From: Babu Moger <babu.moger@amd.com>
To: <pbonzini@redhat.com>
Cc: <mtosatti@redhat.com>, <kvm@vger.kernel.org>, <mst@redhat.com>,
<marcel.apfelbaum@gmail.com>, <imammedo@redhat.com>,
<richard.henderson@linaro.org>, <yang.zhong@intel.com>,
<jing2.liu@intel.com>, <vkuznets@redhat.com>,
<qemu-devel@nongnu.org>, <michael.roth@amd.com>
Subject: [PATCH 3/5] target/i386: Add a couple of feature bits in 8000_0008_EBX
Date: Fri, 2 Dec 2022 13:47:24 -0600 [thread overview]
Message-ID: <167001044478.62456.9456560184804378623.stgit@bmoger-ubuntu> (raw)
In-Reply-To: <167001034454.62456.7111414518087569436.stgit@bmoger-ubuntu>
Add the following feature bits.
amd-psfd : Predictive Store Forwarding Disable:
PSF is a hardware-based micro-architectural optimization
designed to improve the performance of code execution by
predicting address dependencies between loads and stores.
While SSBD (Speculative Store Bypass Disable) disables both
PSF and speculative store bypass, PSFD only disables PSF.
PSFD may be desirable for the software which is concerned
with the speculative behavior of PSF but desires a smaller
performance impact than setting SSBD.
Depends on the following kernel commit:
b73a54321ad8 ("KVM: x86: Expose Predictive Store Forwarding Disable")
stibp-always-on :
Single Thread Indirect Branch Prediction mode has enhanced
performance and may be left always on.
The documentation for the features are available in the links below.
a. Processor Programming Reference (PPR) for AMD Family 19h Model 01h,
Revision B1 Processors
b. SECURITY ANALYSIS OF AMD PREDICTIVE STORE FORWARDING
Link: https://www.amd.com/system/files/documents/security-analysis-predictive-store-forwarding.pdf
Link: https://www.amd.com/system/files/TechDocs/55898_B1_pub_0.50.zip
Signed-off-by: Babu Moger <babu.moger@amd.com>
---
target/i386/cpu.c | 4 ++--
target/i386/cpu.h | 4 ++++
2 files changed, 6 insertions(+), 2 deletions(-)
diff --git a/target/i386/cpu.c b/target/i386/cpu.c
index 81918e10ba..b20e422b2e 100644
--- a/target/i386/cpu.c
+++ b/target/i386/cpu.c
@@ -909,10 +909,10 @@ FeatureWordInfo feature_word_info[FEATURE_WORDS] = {
NULL, NULL, NULL, NULL,
NULL, "wbnoinvd", NULL, NULL,
"ibpb", NULL, "ibrs", "amd-stibp",
- NULL, NULL, NULL, NULL,
+ NULL, "stibp-always-on", NULL, NULL,
NULL, NULL, NULL, NULL,
"amd-ssbd", "virt-ssbd", "amd-no-ssb", NULL,
- NULL, NULL, NULL, NULL,
+ "amd-psfd", NULL, NULL, NULL,
},
.cpuid = { .eax = 0x80000008, .reg = R_EBX, },
.tcg_features = 0,
diff --git a/target/i386/cpu.h b/target/i386/cpu.h
index d4bc19577a..8c65c92131 100644
--- a/target/i386/cpu.h
+++ b/target/i386/cpu.h
@@ -918,8 +918,12 @@ uint64_t x86_cpu_get_supported_feature_word(FeatureWord w,
#define CPUID_8000_0008_EBX_IBRS (1U << 14)
/* Single Thread Indirect Branch Predictors */
#define CPUID_8000_0008_EBX_STIBP (1U << 15)
+/* STIBP mode has enhanced performance and may be left always on */
+#define CPUID_8000_0008_EBX_STIBP_ALWAYS_ON (1U << 17)
/* Speculative Store Bypass Disable */
#define CPUID_8000_0008_EBX_AMD_SSBD (1U << 24)
+/* Predictive Store Forwarding Disable */
+#define CPUID_8000_0008_EBX_AMD_PSFD (1U << 28)
#define CPUID_XSAVE_XSAVEOPT (1U << 0)
#define CPUID_XSAVE_XSAVEC (1U << 1)
next prev parent reply other threads:[~2022-12-02 19:47 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-12-02 19:47 [PATCH 0/5] Update AMD EPYC CPU Models Babu Moger
2022-12-02 19:47 ` [PATCH 1/5] target/i386: allow versioned CPUs to specify new cache_info Babu Moger
2022-12-02 19:47 ` [PATCH 2/5] target/i386: Add new EPYC CPU versions with updated cache_info Babu Moger
2022-12-02 19:47 ` Babu Moger [this message]
2022-12-02 19:47 ` [PATCH 4/5] target/i386: Add feature bits for CPUID_Fn80000021_EAX Babu Moger
2022-12-02 19:47 ` [PATCH 5/5] target/i386: Add missing feature bits in EPYC-Milan model Babu Moger
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=167001044478.62456.9456560184804378623.stgit@bmoger-ubuntu \
--to=babu.moger@amd.com \
--cc=imammedo@redhat.com \
--cc=jing2.liu@intel.com \
--cc=kvm@vger.kernel.org \
--cc=marcel.apfelbaum@gmail.com \
--cc=michael.roth@amd.com \
--cc=mst@redhat.com \
--cc=mtosatti@redhat.com \
--cc=pbonzini@redhat.com \
--cc=qemu-devel@nongnu.org \
--cc=richard.henderson@linaro.org \
--cc=vkuznets@redhat.com \
--cc=yang.zhong@intel.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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.