Advanced Micro Devices Corporation

Ati Technologies Ulc

Globalfoundries Inc.

David A Kaplan

Philip Ng

Marius Evers

Jeremy W Powell

Benjamin Charles Serebrin

Thomas R Woller

Tarun Nakra

Daniel Hopper

Mark Douglas Hummel

Rodney W Schmidt

John M King

Christopher D Bryant

Stephen Patrick Thompson

Nippon Harshadk Raval

Maggie Chan

Winthrop Wu

Jeff Rupley

Donald P Matthews, Jr

Joshua S Schiffman

Alexander J Branover

David S Christie

Paul J Moyer

Joel Howard Schopp

Ronald Perez

Debjit Das Sarma

Andrew William Lueck

James Ross Goodman

Anton Chernoff

Atchyuth Gorti

Paul Edward Kitchin

Jeffrey P Rupley, Ii

Richard A Relph

Jelena Ilic

Bill K Kwan

Creighton Eldridge

Leendert Van Doorn

Norm M Hack

Robert Krick

Nippon HarshadKumar Raval

Martin Kiernicki

Yoichi Shimokawa

William Thomas Morrison

Thomas Roy Woller

Leendert Van Doom

Joshua Schiffman

Bengamin Serebrin

A processing system includes a branch prediction structure storing information used to predict the outcome of a branch instruction. The processing system also includes a register storing a first identifier of a first process in response to the processing system changing from a first mode that allows the first process to modify the branch prediction structure to a second mode in which the branch prediction structure is not modifiable. The processing system further includes a processor core that selectively flushes the branch prediction structure based on a comparison of a second identifier of a second process and the first identifier stored in the register. The comparison is performed in response to the second process causing a change from the second mode to the first mode.

Protection against branch target buffer poisoning by a management layer

A processor supports managing DMA accesses, in secure fashion, at an IOMMU. The IOMMU is configured to ensure that, for a given DMA request issued by an I/O device and associated with a particular executing VM, the device is bound to the VM according to a specified security registration process, and the request is targeted to a region of memory that has been assigned to the VM. The IOMMU thus prevents a malicious entity from accessing confidential information of a VM via DMA requests.

Secure direct memory access

A processing system includes a processor core for processing instructions and a memory that stores a page table set including an extended page table having an extended page table entry storing extended page table attributes associated with a physical memory page. The system receives a virtual address and translates the virtual address to a physical address for the physical memory page. One or more extended page attributes associated with the physical memory page are retrieved from the extended page table entry based on the virtual address.

Paging hierarchies for extended page tables and extended page attributes

A computing system may implement a split random number generator that may use a random number generator to generate and store seed values in a memory for retrieval and use by one or more core processors to generate random numbers for secure processes within each core processor.

Split random number generator

Restricting peripheral device protocols in confidential compute architectures, the method including: receiving a first address translation request from a peripheral device supporting a first protocol, wherein the first protocol supports cache coherency between the peripheral device and a processor cache; determining that a confidential compute architecture is enabled; and providing, in response to the first address translation request, a response including an indication to the peripheral device to not use the first protocol.

Peripheral device protocols in confidential compute architectures

A virtualized computing environment is protected from a malicious hypervisor by restricting the hypervisor's access to one or more portions of an event (interrupt or exception) handling pathway of a guest virtual machine, wherein the guest virtual machine includes both a secure layer to manage security for the guest and one or more non-secure layers to handle event processing. The hypervisor is restricted from providing normal exception information to the guest virtual machine (referred to simply as a 'guest' herein), and instead is only permitted to provide an event signal to the secure layer of the guest. In response to the event signal, the secure layer of the guest accesses a specified region of memory for the event information, reviews the information, and provides the information to another, non-secure, layer of the guest for processing only if the event information complies with specified security protocols.

Hypervisor secure event handling at a processor

A load/store unit includes a first queue including a first entry for a store operation and a second queue including a second entry for a load operation that includes a return instruction that redirects a program flow to a location indicated by the return instruction. The load/store unit also includes a processor to determine that the store operation matches the load operation and selectively perform store-to-load forwarding (STLF) of a return address for the return instruction from the first entry to the second entry based on whether the store operation is associated with a call instruction. The load/store unit forwards the return address to the second entry in response to the store operation being associated with the call instruction. The load/store unit blocks forwarding until the store operation retires in response to the store operation not being associated with the call instruction.

