On 2/17/25 12:49, Aditya Gupta wrote:
SBE's implementation of S0 seems to be basically "stop all clocks" and
then "host reset"
Nearest equivalent to the stop clocks seems to be 'pause_all_vcpus' in
QEMU,
Then reset the host, which is 'SHUTDOWN_CAUSE_GUEST_RESET' in QEMU.
Implement the S0 interrupt as pause_vcpus + guest_reset
See 'stopClocksS0' in SBE source code for more information.
Signed-off-by: Aditya Gupta <adit...@linux.ibm.com>
---
hw/ppc/pnv_sbe.c | 50 +++++++++++++++++++++++++++++++++++++++---------
1 file changed, 41 insertions(+), 9 deletions(-)
diff --git a/hw/ppc/pnv_sbe.c b/hw/ppc/pnv_sbe.c
index 62c94a04a2df..a6bf13650f2d 100644
--- a/hw/ppc/pnv_sbe.c
+++ b/hw/ppc/pnv_sbe.c
@@ -21,6 +21,8 @@
#include "qapi/error.h"
#include "qemu/log.h"
#include "qemu/module.h"
+#include "system/cpus.h"
+#include "system/runstate.h"
#include "hw/irq.h"
#include "hw/qdev-properties.h"
#include "hw/ppc/pnv.h"
@@ -80,6 +82,15 @@
#define SBE_CONTROL_REG_S0 PPC_BIT(14)
#define SBE_CONTROL_REG_S1 PPC_BIT(15)
+static void pnv_sbe_set_host_doorbell(PnvSBE *sbe, uint64_t val)
+{
+ val &= SBE_HOST_RESPONSE_MASK; /* Is this right? What does HW do? */
+ sbe->host_doorbell = val;
+
+ trace_pnv_sbe_reg_set_host_doorbell(val);
+ qemu_set_irq(sbe->psi_irq, !!val);
+}
+
struct sbe_msg {
uint64_t reg[4];
};
@@ -104,6 +115,7 @@ static uint64_t pnv_sbe_power9_xscom_ctrl_read(void
*opaque, hwaddr addr,
static void pnv_sbe_power9_xscom_ctrl_write(void *opaque, hwaddr addr,
uint64_t val, unsigned size)
{
+ PnvSBE *sbe = opaque;
uint32_t offset = addr >> 3;
trace_pnv_sbe_xscom_ctrl_write(addr, val);
@@ -113,6 +125,35 @@ static void pnv_sbe_power9_xscom_ctrl_write(void *opaque,
hwaddr addr,
switch (val) {
case SBE_CONTROL_REG_S0:
qemu_log_mask(LOG_UNIMP, "SBE: S0 Interrupt triggered\n");
+
+ pnv_sbe_set_host_doorbell(sbe, sbe->host_doorbell |
SBE_HOST_RESPONSE_MASK);
+
+ /*
+ * Looks like, SBE stops clocks for all cores in S0.
+ * See 'stopClocksS0' in SBE source code.
+ * Nearest equivalent in QEMU seems to be 'pause_all_vcpus'
+ */
+ pause_all_vcpus();
+
+ /*
+ * TODO: Pass `mpipl` node in device tree to signify next
+ * boot is an MPIPL boot
+ */
+
+ /* Then do a guest reset */
+ /*
+ * Requirement:
+ * This guest reset should not clear the memory (which is
+ * the case when this is merged)
This comment may need a rephrase. Also, if we are keeping an assumption
that SHUTDOWN_CAUSE_GUEST_RESET should not clear the memory, it may be
better to put a comment about this wherever it is handled as well.
+ */
+ qemu_system_reset_request(SHUTDOWN_CAUSE_GUEST_RESET);
+
+ /*
+ * XXX: Does SBE really do system reset or only stop
+ * clocks ? OPAL seems to think that control will not come
+ * to it after it has triggered S0 interrupt.
+ */
+
break;
case SBE_CONTROL_REG_S1:
qemu_log_mask(LOG_UNIMP, "SBE: S1 Interrupt triggered\n");
@@ -138,15 +179,6 @@ static const MemoryRegionOps pnv_sbe_power9_xscom_ctrl_ops
= {
.endianness = DEVICE_BIG_ENDIAN,
};
-static void pnv_sbe_set_host_doorbell(PnvSBE *sbe, uint64_t val)
-{
- val &= SBE_HOST_RESPONSE_MASK; /* Is this right? What does HW do? */
- sbe->host_doorbell = val;
-
- trace_pnv_sbe_reg_set_host_doorbell(val);
- qemu_set_irq(sbe->psi_irq, !!val);
-}
-
Code movement like above could be a separate patch, not necessary though.
Patch 1 can be squashed with this one.
Thanks
Harsh
/* SBE Target Type */
#define SBE_TARGET_TYPE_PROC 0x00
#define SBE_TARGET_TYPE_EX 0x01
