cc=anshuman.khandual@arm.com \
--cc=ardb@kernel.org \
--cc=arnd@arndb.de \
--cc=broonie@kernel.org \
--cc=catalin.marinas@arm.com \
--cc=coresight@lists.linaro.org \
--cc=james.clark@arm.com \
--cc=james.morse@arm.com \
--cc=javierm@redhat.com \
--cc=jingzhangos@google.com \
--cc=joey.gouly@arm.com \
--cc=kvmarm@lists.linux.dev \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mark.rutland@arm.com \
--cc=miguel.luis@oracle.com \
--cc=mike.leach@linaro.org \
--cc=oliver.upton@linux.dev \
--cc=qwandor@google.com \
--cc=ryan.roberts@arm.com \
--cc=suzuki.poulose@arm.com \
--cc=tabba@google.com \
--cc=vdonnefort@google.com \
--cc=will@kernel.org \
--cc=yuzenghui@huawei.com \
/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).