[edk2-devel] [PATCH v3 13/17] OvmfPkg/PvScsiDxe: Setup requests and completions rings
Laszlo Ersek
lersek at redhat.com
Mon Mar 30 15:54:32 UTC 2020
On 03/28/20 21:00, Liran Alon wrote:
> These rings are shared memory buffers between host and device in which
> a cyclic buffer is managed to send request descriptors from host to
> device and receive completion descriptors from device to host.
>
> Note that because device may be constrained by IOMMU or guest may be run
> under AMD SEV, we make sure to map these rings to device by using
> PciIo->Map().
>
> Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=2567
> Signed-off-by: Liran Alon <liran.alon at oracle.com>
> ---
> OvmfPkg/PvScsiDxe/PvScsi.c | 219 ++++++++++++++++++++++++++++++++
> OvmfPkg/PvScsiDxe/PvScsi.h | 17 +++
> OvmfPkg/PvScsiDxe/PvScsiDxe.inf | 1 +
> 3 files changed, 237 insertions(+)
>
> diff --git a/OvmfPkg/PvScsiDxe/PvScsi.c b/OvmfPkg/PvScsiDxe/PvScsi.c
> index cf75884350ee..c7d367e83a2d 100644
> --- a/OvmfPkg/PvScsiDxe/PvScsi.c
> +++ b/OvmfPkg/PvScsiDxe/PvScsi.c
> @@ -11,11 +11,13 @@
>
> #include <IndustryStandard/Pci.h>
> #include <IndustryStandard/PvScsi.h>
> +#include <Library/BaseLib.h>
> #include <Library/BaseMemoryLib.h>
> #include <Library/MemoryAllocationLib.h>
> #include <Library/UefiBootServicesTableLib.h>
> #include <Library/UefiLib.h>
> #include <Protocol/PciIo.h>
> +#include <Protocol/PciRootBridgeIo.h>
> #include <Uefi/UefiSpec.h>
>
> #include "PvScsi.h"
> @@ -436,6 +438,207 @@ PvScsiRestorePciAttributes (
> );
> }
>
> +STATIC
> +EFI_STATUS
> +PvScsiAllocateSharedPages (
> + IN PVSCSI_DEV *Dev,
> + IN UINTN Pages,
> + OUT VOID **HostAddress,
> + OUT PVSCSI_DMA_DESC *DmaDesc
> + )
> +{
> + EFI_STATUS Status;
> + UINTN NumberOfBytes;
> +
> + Status = Dev->PciIo->AllocateBuffer (
> + Dev->PciIo,
> + AllocateAnyPages,
> + EfiBootServicesData,
> + Pages,
> + HostAddress,
> + EFI_PCI_ATTRIBUTE_MEMORY_CACHED
> + );
> + if (EFI_ERROR (Status)) {
> + return Status;
> + }
> +
> + NumberOfBytes = EFI_PAGES_TO_SIZE (Pages);
> + Status = Dev->PciIo->Map (
> + Dev->PciIo,
> + EfiPciIoOperationBusMasterCommonBuffer,
> + *HostAddress,
> + &NumberOfBytes,
> + &DmaDesc->DeviceAddress,
> + &DmaDesc->Mapping
> + );
> + if (EFI_ERROR (Status)) {
> + goto FreeBuffer;
> + }
> +
> + if (NumberOfBytes != EFI_PAGES_TO_SIZE (Pages)) {
> + Status = EFI_OUT_OF_RESOURCES;
> + goto Unmap;
> + }
> +
> + return EFI_SUCCESS;
> +
> +Unmap:
> + Dev->PciIo->Unmap (Dev->PciIo, DmaDesc->Mapping);
> +
> +FreeBuffer:
> + Dev->PciIo->FreeBuffer (Dev->PciIo, Pages, *HostAddress);
> +
> + return Status;
> +}
> +
> +STATIC
> +VOID
> +PvScsiFreeSharedPages (
> + IN PVSCSI_DEV *Dev,
> + IN UINTN Pages,
> + IN VOID *HostAddress,
> + IN PVSCSI_DMA_DESC *DmaDesc
> + )
> +{
> + Dev->PciIo->Unmap (Dev->PciIo, DmaDesc->Mapping);
> + Dev->PciIo->FreeBuffer (Dev->PciIo, Pages, HostAddress);
> +}
> +
> +STATIC
> +EFI_STATUS
> +PvScsiInitRings (
> + IN OUT PVSCSI_DEV *Dev
> + )
> +{
> + EFI_STATUS Status;
> + union {
