[Qemu-devel] [PATCH v4 03/14] spapr/xive: add hcall support when under KVM

[Cédric Le Goater]

XIVE hcalls are all redirected to QEMU as none are on a fast path.
When necessary, QEMU invokes KVM through specific ioctls to perform
host operations. QEMU should have done the necessary checks before
calling KVM and, in case of failure, H_HARDWARE is simply returned.

H_INT_ESB is a special case that could have been handled under KVM
but the impact on performance was low when under QEMU. Here are some
figures :

    kernel irqchip      OFF          ON
    H_INT_ESB                    KVM   QEMU

    rtl8139 (LSI )      1.19     1.24  1.23  Gbits/sec
    virtio             31.80    42.30   --   Gbits/sec

Signed-off-by: Cédric Le Goater <address@hidden>
Reviewed-by: David Gibson <address@hidden>
---

 Changes since v3:

 - added usage of xive_end_qaddr() helper

 include/hw/ppc/spapr_xive.h |  15 +++
 hw/intc/spapr_xive.c        |  90 ++++++++++++++--
 hw/intc/spapr_xive_kvm.c    | 197 ++++++++++++++++++++++++++++++++++++
 3 files changed, 294 insertions(+), 8 deletions(-)

diff --git a/include/hw/ppc/spapr_xive.h b/include/hw/ppc/spapr_xive.h
index 0edcc762dedd..03685910e76b 100644
--- a/include/hw/ppc/spapr_xive.h
+++ b/include/hw/ppc/spapr_xive.h
@@ -55,9 +55,24 @@ void spapr_xive_set_tctx_os_cam(XiveTCTX *tctx);
 void spapr_xive_mmio_set_enabled(SpaprXive *xive, bool enable);
 void spapr_xive_map_mmio(SpaprXive *xive);
 
+int spapr_xive_end_to_target(uint8_t end_blk, uint32_t end_idx,
+                             uint32_t *out_server, uint8_t *out_prio);
+
 /*
  * KVM XIVE device helpers
  */
 void kvmppc_xive_connect(SpaprXive *xive, Error **errp);
+void kvmppc_xive_reset(SpaprXive *xive, Error **errp);
+void kvmppc_xive_set_source_config(SpaprXive *xive, uint32_t lisn, XiveEAS 
*eas,
+                                   Error **errp);
+void kvmppc_xive_sync_source(SpaprXive *xive, uint32_t lisn, Error **errp);
+uint64_t kvmppc_xive_esb_rw(XiveSource *xsrc, int srcno, uint32_t offset,
+                            uint64_t data, bool write);
+void kvmppc_xive_set_queue_config(SpaprXive *xive, uint8_t end_blk,
+                                 uint32_t end_idx, XiveEND *end,
+                                 Error **errp);
+void kvmppc_xive_get_queue_config(SpaprXive *xive, uint8_t end_blk,
+                                 uint32_t end_idx, XiveEND *end,
+                                 Error **errp);
 
 #endif /* PPC_SPAPR_XIVE_H */
diff --git a/hw/intc/spapr_xive.c b/hw/intc/spapr_xive.c
index 1390fc109c80..6beda26ee440 100644
--- a/hw/intc/spapr_xive.c
+++ b/hw/intc/spapr_xive.c
@@ -86,6 +86,22 @@ static int spapr_xive_target_to_nvt(uint32_t target,
  * sPAPR END indexing uses a simple mapping of the CPU vcpu_id, 8
  * priorities per CPU
  */
+int spapr_xive_end_to_target(uint8_t end_blk, uint32_t end_idx,
+                             uint32_t *out_server, uint8_t *out_prio)
+{
+
+    assert(end_blk == SPAPR_XIVE_BLOCK_ID);
+
+    if (out_server) {
+        *out_server = end_idx >> 3;
+    }
+
+    if (out_prio) {
+        *out_prio = end_idx & 0x7;
+    }
+    return 0;
+}
+
 static void spapr_xive_cpu_to_end(PowerPCCPU *cpu, uint8_t prio,
                                   uint8_t *out_end_blk, uint32_t *out_end_idx)
 {
@@ -792,6 +808,16 @@ static target_ulong h_int_set_source_config(PowerPCCPU 
*cpu,
         new_eas.w = xive_set_field64(EAS_END_DATA, new_eas.w, eisn);
     }
 