Performing store-to-load forwarding of a return address for a return instruction

A processor core executes a first process. The first process is associated with a first context tag that is generated based on context information controlled by an operating system or hypervisor of the processing system. A branch prediction structure selectively provides the processor core with access to an entry in the branch prediction structure based on the first context tag and a second context tag associated with the entry. The branch prediction structure selectively provides the processor core with access to the entry in response to the first process executing a branch instruction. Tagging entries in the branch prediction structure reduces, or eliminates, aliasing between information used to predict branches taken by different processes at a branch instruction.

Context partitioning of branch prediction structures

A method includes establishing an isolated execution environment for executing a platform firmware operating mode subroutine in a platform firmware operating mode. In response to receiving an interrupt, the platform firmware operating mode subroutine is executed in the isolated execution environment. In response to detecting an attempted access of a hardware resource resulting from execution of the platform firmware operating mode subroutine, the attempted access is blocked when the attempted access violates a security policy.

Platform firmware isolation

Systems, apparatuses, and methods for implementing hypervisor post-write notification of processor state register modifications. A write to a state register of the processor may be detected during guest execution. In response to detecting the write to the state register, the processor may trigger microcode to perform the write and copy the new value of the register to a memory location prior to exiting the guest. The hypervisor may be notified of the update to the state register after it occurs, and the hypervisor may be prevented from modifying the value of the guest's state register. The hypervisor may terminate the guest if the update to the state register is unacceptable. Alternatively, the hypervisor may recommend an alternate value to the guest. If the guest agrees, the guest may set the state register to the alternate value recommended by the hypervisor when the guest resumes operation.

Hypervisor post-write notification of control and debug register updates

A subset of a set of architectural registers in a processing system is marked (or 'tainted') to indicate that speculative use of data in the subset of the architectural registers is constrained based on a taint handling policy. One or more speculation features supported by the processing system are disabled for the instruction so that the one or more speculation features cannot be used on data in the subset. In some cases, values of bits associated with the subset of architectural registers are modified to indicate that the subset is tainted. The taint handling policy can be indicated by values stored in a policy register. Taint markings are tracked in response to values stored in the tainted architectural registers being written to a memory or read from the memory.

Taint protection during speculative execution

A state of a first architectural register in a processing system is changed from a first state to a second state that indicates that the first architectural register is to be monitored during speculative execution. A second architectural register in the processing system is associated with a third state in response to the first architectural register being a source register for a memory load instruction that loads data from a memory into the second architectural register during speculative execution. Use of data in the second architectural register is constrained during speculative operations while the second architectural register is in the third state. In some cases, a 'set taint' instruction is executed to change the state of the first architectural register from the first state to the second state.

Selective use of taint protection during speculative execution

A processing system includes a plurality of input/output (I/O) devices representing a plurality of I/O resources. Each I/O resource has at least one corresponding memory mapped I/O (MMIO) address range. A trap handler detects a write request targeting a configuration space of an identified I/O resource of the plurality of I/O resources and, responsive to determining the identified I/O resource is a protected I/O resource, selectively blocks the write request from further processing by the processing system based on whether the write request would change an MMIO address decoding of the identified I/O resource.

Secured input/output resource protection

Overhead associated with verifying function return addresses to protect against security exploits is reduced by taking advantage of branch prediction mechanisms for predicting return addresses. More specifically, returning from a function includes popping a return address from a data stack. Well-known security exploits overwrite the return address on the data stack to hijack control flow. In some processors, a separate data structure referred to as a control stack is used to verify the data stack. When a return instruction is executed, the processor issues an exception if the return addresses on the control stack and the data stack are not identical. This overhead can be avoided by taking advantage of the return address stack, which is a data structure used by the branch predictor to predict return addresses. In most situations, if this prediction is correct, the above check does not need to occur, thus reducing the associated overhead.

Using return address predictor to speed up control stack return address verification

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David A Kaplan