> + PVSCSI_CMD_DESC_SETUP_RINGS Cmd;
> + UINT32 Uint32;
> + } AlignedCmd;
> + PVSCSI_CMD_DESC_SETUP_RINGS *Cmd;
> +
> + Cmd = &AlignedCmd.Cmd;
> +
> + Status = PvScsiAllocateSharedPages (
> + Dev,
> + 1,
> + (VOID **)&Dev->RingDesc.RingState,
> + &Dev->RingDesc.RingStateDmaDesc
> + );
> + if (EFI_ERROR (Status)) {
> + return Status;
> + }
> + ZeroMem (Dev->RingDesc.RingState, EFI_PAGE_SIZE);
> +
> + Status = PvScsiAllocateSharedPages (
> + Dev,
> + 1,
> + (VOID **)&Dev->RingDesc.RingReqs,
> + &Dev->RingDesc.RingReqsDmaDesc
> + );
> + if (EFI_ERROR (Status)) {
> + goto FreeRingState;
> + }
> + ZeroMem (Dev->RingDesc.RingReqs, EFI_PAGE_SIZE);
> +
> + Status = PvScsiAllocateSharedPages (
> + Dev,
> + 1,
> + (VOID **)&Dev->RingDesc.RingCmps,
> + &Dev->RingDesc.RingCmpsDmaDesc
> + );
> + if (EFI_ERROR (Status)) {
> + goto FreeRingReqs;
> + }
> + ZeroMem (Dev->RingDesc.RingCmps, EFI_PAGE_SIZE);
> +
> + ZeroMem (Cmd, sizeof (*Cmd));
> + Cmd->ReqRingNumPages = 1;
> + Cmd->CmpRingNumPages = 1;
> + Cmd->RingsStatePPN = RShiftU64 (
> + Dev->RingDesc.RingStateDmaDesc.DeviceAddress,
> + EFI_PAGE_SHIFT
> + );
> + Cmd->ReqRingPPNs[0] = RShiftU64 (
> + Dev->RingDesc.RingReqsDmaDesc.DeviceAddress,
> + EFI_PAGE_SHIFT
> + );
> + Cmd->CmpRingPPNs[0] = RShiftU64 (
> + Dev->RingDesc.RingCmpsDmaDesc.DeviceAddress,
> + EFI_PAGE_SHIFT
> + );
> +
> + STATIC_ASSERT (
> + sizeof (*Cmd) % sizeof (UINT32) == 0,
> + "Cmd must be multiple of 32-bit words"
> + );
> + Status = PvScsiWriteCmdDesc (
> + Dev,
> + PvScsiCmdSetupRings,
> + (UINT32 *)Cmd,
> + sizeof (*Cmd) / sizeof (UINT32)
> + );
> + if (EFI_ERROR (Status)) {
> + goto FreeRingCmps;
> + }
> +
> + return EFI_SUCCESS;
> +
> +FreeRingCmps:
> + PvScsiFreeSharedPages (
> + Dev,
> + 1,
> + Dev->RingDesc.RingCmps,
> + &Dev->RingDesc.RingCmpsDmaDesc
> + );
> +
> +FreeRingReqs:
> + PvScsiFreeSharedPages (
> + Dev,
> + 1,
> + Dev->RingDesc.RingReqs,
> + &Dev->RingDesc.RingReqsDmaDesc
> + );
> +
> +FreeRingState:
> + PvScsiFreeSharedPages (
> + Dev,
> + 1,
> + Dev->RingDesc.RingState,
> + &Dev->RingDesc.RingStateDmaDesc
> + );
> +
> + return Status;
> +}
> +
> +STATIC
> +VOID
> +PvScsiFreeRings (
> + IN OUT PVSCSI_DEV *Dev
> + )
> +{
> + PvScsiFreeSharedPages (
> + Dev,
> + 1,
> + Dev->RingDesc.RingCmps,
> + &Dev->RingDesc.RingCmpsDmaDesc
> + );
> +
> + PvScsiFreeSharedPages (
> + Dev,
> + 1,
> + Dev->RingDesc.RingReqs,
> + &Dev->RingDesc.RingReqsDmaDesc
> + );
> +
> + PvScsiFreeSharedPages (
> + Dev,
> + 1,
> + Dev->RingDesc.RingState,
> + &Dev->RingDesc.RingStateDmaDesc
> + );
> +}
> +
> STATIC
> EFI_STATUS
> PvScsiInit (
> @@ -466,6 +669,14 @@ PvScsiInit (
> goto RestorePciAttributes;
> }
>
> + //
> + // Init PVSCSI rings
> + //
> + Status = PvScsiInitRings (Dev);
> + if (EFI_ERROR (Status)) {
> + goto RestorePciAttributes;
> + }
> +
> //
> // Populate the exported interface's attributes
> //
> @@ -509,6 +720,14 @@ PvScsiUninit (
> IN OUT PVSCSI_DEV *Dev
> )
> {
> + //
> + // Reset device to stop device usage of the rings.
