qemu-e2k/include/hw/scsi/esp.h
Guenter Roeck ea84a44250 scsi: esp: Defer command completion until previous interrupts have been handled
The guest OS reads RSTAT, RSEQ, and RINTR, and expects those registers
to reflect a consistent state. However, it is possible that the registers
can change after RSTAT was read, but before RINTR is read, when
esp_command_complete() is called.

Guest OS		qemu
--------		----
[handle interrupt]
Read RSTAT
			esp_command_complete()
			 RSTAT = STAT_ST
			 esp_dma_done()
			  RSTAT |= STAT_TC
			  RSEQ = 0
			  RINTR = INTR_BS

Read RSEQ
Read RINTR		RINTR = 0
			RSTAT &= ~STAT_TC
			RSEQ = SEQ_CD

The guest OS would then try to handle INTR_BS combined with an old
value of RSTAT. This sometimes resulted in lost events, spurious
interrupts, guest OS confusion, and stalled SCSI operations.
A typical guest error log (observed with various versions of Linux)
looks as follows.

scsi host1: Spurious irq, sreg=13.
...
scsi host1: Aborting command [84531f10:2a]
scsi host1: Current command [f882eea8:35]
scsi host1: Queued command [84531f10:2a]
scsi host1:  Active command [f882eea8:35]
scsi host1: Dumping command log
scsi host1: ent[15] CMD val[44] sreg[90] seqreg[00] sreg2[00] ireg[20] ss[00] event[0c]
scsi host1: ent[16] CMD val[01] sreg[90] seqreg[00] sreg2[00] ireg[20] ss[02] event[0c]
scsi host1: ent[17] CMD val[43] sreg[90] seqreg[00] sreg2[00] ireg[20] ss[02] event[0c]
scsi host1: ent[18] EVENT val[0d] sreg[92] seqreg[04] sreg2[00] ireg[18] ss[00] event[0c]
...

Defer handling command completion until previous interrupts have been
handled to fix the problem.

Signed-off-by: Guenter Roeck <linux@roeck-us.net>
2019-01-11 13:57:24 +01:00

146 lines
3.2 KiB
C

#ifndef QEMU_HW_ESP_H
#define QEMU_HW_ESP_H
#include "hw/scsi/scsi.h"
#include "hw/sysbus.h"
/* esp.c */
#define ESP_MAX_DEVS 7
typedef void (*ESPDMAMemoryReadWriteFunc)(void *opaque, uint8_t *buf, int len);
#define ESP_REGS 16
#define TI_BUFSZ 16
#define ESP_CMDBUF_SZ 32
typedef struct ESPState ESPState;
struct ESPState {
uint8_t rregs[ESP_REGS];
uint8_t wregs[ESP_REGS];
qemu_irq irq;
uint8_t chip_id;
bool tchi_written;
int32_t ti_size;
uint32_t ti_rptr, ti_wptr;
uint32_t status;
uint32_t deferred_status;
bool deferred_complete;
uint32_t dma;
uint8_t ti_buf[TI_BUFSZ];
SCSIBus bus;
SCSIDevice *current_dev;
SCSIRequest *current_req;
uint8_t cmdbuf[ESP_CMDBUF_SZ];
uint32_t cmdlen;
uint32_t do_cmd;
/* The amount of data left in the current DMA transfer. */
uint32_t dma_left;
/* The size of the current DMA transfer. Zero if no transfer is in
progress. */
uint32_t dma_counter;
int dma_enabled;
uint32_t async_len;
uint8_t *async_buf;
ESPDMAMemoryReadWriteFunc dma_memory_read;
ESPDMAMemoryReadWriteFunc dma_memory_write;
void *dma_opaque;
void (*dma_cb)(ESPState *s);
};
#define TYPE_ESP "esp"
#define ESP_STATE(obj) OBJECT_CHECK(SysBusESPState, (obj), TYPE_ESP)
typedef struct {
/*< private >*/
SysBusDevice parent_obj;
/*< public >*/
MemoryRegion iomem;
uint32_t it_shift;
ESPState esp;
} SysBusESPState;
#define ESP_TCLO 0x0
#define ESP_TCMID 0x1
#define ESP_FIFO 0x2
#define ESP_CMD 0x3
#define ESP_RSTAT 0x4
#define ESP_WBUSID 0x4
#define ESP_RINTR 0x5
#define ESP_WSEL 0x5
#define ESP_RSEQ 0x6
#define ESP_WSYNTP 0x6
#define ESP_RFLAGS 0x7
#define ESP_WSYNO 0x7
#define ESP_CFG1 0x8
#define ESP_RRES1 0x9
#define ESP_WCCF 0x9
#define ESP_RRES2 0xa
#define ESP_WTEST 0xa
#define ESP_CFG2 0xb
#define ESP_CFG3 0xc
#define ESP_RES3 0xd
#define ESP_TCHI 0xe
#define ESP_RES4 0xf
#define CMD_DMA 0x80
#define CMD_CMD 0x7f
#define CMD_NOP 0x00
#define CMD_FLUSH 0x01
#define CMD_RESET 0x02
#define CMD_BUSRESET 0x03
#define CMD_TI 0x10
#define CMD_ICCS 0x11
#define CMD_MSGACC 0x12
#define CMD_PAD 0x18
#define CMD_SATN 0x1a
#define CMD_RSTATN 0x1b
#define CMD_SEL 0x41
#define CMD_SELATN 0x42
#define CMD_SELATNS 0x43
#define CMD_ENSEL 0x44
#define CMD_DISSEL 0x45
#define STAT_DO 0x00
#define STAT_DI 0x01
#define STAT_CD 0x02
#define STAT_ST 0x03
#define STAT_MO 0x06
#define STAT_MI 0x07
#define STAT_PIO_MASK 0x06
#define STAT_TC 0x10
#define STAT_PE 0x20
#define STAT_GE 0x40
#define STAT_INT 0x80
#define BUSID_DID 0x07
#define INTR_FC 0x08
#define INTR_BS 0x10
#define INTR_DC 0x20
#define INTR_RST 0x80
#define SEQ_0 0x0
#define SEQ_CD 0x4
#define CFG1_RESREPT 0x40
#define TCHI_FAS100A 0x4
#define TCHI_AM53C974 0x12
void esp_dma_enable(ESPState *s, int irq, int level);
void esp_request_cancelled(SCSIRequest *req);
void esp_command_complete(SCSIRequest *req, uint32_t status, size_t resid);
void esp_transfer_data(SCSIRequest *req, uint32_t len);
void esp_hard_reset(ESPState *s);
uint64_t esp_reg_read(ESPState *s, uint32_t saddr);
void esp_reg_write(ESPState *s, uint32_t saddr, uint64_t val);
extern const VMStateDescription vmstate_esp;
#endif