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Re: [Qemu-devel] [PATCH v1 1/3] sPAPR: Implement PCI error injection RTA


From: Alexander Graf
Subject: Re: [Qemu-devel] [PATCH v1 1/3] sPAPR: Implement PCI error injection RTAS calls
Date: Mon, 23 Jun 2014 18:18:37 +0200
User-agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.9; rv:24.0) Gecko/20100101 Thunderbird/24.6.0


On 23.06.14 04:22, Gavin Shan wrote:
The patch implements PCI error injection RTAS calls for sPAPR
platform, which are defined PAPR spec as follows. Those RTAS
calls are expected to be invoked in strict sequence of
"ibm,open-errinjct", "ibm,errinjct", "ibm,close-errinjct".

- "ibm,open-errinjct": Apply for token to do error injection
- "ibm,close-errinjct": Free the token assigned previously
- "ibm,errinjct": Do error injection

The patch defines constants used by error injection RTAS calls
and adds callback sPAPRPHBClass::format_errinjct_cmd, which is
going to be used like this way:

- Error injection RTAS calls are received in spapr_rtas.c. If that's
   "ibm,open-errinjct" or "ibm,close-errinjct", we handle it there
   with the help of static counter "sPAPREnvironment::errinjct_token_cnt".
   If the  RTAS call is "ibm,errinjct", sanity check is done there and
   just returns failure if the error type isn't PCI related. Otherwise,
   the input parameters are figured out and route the request to
   sPAPRPHBClass::format_errinjct_cmd.
- sPAPRPHBClass::format_errinjct_cmd translates the address (BUID, PE
   number) to IOMMU group ID and then return the formated string back to
   spapr_rtas.c where the string is writen to firmware sysfs file
   "/sys/firmware/opal/errinjct" to do error injection.

Signed-off-by: Gavin Shan <address@hidden>
---
  hw/ppc/spapr_rtas.c         | 198 ++++++++++++++++++++++++++++++++++++++++++++
  include/hw/pci-host/spapr.h |  11 +++
  include/hw/ppc/spapr.h      |  35 ++++++++
  3 files changed, 244 insertions(+)

diff --git a/hw/ppc/spapr_rtas.c b/hw/ppc/spapr_rtas.c
index a7233e4..94fb866 100644
--- a/hw/ppc/spapr_rtas.c
+++ b/hw/ppc/spapr_rtas.c
@@ -32,6 +32,7 @@
#include "hw/ppc/spapr.h"
  #include "hw/ppc/spapr_vio.h"
+#include "hw/pci-host/spapr.h"
#include <libfdt.h> @@ -268,6 +269,196 @@ static void rtas_ibm_set_system_parameter(PowerPCCPU *cpu,
      rtas_st(rets, 0, ret);
  }
+static sPAPRErrInjct *rtas_find_errinjct_token(sPAPREnvironment *spapr,
+                                               uint32_t token_num)
+{
+    sPAPRErrInjct *open_token;
+
+    QLIST_FOREACH(open_token, &spapr->errinjct_open_tokens, list) {
+        if (open_token->token == token_num) {
+            return open_token;
+        }
+    }
+
+    return NULL;
+}
+
+static void rtas_ibm_open_errinjct(PowerPCCPU *cpu,
+                                   sPAPREnvironment *spapr,
+                                   uint32_t token, uint32_t nargs,
+                                   target_ulong args, uint32_t nret,
+                                   target_ulong rets)
+{
+    sPAPRErrInjct *open_token;
+    int32_t ret = RTAS_OUT_HW_ERROR;
+
+    /* Sanity check on number of arguments */
+    if ((nargs != 0) || (nret != 2)) {
+        goto out;
+    }
+
+    /* Allocate token */
+    open_token = g_malloc(sizeof(*open_token));

With this hypercall the guest can OOM us by simply allocating useless tokens.