> + // This is required to safely free the rings.
> + //
> + PvScsiResetAdapter (Dev);
If I understand correctly (at the end of the series):
in order to save one of the (ultimately) two reset calls in
PvScsiUninit(), namely
- one for releasing the DMA buf
- and the other (internal to PvScsiFreeRings()) for releasing the rings,
you unnested the latter reset call from PvScsiFreeRings(), and added it
manually to the error path of PvScsiInit().
To me, that's more brittle and more difficult to reason about than what
I proposed, because now PvScsiFreeRings() does not completely undo
PvScsiInitRings(). I specifically requested that we please not try to
save on the two (seemingly) redundant reset calls in PvScsiUninit() --
see the paragraph containing "bad idea" here:
http://mid.mail-archive.com/45e5950c-ec82-c24b-4c38-2912402747b2@redhat.com
https://edk2.groups.io/g/devel/message/56425
(Note: we could be tempted to somehow "centralize" all of these
Reset operations into a single spot. Bad idea. We are revoking the
device's access rights to different resources, so the revocation
operations will show up in different spots. It's a mere circumstance
that the revocations all happen to be Reset operations.)
I might be paranoid of course -- I just feel that maybe-superfluous
reset operations on error paths are much better than silently
corrupted guest memory and/or disk contents.
You reacted to that message of mine, but not this paragraph specifically
(it was snipped from your followup) -- so I thought you were OK with it.
I'm a bit disappointed that you disagreed with my request *silently*.
To summarize: technically, your solution is correct; from a code hygiene
and resource ownership question, I'm convinced it is wrong.
But, I'll live with it.
Reviewed-by: Laszlo Ersek <lersek at redhat.com>
(Also, you didn't set up the "diff.orderFile" knob the way I requested
in point (8):
http://mid.mail-archive.com/0739202a-9b8a-759d-5809-2f2df69e9352@redhat.com
https://edk2.groups.io/g/devel/message/56420
and so the header file changes are again at the end of the patch...
Another thing I'll have to live with, I guess.)
Laszlo
> +
> + PvScsiFreeRings (Dev);
> +
> PvScsiRestorePciAttributes (Dev);
> }
>
> diff --git a/OvmfPkg/PvScsiDxe/PvScsi.h b/OvmfPkg/PvScsiDxe/PvScsi.h
> index 5f611dbbc98c..6d23b6e1eccf 100644
> --- a/OvmfPkg/PvScsiDxe/PvScsi.h
> +++ b/OvmfPkg/PvScsiDxe/PvScsi.h
> @@ -15,12 +15,29 @@
> #include <Library/DebugLib.h>
> #include <Protocol/ScsiPassThruExt.h>
>
> +typedef struct {
> + EFI_PHYSICAL_ADDRESS DeviceAddress;
> + VOID *Mapping;
> +} PVSCSI_DMA_DESC;
> +
> +typedef struct {
> + PVSCSI_RINGS_STATE *RingState;
> + PVSCSI_DMA_DESC RingStateDmaDesc;
> +
> + PVSCSI_RING_REQ_DESC *RingReqs;
> + PVSCSI_DMA_DESC RingReqsDmaDesc;
> +
> + PVSCSI_RING_CMP_DESC *RingCmps;
> + PVSCSI_DMA_DESC RingCmpsDmaDesc;
> +} PVSCSI_RING_DESC;
> +
> #define PVSCSI_SIG SIGNATURE_32 ('P', 'S', 'C', 'S')
>
> typedef struct {
> UINT32 Signature;
> EFI_PCI_IO_PROTOCOL *PciIo;
> UINT64 OriginalPciAttributes;
> + PVSCSI_RING_DESC RingDesc;
> UINT8 MaxTarget;
> UINT8 MaxLun;
> EFI_EXT_SCSI_PASS_THRU_PROTOCOL PassThru;
> diff --git a/OvmfPkg/PvScsiDxe/PvScsiDxe.inf b/OvmfPkg/PvScsiDxe/PvScsiDxe.inf
> index fcffc90d46c8..6200533698fc 100644
> --- a/OvmfPkg/PvScsiDxe/PvScsiDxe.inf
> +++ b/OvmfPkg/PvScsiDxe/PvScsiDxe.inf
> @@ -26,6 +26,7 @@
> OvmfPkg/OvmfPkg.dec
>
> [LibraryClasses]
> + BaseLib
> BaseMemoryLib
> DebugLib
> MemoryAllocationLib
>
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