From 2c8dcbc65ab6d536731fe84081a7bdec55ebd495 Mon Sep 17 00:00:00 2001 From: Laszlo Ersek Date: Wed, 30 Nov 2016 13:13:40 +0100 Subject: OvmfPkg/QemuFwCfgLib: support QEMU's DMA-like fw_cfg access method The benefits of the DMA-like access method are (a) speed, (b) write support in QEMU 2.9+. (IOPort-based write support was discontinued in QEMU 2.4, and the DMA-based one is being added to QEMU 2.9. Write support needs no separate feature detection because writeability is governed on the level of individual fw_cfg files -- if a file meant to be written by the firmware exists in the directory, then it is writeable with the DMA method.) We don't enable this feature for the SEC library instance, because: - the SEC instance remains without clients (I've checked that it builds though), - in SEC, any possible fw_cfg use is expected to be small and read-only. Cc: Jordan Justen Contributed-under: TianoCore Contribution Agreement 1.0 Signed-off-by: Laszlo Ersek Reviewed-by: Jordan Justen --- OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgLib.c | 72 ++++++++++++++++++++++ .../Library/QemuFwCfgLib/QemuFwCfgLibInternal.h | 13 ++++ OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgPeiDxe.c | 25 +++++++- OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgSec.c | 15 +++++ 4 files changed, 124 insertions(+), 1 deletion(-) (limited to 'OvmfPkg') diff --git a/OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgLib.c b/OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgLib.c index 804d5b0e42..0bbf121de4 100644 --- a/OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgLib.c +++ b/OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgLib.c @@ -98,6 +98,70 @@ QemuFwCfgSelectItem ( } +/** + Transfer an array of bytes using the DMA interface. + + @param[in] Size Size in bytes to transfer. + @param[in,out] Buffer Buffer to read data into or write data from. May be + NULL if Size is zero. + @param[in] Write TRUE if writing to fw_cfg from Buffer, FALSE if + reading from fw_cfg into Buffer. +**/ +VOID +InternalQemuFwCfgDmaBytes ( + IN UINT32 Size, + IN OUT VOID *Buffer OPTIONAL, + IN BOOLEAN Write + ) +{ + volatile FW_CFG_DMA_ACCESS Access; + UINT32 AccessHigh, AccessLow; + UINT32 Status; + + if (Size == 0) { + return; + } + + Access.Control = SwapBytes32 ( + Write ? FW_CFG_DMA_CTL_WRITE : FW_CFG_DMA_CTL_READ + ); + Access.Length = SwapBytes32 (Size); + Access.Address = SwapBytes64 ((UINTN)Buffer); + + // + // Delimit the transfer from (a) modifications to Access, (b) in case of a + // write, from writes to Buffer by the caller. + // + MemoryFence (); + + // + // Start the transfer. + // + AccessHigh = (UINT32)RShiftU64 ((UINTN)&Access, 32); + AccessLow = (UINT32)(UINTN)&Access; + IoWrite32 (0x514, SwapBytes32 (AccessHigh)); + IoWrite32 (0x518, SwapBytes32 (AccessLow)); + + // + // Don't look at Access.Control before starting the transfer. + // + MemoryFence (); + + // + // Wait for the transfer to complete. + // + do { + Status = SwapBytes32 (Access.Control); + ASSERT ((Status & FW_CFG_DMA_CTL_ERROR) == 0); + } while (Status != 0); + + // + // After a read, the caller will want to use Buffer. + // + MemoryFence (); +} + + /** Reads firmware configuration bytes into a buffer @@ -112,6 +176,10 @@ InternalQemuFwCfgReadBytes ( IN VOID *Buffer OPTIONAL ) { + if (InternalQemuFwCfgDmaIsAvailable () && Size <= MAX_UINT32) { + InternalQemuFwCfgDmaBytes ((UINT32)Size, Buffer, FALSE); + return; + } IoReadFifo8 (0x511, Size, Buffer); } @@ -160,6 +228,10 @@ QemuFwCfgWriteBytes ( ) { if (InternalQemuFwCfgIsAvailable ()) { + if (InternalQemuFwCfgDmaIsAvailable () && Size <= MAX_UINT32) { + InternalQemuFwCfgDmaBytes ((UINT32)Size, Buffer, TRUE); + return; + } IoWriteFifo8 (0x511, Size, Buffer); } } diff --git a/OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgLibInternal.h b/OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgLibInternal.h index 5b162bf987..6e87c62510 100644 --- a/OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgLibInternal.h +++ b/OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgLibInternal.h @@ -30,4 +30,17 @@ InternalQemuFwCfgIsAvailable ( VOID ); + +/** + Returns a boolean indicating whether QEMU provides the DMA-like access method + for fw_cfg. + + @retval TRUE The DMA-like access method is available. + @retval FALSE The DMA-like access method is unavailable. +**/ +BOOLEAN +InternalQemuFwCfgDmaIsAvailable ( + VOID + ); + #endif diff --git a/OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgPeiDxe.c b/OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgPeiDxe.c index 88d88c0edf..ac05f4c347 100644 --- a/OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgPeiDxe.c +++ b/OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgPeiDxe.c @@ -20,6 +20,7 @@ #include "QemuFwCfgLibInternal.h" STATIC BOOLEAN mQemuFwCfgSupported = FALSE; +STATIC BOOLEAN mQemuFwCfgDmaSupported; /** @@ -53,8 +54,10 @@ QemuFwCfgInitialize ( // // Enable the access routines while probing to see if it is supported. + // For probing we always use the IO Port (IoReadFifo8()) access method. // mQemuFwCfgSupported = TRUE; + mQemuFwCfgDmaSupported = FALSE; QemuFwCfgSelectItem (QemuFwCfgItemSignature); Signature = QemuFwCfgRead32 (); @@ -70,7 +73,12 @@ QemuFwCfgInitialize ( return RETURN_SUCCESS; } - DEBUG ((EFI_D_INFO, "QemuFwCfg interface is supported.\n")); + if ((Revision & FW_CFG_F_DMA) == 0) { + DEBUG ((DEBUG_INFO, "QemuFwCfg interface (IO Port) is supported.\n")); + } else { + mQemuFwCfgDmaSupported = TRUE; + DEBUG ((DEBUG_INFO, "QemuFwCfg interface (DMA) is supported.\n")); + } return RETURN_SUCCESS; } @@ -91,3 +99,18 @@ InternalQemuFwCfgIsAvailable ( { return mQemuFwCfgSupported; } + +/** + Returns a boolean indicating whether QEMU provides the DMA-like access method + for fw_cfg. + + @retval TRUE The DMA-like access method is available. + @retval FALSE The DMA-like access method is unavailable. +**/ +BOOLEAN +InternalQemuFwCfgDmaIsAvailable ( + VOID + ) +{ + return mQemuFwCfgDmaSupported; +} diff --git a/OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgSec.c b/OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgSec.c index 56c59ca3f0..465ccbe90d 100644 --- a/OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgSec.c +++ b/OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgSec.c @@ -79,3 +79,18 @@ InternalQemuFwCfgIsAvailable ( // return TRUE; } + +/** + Returns a boolean indicating whether QEMU provides the DMA-like access method + for fw_cfg. + + @retval TRUE The DMA-like access method is available. + @retval FALSE The DMA-like access method is unavailable. +**/ +BOOLEAN +InternalQemuFwCfgDmaIsAvailable ( + VOID + ) +{ + return FALSE; +} -- cgit v1.2.3