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audk/UefiCpuPkg/CpuIo2Dxe/X64/IoFifo.asm

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UefiCpuPkg: CpuIo2Dxe: optimize FIFO reads and writes of IO ports * Short description: The CpuIoServiceRead() and CpuIoServiceWrite() functions transfer data between memory and IO ports with individual Io(Read|Write)(8|16|32) function calls, each in an appropriately set up loop. On the Ia32 and X64 platforms however, FIFO reads and writes can be optimized, by coding them in assembly, and delegating the loop to the CPU, with the REP prefix. On KVM virtualization hosts, this difference has a huge performance impact: if the loop is open-coded, then the virtual machine traps to the hypervisor on every single UINT8 / UINT16 / UINT32 transfer, whereas with the REP prefix, KVM can transfer up to a page of data per VM trap. This is especially noticeable with IDE PIO transfers, where all the data are squeezed through IO ports. * Long description: The RootBridgeIoIoRW() function in PcAtChipsetPkg/PciHostBridgeDxe/PciRootBridgeIo.c used to have the exact same IO port acces optimization, dating back verbatim to commit 1fd376d9792: PcAtChipsetPkg/PciHostBridgeDxe: Improve KVM FIFO I/O read/write performance OvmfPkg cloned the "PcAtChipsetPkg/PciHostBridgeDxe" driver (for unrelated reasons), and inherited the optimization from PcAtChipsetPkg. The "PcAtChipsetPkg/PciHostBridgeDxe" driver was ultimately removed in commit 111d79db47: PcAtChipsetPkg/PciHostBridge: Remove PciHostBridge driver and OvmfPkg too was rebased to the new core Pci Host Bridge Driver, in commit 4014885ffd: OvmfPkg: switch to MdeModulePkg/Bus/Pci/PciHostBridgeDxe This caused the optimization to go lost. Namely, the RootBridgeIoIoRead() and RootBridgeIoIoWrite() functions in the new core Pci Host Bridge Driver delegate IO port accesses to EFI_CPU_IO2_PROTOCOL. And, in OvmfPkg (and likely most other Ia32 / X64 edk2 platforms), this protocol is provided by "UefiCpuPkg/CpuIo2Dxe", which lacks the optimization. Therefore, this patch ports the C source code logic from commit 1fd376d9792 (see above) to "UefiCpuPkg/CpuIo2Dxe", plus it ports the NASM-converted assembly helper functions from OvmfPkg commits 6026bf460037 and ace1d0517b65: OvmfPkg PciHostBridgeDxe: Convert Ia32/IoFifo.asm to NASM OvmfPkg PciHostBridgeDxe: Convert X64/IoFifo.asm to NASM In order to support the MSFT and INTEL toolchains as well, the *.asm files are ported from OvmfPkg as well, immediately from before the above conversion (that is, at 6026bf460037^). * Notes about the port: - The write and read branches from commit 1fd376d9792 are split to the separate functions CpuIoServiceWrite() and CpuIoServiceRead(). - The EfiPciWidthUintXX constants are replaced with EfiCpuIoWidthUintXX. - The cast expression "(UINTN) Address" is replaced with "(UINTN)Address" (i.e., no space), because that's how the receiving functions spell it as well. - The labels in the switch statements are unindented by one level, to match the edk2 coding style (and the rest of UefiCpuPkg) better. * The first signoff belongs to Jordan, because he authored all of 1fd376d9792, 6026bf460037 and ace1d0517b65. Contributed-under: TianoCore Contribution Agreement 1.0 Signed-off-by: Jordan Justen <jordan.l.justen@intel.com> Contributed-under: TianoCore Contribution Agreement 1.0 Signed-off-by: Laszlo Ersek <lersek@redhat.com> Ref: https://www.redhat.com/archives/vfio-users/2016-April/msg00029.html Reported-by: Mark <kram321@gmail.com> Ref: http://thread.gmane.org/gmane.comp.bios.edk2.devel/10424/focus=10432 Reported-by: Jordan Justen <jordan.l.justen@intel.com> Cc: Jordan Justen <jordan.l.justen@intel.com> Cc: Ruiyu Ni <ruiyu.ni@intel.com> Cc: Jeff Fan <jeff.fan@intel.com> Cc: Mark <kram321@gmail.com> Tested-by: Mark <kram321@gmail.com> Reviewed-by: Jeff Fan <jeff.fan@intel.com>
2016-04-07 22:28:38 +02:00
;------------------------------------------------------------------------------
;
; Copyright (c) 2006 - 2012, Intel Corporation. All rights reserved.<BR>
;
; This program and the accompanying materials are licensed and made available
; under the terms and conditions of the BSD License which accompanies this
; distribution. The full text of the license may be found at
; http://opensource.org/licenses/bsd-license.php.
