[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

[PATCH 0/2] x86/svm: Add support for Bus Lock Threshold


  • To: <xen-devel@xxxxxxxxxxxxxxxxxxxx>
  • From: Alejandro Vallejo <alejandro.garciavallejo@xxxxxxx>
  • Date: Tue, 20 Jan 2026 10:53:48 +0100
  • Arc-authentication-results: i=1; mx.microsoft.com 1; spf=pass (sender ip is 165.204.84.17) smtp.rcpttodomain=lists.xenproject.org smtp.mailfrom=amd.com; dmarc=pass (p=quarantine sp=quarantine pct=100) action=none header.from=amd.com; dkim=none (message not signed); arc=none (0)
  • Arc-message-signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com; s=arcselector10001; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-AntiSpam-MessageData-ChunkCount:X-MS-Exchange-AntiSpam-MessageData-0:X-MS-Exchange-AntiSpam-MessageData-1; bh=xuIeWzyGiCnRAm9Kg6QG1cEl7K4jzzok7IMZLtDUxEs=; b=Wh7rF8J0LRGXxcGfKBRj9r5nhlXSnAwdlZEaRjo8IIcuGBkLnBBBOq1kSdKSGYOjIhNQDB/czShAVSMtwkbEgqpqsgb1WDCSxiYkRVD3r8yYa6IMpS5deEV6sSXu4kAGWAaHJcHg6SG8SKMSbAQ2w4FK1d8EL0Gk+HB5y5lCNA9s7lnWgpNgq3GavKsBvHdyvmLcmMoC92UXcpyS89KCl03ZCAedbt/shKmHtIHnm3ucIT9oUQ2LCgLIcBQhzkkX44ovLNXV0naAKrwCmMrD+nH6umP2EHoJWwCQjN6DZm75OPfdR4qblHp30P7lyZdpjlDMcGorFK20jCI+utcIQQ==
  • Arc-seal: i=1; a=rsa-sha256; s=arcselector10001; d=microsoft.com; cv=none; b=R/wkJMHnP+Fkb0e0iqE4EcWJ/cTDCDF5FTaePn09G7bcX7zOMxGOSpeGi1PKkcfS0Wm+Pn3T8yXpfCRtPW9holcuKATnHqSGmqRWSUd9I0k9pfpkQkkomMKfCE9IRdNQ9HyV1MD0CUq/CiEHm6Z0hl/1Fv2S7Ll6OUQqRLL9jsop69IET4clp5g6K90dRFeCll3bYfeHVW1ytMkhWalTezpR320ILkWk99AN3Pg7RkPAB89VFBLiAI2z3CRdksm9JOv29NETrs0kCR9ghb/d9ZvGg9F2T91rHjG7py0+ZzdMBZL17wOziccyYcZN3VOU/NXm9LSJ5zUVnUnnGmFp1g==
  • Cc: Alejandro Vallejo <alejandro.garciavallejo@xxxxxxx>, Jan Beulich <jbeulich@xxxxxxxx>, Andrew Cooper <andrew.cooper3@xxxxxxxxxx>, Roger Pau Monné <roger.pau@xxxxxxxxxx>, Jason Andryuk <jason.andryuk@xxxxxxx>, Stefano Stabellini <sstabellini@xxxxxxxxxx>
  • Delivery-date: Tue, 20 Jan 2026 09:54:28 +0000
  • List-id: Xen developer discussion <xen-devel.lists.xenproject.org>

Bus Locks are very costly and a VM left unchecked spamming instructions that
lock the memory bus (e.g: unaligned atomic CAS) makes system perf take a
nosedive. This patch is similar to BLD of VMX, but for SVM. It configures all
VMRUNs so they automatically exit at the first encounter of a buslock event,
effectively rate-limiting them.

Cheers,
Alejandro

Alejandro Vallejo (2):
  x86/svm: Add infrastructure for Bus Lock Threshold
  x86/svm: Intercept Bus Locks for HVM guests

 xen/arch/x86/hvm/svm/svm.c            |  5 +++++
 xen/arch/x86/hvm/svm/vmcb.c           |  6 ++++++
 xen/arch/x86/hvm/svm/vmcb.h           | 15 +++++++++++++--
 xen/arch/x86/include/asm/hvm/svm.h    |  2 ++
 xen/arch/x86/include/asm/perfc_defn.h |  2 +-
 5 files changed, 27 insertions(+), 3 deletions(-)


base-commit: 7b3e1b4e848d34c9a5b6634009959a7b9dd42104
-- 
2.43.0




 


Rackspace

Lists.xenproject.org is hosted with RackSpace, monitoring our
servers 24x7x365 and backed by RackSpace's Fanatical Support®.