+    if (kvm_irqchip_in_kernel()) {
+        Error *local_err = NULL;
+
+        kvmppc_xive_set_source_config(xive, lisn, &new_eas, &local_err);
+        if (local_err) {
+            error_report_err(local_err);
+            return H_HARDWARE;
+        }
+    }
+
 out:
     xive->eat[lisn] = new_eas;
     return H_SUCCESS;
@@ -1103,6 +1129,16 @@ static target_ulong h_int_set_queue_config(PowerPCCPU 
*cpu,
      */
 
 out:
+    if (kvm_irqchip_in_kernel()) {
+        Error *local_err = NULL;
+
+        kvmppc_xive_set_queue_config(xive, end_blk, end_idx, &end, &local_err);
+        if (local_err) {
+            error_report_err(local_err);
+            return H_HARDWARE;
+        }
+    }
+
     /* Update END */
     memcpy(&xive->endt[end_idx], &end, sizeof(XiveEND));
     return H_SUCCESS;
@@ -1194,6 +1230,16 @@ static target_ulong h_int_get_queue_config(PowerPCCPU 
*cpu,
         args[2] = 0;
     }
 
+    if (kvm_irqchip_in_kernel()) {
+        Error *local_err = NULL;
+
+        kvmppc_xive_get_queue_config(xive, end_blk, end_idx, end, &local_err);
+        if (local_err) {
+            error_report_err(local_err);
+            return H_HARDWARE;
+        }
+    }
+
     /* TODO: do we need any locking on the END ? */
     if (flags & SPAPR_XIVE_END_DEBUG) {
         /* Load the event queue generation number into the return flags */
@@ -1346,15 +1392,20 @@ static target_ulong h_int_esb(PowerPCCPU *cpu,
         return H_P3;
     }
 
-    mmio_addr = xive->vc_base + xive_source_esb_mgmt(xsrc, lisn) + offset;
+    if (kvm_irqchip_in_kernel()) {
+        args[0] = kvmppc_xive_esb_rw(xsrc, lisn, offset, data,
+                                     flags & SPAPR_XIVE_ESB_STORE);
+    } else {
+        mmio_addr = xive->vc_base + xive_source_esb_mgmt(xsrc, lisn) + offset;
 
-    if (dma_memory_rw(&address_space_memory, mmio_addr, &data, 8,
-                      (flags & SPAPR_XIVE_ESB_STORE))) {
-        qemu_log_mask(LOG_GUEST_ERROR, "XIVE: failed to access ESB @0x%"
-                      HWADDR_PRIx "\n", mmio_addr);
-        return H_HARDWARE;
+        if (dma_memory_rw(&address_space_memory, mmio_addr, &data, 8,
+                          (flags & SPAPR_XIVE_ESB_STORE))) {
+            qemu_log_mask(LOG_GUEST_ERROR, "XIVE: failed to access ESB @0x%"
+                          HWADDR_PRIx "\n", mmio_addr);
+            return H_HARDWARE;
+        }
+        args[0] = (flags & SPAPR_XIVE_ESB_STORE) ? -1 : data;
     }
-    args[0] = (flags & SPAPR_XIVE_ESB_STORE) ? -1 : data;
     return H_SUCCESS;
 }
 
@@ -1411,7 +1462,20 @@ static target_ulong h_int_sync(PowerPCCPU *cpu,
      * This is not needed when running the emulation under QEMU
      */
 
-    /* This is not real hardware. Nothing to be done */
+    /*
+     * This is not real hardware. Nothing to be done unless when
+     * under KVM
+     */
+
+    if (kvm_irqchip_in_kernel()) {
+        Error *local_err = NULL;
+
+        kvmppc_xive_sync_source(xive, lisn, &local_err);
+        if (local_err) {
+            error_report_err(local_err);
+            return H_HARDWARE;
+        }
+    }
     return H_SUCCESS;
 }
 
@@ -1446,6 +1510,16 @@ static target_ulong h_int_reset(PowerPCCPU *cpu,
     }
 
     device_reset(DEVICE(xive));
+
+    if (kvm_irqchip_in_kernel()) {
+        Error *local_err = NULL;
+
+        kvmppc_xive_reset(xive, &local_err);
+        if (local_err) {
+            error_report_err(local_err);
+            return H_HARDWARE;
+        }
+    }
     return H_SUCCESS;
 }
 
diff --git a/hw/intc/spapr_xive_kvm.c b/hw/intc/spapr_xive_kvm.c
index 7d9e771e8a91..964bad0c23fb 100644
--- a/hw/intc/spapr_xive_kvm.c
+++ b/hw/intc/spapr_xive_kvm.c
@@ -89,6 +89,50 @@ void kvmppc_xive_cpu_connect(XiveTCTX *tctx, Error **errp)
  * XIVE Interrupt Source (KVM)
  */
 