+    if (!open_token) {
+        goto out;
+    }
+    open_token->token = spapr->errinjct_open_token_cnt++;
+    QLIST_INSERT_HEAD(&spapr->errinjct_open_tokens, open_token, list);
+
+    /* Success */
+    rtas_st(rets, 0, open_token->token);
+    ret = RTAS_OUT_SUCCESS;
+out:
+    rtas_st(rets, 1, ret);
+}
+
+static char *rtas_do_errinjct_ioa(sPAPREnvironment *spapr,
+                                sPAPRErrInjctIOA *ioa)
+{
+    sPAPRPHBState *sphb;
+    sPAPRPHBClass *info;
+
+    /* Sanity check on argument */
+    if (!spapr || !ioa) {
+        return NULL;
+    }
+
+    /* Invalid option ? */
+    if (ioa->func > RTAS_ERRINJCT_IOA_DMA_WR_MEM_TARGET) {
+        return NULL;
+    }
+
+    /* Find PHB */
+    sphb = spapr_find_phb(spapr, ioa->buid);
+    if (!sphb) {
+        return NULL;
+    }
+
+    /* PHB doesn't support error injection ? */
+    info = SPAPR_PCI_HOST_BRIDGE_GET_CLASS(sphb);
+    if (!info->format_errinjct_cmd) {
+        return NULL;
+    }
+
+    return info->format_errinjct_cmd(sphb, ioa);
+}
+
+static void rtas_ibm_errinjct(PowerPCCPU *cpu,
+                              sPAPREnvironment *spapr,
+                              uint32_t token, uint32_t nargs,
+                              target_ulong args, uint32_t nret,
+                              target_ulong rets)
+{
+    sPAPRErrInjctIOA ioa;
+    sPAPRErrInjct *open_token;
+    uint32_t token_num, ei_token;
+    target_ulong param_buf;
+    char *pbuf;
+    int fd;
+    int32_t ret = RTAS_OUT_PARAM_ERROR;
+
+    /* Sanity check on number of arguments */
+    if ((nargs != 3) || (nret != 1)) {
+        goto out;
+    }
+
+    /* Check if we have opened token */
+    token_num = rtas_ld(args, 1);
+    open_token = rtas_find_errinjct_token(spapr, token_num);
+    if (!open_token) {
+        goto out;
+    }
+
+    /* Argument buffer should be aligned with 1KB */
+    param_buf = rtas_ld(args, 2);
+    if (param_buf & 0x3ff) {
+        goto out;
+    }
+
+    /* We only support IOA error for now */
+    ei_token = rtas_ld(args, 0);
+    switch (ei_token) {
+    case RTAS_ERRINJCT_TYPE_IOA_BUS_ERROR:
+        ioa.ei_token = RTAS_ERRINJCT_TYPE_IOA_BUS_ERROR;
+        ioa.addr = rtas_ld(param_buf, 0);
+        ioa.mask = rtas_ld(param_buf, 1);
+        ioa.cfg_addr = rtas_ld(param_buf, 2);
+        ioa.buid = ((uint64_t)rtas_ld(param_buf, 3) << 32) | 
rtas_ld(param_buf, 4);
+        ioa.func = rtas_ld(param_buf, 5);
+
+        break;
+    case RTAS_ERRINJCT_TYPE_IOA_BUS_ERROR64:
+        ioa.ei_token = RTAS_ERRINJCT_TYPE_IOA_BUS_ERROR64;
+        ioa.addr = ((uint64_t)rtas_ld(param_buf, 0) << 32) | 
rtas_ld(param_buf, 1);
+        ioa.mask = ((uint64_t)rtas_ld(param_buf, 2) << 32) | 
rtas_ld(param_buf, 3);
+        ioa.cfg_addr = rtas_ld(param_buf, 4);
+        ioa.buid = ((uint64_t)rtas_ld(param_buf, 5) << 32) | 
rtas_ld(param_buf, 6);
+        ioa.func = rtas_ld(param_buf, 7);
+
+        break;
+    default:
+        goto out;
+    }
+
+    /* We have nothing written to sysfs */
+    pbuf = rtas_do_errinjct_ioa(spapr, &ioa);
+    if (!pbuf) {
+        goto out;
+    }
+
+    /* Open firmware sysfs file */
+    fd = qemu_open("/sys/firmware/opal/errinjct", O_WRONLY);

Device emulation code shouldn't even remotely have an idea what host it's running on. Also semantically there are a few issues with this approach

1) QEMU is usually running with user privileges, so it doesn't have access to the file above 2) QEMU's channel to hardware devices is via normal kernel API. For physical devices that's VFIO. No side channels please. 3) Ownership of the question whether a PE is in error mode is responsibility of the PHB. In the emulated case, the PHB would have to set itself into a mode where it behaves as if it's blocked.


Alex




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