;
; THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
; WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
;
;------------------------------------------------------------------------------
.code
;------------------------------------------------------------------------------
; VOID
; EFIAPI
; IoReadFifo8 (
; IN UINTN Port, // rcx
; IN UINTN Size, // rdx
; IN VOID *Buffer // r8
; );
;------------------------------------------------------------------------------
IoReadFifo8 PROC
cld
xchg rcx, rdx
xchg rdi, r8 ; rdi: buffer address; r8: save rdi
rep insb
mov rdi, r8 ; restore rdi
ret
IoReadFifo8 ENDP
;------------------------------------------------------------------------------
; VOID
; EFIAPI
; IoReadFifo16 (
; IN UINTN Port, // rcx
; IN UINTN Size, // rdx
; IN VOID *Buffer // r8
; );
;------------------------------------------------------------------------------
IoReadFifo16 PROC
cld
xchg rcx, rdx
xchg rdi, r8 ; rdi: buffer address; r8: save rdi
rep insw
mov rdi, r8 ; restore rdi
ret
IoReadFifo16 ENDP
;------------------------------------------------------------------------------
; VOID
; EFIAPI
; IoReadFifo32 (
; IN UINTN Port, // rcx
; IN UINTN Size, // rdx
; IN VOID *Buffer // r8
; );
;------------------------------------------------------------------------------
IoReadFifo32 PROC
cld
xchg rcx, rdx
xchg rdi, r8 ; rdi: buffer address; r8: save rdi
rep insd
mov rdi, r8 ; restore rdi
ret
IoReadFifo32 ENDP
;------------------------------------------------------------------------------
; VOID
; EFIAPI
; IoWriteFifo8 (
; IN UINTN Port, // rcx
; IN UINTN Size, // rdx
; IN VOID *Buffer // r8
; );
;------------------------------------------------------------------------------
IoWriteFifo8 PROC
cld
xchg rcx, rdx
xchg rsi, r8 ; rsi: buffer address; r8: save rsi
rep outsb
mov rsi, r8 ; restore rsi
ret
IoWriteFifo8 ENDP
;------------------------------------------------------------------------------
; VOID
; EFIAPI
; IoWriteFifo16 (
; IN UINTN Port, // rcx
; IN UINTN Size, // rdx
; IN VOID *Buffer // r8
; );
;------------------------------------------------------------------------------
IoWriteFifo16 PROC
cld
xchg rcx, rdx
xchg rsi, r8 ; rsi: buffer address; r8: save rsi
rep outsw
mov rsi, r8 ; restore rsi
ret
IoWriteFifo16 ENDP
;------------------------------------------------------------------------------
; VOID
; EFIAPI
; IoWriteFifo32 (
; IN UINTN Port, // rcx
; IN UINTN Size, // rdx
; IN VOID *Buffer // r8
; );
;------------------------------------------------------------------------------
IoWriteFifo32 PROC
cld
xchg rcx, rdx
xchg rsi, r8 ; rsi: buffer address; r8: save rsi
rep outsd
mov rsi, r8 ; restore rsi
ret
IoWriteFifo32 ENDP
END