+void kvmppc_xive_set_source_config(SpaprXive *xive, uint32_t lisn, XiveEAS 
*eas,
+                                   Error **errp)
+{
+    uint32_t end_idx;
+    uint32_t end_blk;
+    uint8_t priority;
+    uint32_t server;
+    bool masked;
+    uint32_t eisn;
+    uint64_t kvm_src;
+    Error *local_err = NULL;
+
+    assert(xive_eas_is_valid(eas));
+
+    end_idx = xive_get_field64(EAS_END_INDEX, eas->w);
+    end_blk = xive_get_field64(EAS_END_BLOCK, eas->w);
+    eisn = xive_get_field64(EAS_END_DATA, eas->w);
+    masked = xive_eas_is_masked(eas);
+
+    spapr_xive_end_to_target(end_blk, end_idx, &server, &priority);
+
+    kvm_src = priority << KVM_XIVE_SOURCE_PRIORITY_SHIFT &
+        KVM_XIVE_SOURCE_PRIORITY_MASK;
+    kvm_src |= server << KVM_XIVE_SOURCE_SERVER_SHIFT &
+        KVM_XIVE_SOURCE_SERVER_MASK;
+    kvm_src |= ((uint64_t) masked << KVM_XIVE_SOURCE_MASKED_SHIFT) &
+        KVM_XIVE_SOURCE_MASKED_MASK;
+    kvm_src |= ((uint64_t)eisn << KVM_XIVE_SOURCE_EISN_SHIFT) &
+        KVM_XIVE_SOURCE_EISN_MASK;
+
+    kvm_device_access(xive->fd, KVM_DEV_XIVE_GRP_SOURCE_CONFIG, lisn,
+                      &kvm_src, true, &local_err);
+    if (local_err) {
+        error_propagate(errp, local_err);
+        return;
+    }
+}
+
+void kvmppc_xive_sync_source(SpaprXive *xive, uint32_t lisn, Error **errp)
+{
+    kvm_device_access(xive->fd, KVM_DEV_XIVE_GRP_SOURCE_SYNC, lisn,
+                      NULL, true, errp);
+}
+
 /*
  * At reset, the interrupt sources are simply created and MASKED. We
  * only need to inform the KVM XIVE device about their type: LSI or
@@ -125,6 +169,64 @@ void kvmppc_xive_source_reset(XiveSource *xsrc, Error 
**errp)
     }
 }
 
