Merge tag 'pull-riscv-to-apply-20240110' of https://github.com/alistair23/qemu into staging

RISC-V PR for 9.0

* Make vector whole-register move (vmv) depend on vtype register
* Fix th.dcache.cval1 priviledge check
* Don't allow write mstatus_vs without RVV
* Use hwaddr instead of target_ulong for RV32
* Fix machine IDs QOM getters\
* Fix KVM reg id sizes
* ACPI: Enable AIA, PLIC and update RHCT
* Fix the interrupts-extended property format of PLIC
* Add support for Zacas extension
* Add amocas.[w,d,q] instructions
* Document acpi parameter of virt machine
* RVA22 profiles support
* Remove group setting of KVM AIA if the machine only has 1 socket
* Add RVV CSRs to KVM
* sifive_u: Update S-mode U-Boot image build instructions
* Upgrade OpenSBI from v1.3.1 to v1.4
* pmp: Ignore writes when RW=01 and MML=0
* Assert that the CSR numbers will be correct
* Don't adjust vscause for exceptions
* Ensure mideleg is set correctly on reset

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# gpg: Signature made Wed 10 Jan 2024 08:56:41 GMT
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# gpg: WARNING: This key is not certified with a trusted signature!
# gpg:          There is no indication that the signature belongs to the owner.
# Primary key fingerprint: 6AE9 02B6 A7CA 877D 6D65  9296 AF7C 9513 0C53 8013

* tag 'pull-riscv-to-apply-20240110' of https://github.com/alistair23/qemu: (65 commits)
  target/riscv: Ensure mideleg is set correctly on reset
  target/riscv: Don't adjust vscause for exceptions
  target/riscv: Assert that the CSR numbers will be correct
  target/riscv: pmp: Ignore writes when RW=01 and MML=0
  roms/opensbi: Upgrade from v1.3.1 to v1.4
  docs/system/riscv: sifive_u: Update S-mode U-Boot image build instructions
  target/riscv/kvm: add RVV and Vector CSR regs
  target/riscv/kvm: do PR_RISCV_V_SET_CONTROL during realize()
  linux-headers: riscv: add ptrace.h
  linux-headers: Update to Linux v6.7-rc5
  target/riscv/kvm.c: remove group setting of KVM AIA if the machine only has 1 socket
  target/riscv: add rva22s64 cpu
  target/riscv: add RVA22S64 profile
  target/riscv: add 'parent' in profile description
  target/riscv: add satp_mode profile support
  target/riscv/cpu.c: add riscv_cpu_is_32bit()
  target/riscv/cpu.c: finalize satp_mode earlier
  target/riscv: add priv ver restriction to profiles
  target/riscv: implement svade
  target/riscv: add 'rva22u64' CPU
  ...

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
diff --git a/include/qemu/fifo8.h b/include/qemu/fifo8.h
index 16be02f..c6295c6 100644
--- a/include/qemu/fifo8.h
+++ b/include/qemu/fifo8.h
@@ -71,7 +71,7 @@
  * fifo8_pop_buf:
  * @fifo: FIFO to pop from
  * @max: maximum number of bytes to pop
- * @num: actual number of returned bytes
+ * @numptr: pointer filled with number of bytes returned (can be NULL)
  *
  * Pop a number of elements from the FIFO up to a maximum of max. The buffer
  * containing the popped data is returned. This buffer points directly into
@@ -82,16 +82,43 @@
  * around in the ring buffer; in this case only a contiguous part of the data
  * is returned.
  *
- * The number of valid bytes returned is populated in *num; will always return
- * at least 1 byte. max must not be 0 or greater than the number of bytes in
- * the FIFO.
+ * The number of valid bytes returned is populated in *numptr; will always
+ * return at least 1 byte. max must not be 0 or greater than the number of
+ * bytes in the FIFO.
  *
  * Clients are responsible for checking the availability of requested data
  * using fifo8_num_used().
  *
  * Returns: A pointer to popped data.
  */
-const uint8_t *fifo8_pop_buf(Fifo8 *fifo, uint32_t max, uint32_t *num);
+const uint8_t *fifo8_pop_buf(Fifo8 *fifo, uint32_t max, uint32_t *numptr);
+
+/**
+ * fifo8_peek_buf: read upto max bytes from the fifo
+ * @fifo: FIFO to read from
+ * @max: maximum number of bytes to peek
+ * @numptr: pointer filled with number of bytes returned (can be NULL)
+ *
+ * Peek into a number of elements from the FIFO up to a maximum of max.
+ * The buffer containing the data peeked into is returned. This buffer points
+ * directly into the FIFO backing store. Since data is invalidated once any
+ * of the fifo8_* APIs are called on the FIFO, it is the caller responsibility
+ * to access it before doing further API calls.
+ *
+ * The function may return fewer bytes than requested when the data wraps
+ * around in the ring buffer; in this case only a contiguous part of the data
+ * is returned.
+ *
+ * The number of valid bytes returned is populated in *numptr; will always
+ * return at least 1 byte. max must not be 0 or greater than the number of
+ * bytes in the FIFO.
+ *
+ * Clients are responsible for checking the availability of requested data
+ * using fifo8_num_used().
+ *
+ * Returns: A pointer to peekable data.
+ */
+const uint8_t *fifo8_peek_buf(Fifo8 *fifo, uint32_t max, uint32_t *numptr);
 
 /**
  * fifo8_reset:
diff --git a/util/fifo8.c b/util/fifo8.c
index de8fd0f..4e01b53 100644
--- a/util/fifo8.c
+++ b/util/fifo8.c
@@ -66,19 +66,37 @@
     return ret;
 }
 
-const uint8_t *fifo8_pop_buf(Fifo8 *fifo, uint32_t max, uint32_t *num)
+static const uint8_t *fifo8_peekpop_buf(Fifo8 *fifo, uint32_t max,
+                                        uint32_t *numptr, bool do_pop)
 {
     uint8_t *ret;
+    uint32_t num;
 
     assert(max > 0 && max <= fifo->num);
-    *num = MIN(fifo->capacity - fifo->head, max);
+    num = MIN(fifo->capacity - fifo->head, max);
     ret = &fifo->data[fifo->head];
-    fifo->head += *num;
-    fifo->head %= fifo->capacity;
-    fifo->num -= *num;
+
+    if (do_pop) {
+        fifo->head += num;
+        fifo->head %= fifo->capacity;
+        fifo->num -= num;
+    }
+    if (numptr) {
+        *numptr = num;
+    }
     return ret;
 }
 
+const uint8_t *fifo8_peek_buf(Fifo8 *fifo, uint32_t max, uint32_t *numptr)
+{
+    return fifo8_peekpop_buf(fifo, max, numptr, false);
+}
+
+const uint8_t *fifo8_pop_buf(Fifo8 *fifo, uint32_t max, uint32_t *numptr)
+{
+    return fifo8_peekpop_buf(fifo, max, numptr, true);
+}
+
 void fifo8_reset(Fifo8 *fifo)
 {
     fifo->num = 0;