From: Andrew Murray <andrew.murray@arm.com>
To: Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>, Marc Zyngier <maz@kernel.org>,
Mark Rutland <mark.rutland@arm.com>
Cc: kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org
Subject: [PATCH v4 1/3] arm64: cpufeature: Extract capped fields
Date: Thu, 23 Jan 2020 11:58:50 +0000 [thread overview]
Message-ID: <20200123115852.55595-2-andrew.murray@arm.com> (raw)
In-Reply-To: <20200123115852.55595-1-andrew.murray@arm.com>
When emulating ID registers there is often a need to cap the version
bits of a feature such that the guest will not use features that do
not yet exist.
Let's add a helper that extracts a field and caps the version to a
given value.
Signed-off-by: Andrew Murray <andrew.murray@arm.com>
---
arch/arm64/include/asm/cpufeature.h | 16 ++++++++++++++++
1 file changed, 16 insertions(+)
diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h
index 4261d55e8506..1462fd1101e3 100644
--- a/arch/arm64/include/asm/cpufeature.h
+++ b/arch/arm64/include/asm/cpufeature.h
@@ -447,6 +447,22 @@ cpuid_feature_extract_unsigned_field(u64 features, int field)
return cpuid_feature_extract_unsigned_field_width(features, field, 4);
}
+static inline u64 __attribute_const__
+cpuid_feature_cap_signed_field_width(u64 features, int field, int width,
+ s64 cap)
+{
+ s64 val = cpuid_feature_extract_signed_field_width(features, field,
+ width);
+ u64 mask = GENMASK_ULL(field + width - 1, field);
+
+ if (val > cap) {
+ features &= ~mask;
+ features |= (cap << field) & mask;
+ }
+
+ return features;
+}
+
static inline u64 arm64_ftr_mask(const struct arm64_ftr_bits *ftrp)
{
return (u64)GENMASK(ftrp->shift + ftrp->width - 1, ftrp->shift);
--
2.21.0
_______________________________________________
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:[~2020-01-23 11:59 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-23 11:58 [PATCH v4 0/3] arm64: perf: Add support for ARMv8.5-PMU 64-bit counters Andrew Murray
2020-01-23 11:58 ` Andrew Murray [this message]
2020-01-23 11:58 ` [PATCH v4 2/3] KVM: arm64: limit PMU version to ARMv8.4 Andrew Murray
2020-01-23 17:04 ` Marc Zyngier
2020-01-23 11:58 ` [PATCH v4 3/3] arm64: perf: Add support for ARMv8.5-PMU 64-bit counters Andrew Murray
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=20200123115852.55595-2-andrew.murray@arm.com \
--to=andrew.murray@arm.com \
--cc=catalin.marinas@arm.com \
--cc=kvmarm@lists.cs.columbia.edu \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=mark.rutland@arm.com \
--cc=maz@kernel.org \
--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).