+/*
+ * This is used to perform the magic loads on the ESB pages, described
+ * in xive.h.
+ *
+ * Memory barriers should not be needed for loads (no store for now).
+ */
+static uint64_t xive_esb_rw(XiveSource *xsrc, int srcno, uint32_t offset,
+                            uint64_t data, bool write)
+{
+    uint64_t *addr = xsrc->esb_mmap + xive_source_esb_mgmt(xsrc, srcno) +
+        offset;
+
+    if (write) {
+        *addr = cpu_to_be64(data);
+        return -1;
+    } else {
+        /* Prevent the compiler from optimizing away the load */
+        volatile uint64_t value = be64_to_cpu(*addr);
+        return value;
+    }
+}
+
+static uint8_t xive_esb_read(XiveSource *xsrc, int srcno, uint32_t offset)
+{
+    return xive_esb_rw(xsrc, srcno, offset, 0, 0) & 0x3;
+}
+
+static void xive_esb_trigger(XiveSource *xsrc, int srcno)
+{
+    uint64_t *addr = xsrc->esb_mmap + xive_source_esb_page(xsrc, srcno);
+
+    *addr = 0x0;
+}
+
+uint64_t kvmppc_xive_esb_rw(XiveSource *xsrc, int srcno, uint32_t offset,
+                            uint64_t data, bool write)
+{
+    if (write) {
+        return xive_esb_rw(xsrc, srcno, offset, data, 1);
+    }
+
+    /*
+     * Special Load EOI handling for LSI sources. Q bit is never set
+     * and the interrupt should be re-triggered if the level is still
+     * asserted.
+     */
+    if (xive_source_irq_is_lsi(xsrc, srcno) &&
+        offset == XIVE_ESB_LOAD_EOI) {
+        xive_esb_read(xsrc, srcno, XIVE_ESB_SET_PQ_00);
+        if (xsrc->status[srcno] & XIVE_STATUS_ASSERTED) {
+            xive_esb_trigger(xsrc, srcno);
+        }
+        return 0;
+    } else {
+        return xive_esb_rw(xsrc, srcno, offset, 0, 0);
+    }
+}
+
 void kvmppc_xive_source_set_irq(void *opaque, int srcno, int val)
 {
     XiveSource *xsrc = opaque;
@@ -155,6 +257,101 @@ void kvmppc_xive_source_set_irq(void *opaque, int srcno, 
int val)
 /*
  * sPAPR XIVE interrupt controller (KVM)
  */
+void kvmppc_xive_get_queue_config(SpaprXive *xive, uint8_t end_blk,
+                                  uint32_t end_idx, XiveEND *end,
+                                  Error **errp)
+{
+    struct kvm_ppc_xive_eq kvm_eq = { 0 };
+    uint64_t kvm_eq_idx;
+    uint8_t priority;
+    uint32_t server;
+    Error *local_err = NULL;
+
+    assert(xive_end_is_valid(end));
+
+    /* Encode the tuple (server, prio) as a KVM EQ index */
+    spapr_xive_end_to_target(end_blk, end_idx, &server, &priority);
+
+    kvm_eq_idx = priority << KVM_XIVE_EQ_PRIORITY_SHIFT &
+            KVM_XIVE_EQ_PRIORITY_MASK;
+    kvm_eq_idx |= server << KVM_XIVE_EQ_SERVER_SHIFT &
+        KVM_XIVE_EQ_SERVER_MASK;
+
+    kvm_device_access(xive->fd, KVM_DEV_XIVE_GRP_EQ_CONFIG, kvm_eq_idx,
+                      &kvm_eq, false, &local_err);
+    if (local_err) {
+        error_propagate(errp, local_err);
+        return;
+    }
+
+    /*
+     * The EQ index and toggle bit are updated by HW. These are the
+     * only fields from KVM we want to update QEMU with. The other END
+     * fields should already be in the QEMU END table.
+     */
+    end->w1 = xive_set_field32(END_W1_GENERATION, 0ul, kvm_eq.qtoggle) |
+        xive_set_field32(END_W1_PAGE_OFF, 0ul, kvm_eq.qindex);
+}
+
+void kvmppc_xive_set_queue_config(SpaprXive *xive, uint8_t end_blk,
+                                  uint32_t end_idx, XiveEND *end,
+                                  Error **errp)
+{
+    struct kvm_ppc_xive_eq kvm_eq = { 0 };
+    uint64_t kvm_eq_idx;
+    uint8_t priority;
+    uint32_t server;
+    Error *local_err = NULL;
+
+    /*
+     * Build the KVM state from the local END structure.
+     */
+
+    kvm_eq.flags = 0;
+    if (xive_get_field32(END_W0_UCOND_NOTIFY, end->w0)) {
+        kvm_eq.flags |= KVM_XIVE_EQ_ALWAYS_NOTIFY;
+    }
+
+    /*
+     * If the hcall is disabling the EQ, set the size and page address
+     * to zero. When migrating, only valid ENDs are taken into
+     * account.
+     */
+    if (xive_end_is_valid(end)) {
+        kvm_eq.qshift = xive_get_field32(END_W0_QSIZE, end->w0) + 12;
+        kvm_eq.qaddr  = xive_end_qaddr(end);
+        /*
+         * The EQ toggle bit and index should only be relevant when
+         * restoring the EQ state
+         */
+        kvm_eq.qtoggle = xive_get_field32(END_W1_GENERATION, end->w1);
+        kvm_eq.qindex  = xive_get_field32(END_W1_PAGE_OFF, end->w1);
+    } else {
+        kvm_eq.qshift = 0;
+        kvm_eq.qaddr  = 0;
+    }
+
+    /* Encode the tuple (server, prio) as a KVM EQ index */
+    spapr_xive_end_to_target(end_blk, end_idx, &server, &priority);
+
+    kvm_eq_idx = priority << KVM_XIVE_EQ_PRIORITY_SHIFT &
+            KVM_XIVE_EQ_PRIORITY_MASK;
+    kvm_eq_idx |= server << KVM_XIVE_EQ_SERVER_SHIFT &
+        KVM_XIVE_EQ_SERVER_MASK;
+
+    kvm_device_access(xive->fd, KVM_DEV_XIVE_GRP_EQ_CONFIG, kvm_eq_idx,
+                      &kvm_eq, true, &local_err);
+    if (local_err) {
+        error_propagate(errp, local_err);
+        return;
+    }
+}
+
+void kvmppc_xive_reset(SpaprXive *xive, Error **errp)
+{
+    kvm_device_access(xive->fd, KVM_DEV_XIVE_GRP_CTRL, KVM_DEV_XIVE_RESET,
+                      NULL, true, errp);
+}
 
 static void *kvmppc_xive_mmap(SpaprXive *xive, int pgoff, size_t len,
                               Error **errp)
-- 
2.20.1