[xen staging] RISCV/shutdown: Implement machine_{halt,restart}()

[patchbot@xxxxxxx]

commit 6471badeeec92db1cb8155066551f7509cd82efd
Author:     Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
AuthorDate: Tue Sep 3 15:01:20 2024 +0100
Commit:     Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
CommitDate: Wed Sep 4 11:27:50 2024 +0100

    RISCV/shutdown: Implement machine_{halt,restart}()
    
    SBI has an API for shutdown so wire it up.  However, the spec does allow the
    call not to be implemented, so we have to cope with sbi_shutdown() 
returning.
    
    There is a reboot-capable SBI extention, but in the short term route
    machine_restart() into machine_halt().
    
    Then, use use machine_halt() rather than an infinite loop at the end of
    start_xen().  This avoids the Qemu smoke test needing to wait for the full
    timeout in order to succeed.
    
    Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
    Acked-by: Jan Beulich <jbeulich@xxxxxxxx>
    Reviewed-by: Oleksii Kurochko <oleksii.kurochko@xxxxxxxxx>
---
 xen/arch/riscv/Makefile          |  1 +
 xen/arch/riscv/include/asm/sbi.h |  3 +++
 xen/arch/riscv/sbi.c             |  5 +++++
 xen/arch/riscv/setup.c           |  6 ++----
 xen/arch/riscv/shutdown.c        | 27 +++++++++++++++++++++++++++
 xen/arch/riscv/stubs.c           | 12 ------------
 6 files changed, 38 insertions(+), 16 deletions(-)

diff --git a/xen/arch/riscv/Makefile b/xen/arch/riscv/Makefile
index 81b77b13d6..d192be7b55 100644
--- a/xen/arch/riscv/Makefile
+++ b/xen/arch/riscv/Makefile
@@ -4,6 +4,7 @@ obj-y += mm.o
 obj-$(CONFIG_RISCV_64) += riscv64/
 obj-y += sbi.o
 obj-y += setup.o
+obj-y += shutdown.o
 obj-y += stubs.o
 obj-y += traps.o
 obj-y += vm_event.o
diff --git a/xen/arch/riscv/include/asm/sbi.h b/xen/arch/riscv/include/asm/sbi.h
index 0e6820a4ed..4d72a2295e 100644
--- a/xen/arch/riscv/include/asm/sbi.h
+++ b/xen/arch/riscv/include/asm/sbi.h
@@ -13,6 +13,7 @@
 #define __ASM_RISCV_SBI_H__
 
 #define SBI_EXT_0_1_CONSOLE_PUTCHAR            0x1
+#define SBI_EXT_0_1_SHUTDOWN                   0x8
 
 struct sbiret {
     long error;
@@ -31,4 +32,6 @@ struct sbiret sbi_ecall(unsigned long ext, unsigned long fid,
  */
 void sbi_console_putchar(int ch);
 
+void sbi_shutdown(void);
+
 #endif /* __ASM_RISCV_SBI_H__ */
diff --git a/xen/arch/riscv/sbi.c b/xen/arch/riscv/sbi.c
index 0ae166c861..c7984344bc 100644
--- a/xen/arch/riscv/sbi.c
+++ b/xen/arch/riscv/sbi.c
@@ -42,3 +42,8 @@ void sbi_console_putchar(int ch)
 {
     sbi_ecall(SBI_EXT_0_1_CONSOLE_PUTCHAR, 0, ch, 0, 0, 0, 0, 0);
 }
+
+void sbi_shutdown(void)
+{
+    sbi_ecall(SBI_EXT_0_1_SHUTDOWN, 0, 0, 0, 0, 0, 0, 0);
+}
diff --git a/xen/arch/riscv/setup.c b/xen/arch/riscv/setup.c
index a6a29a1508..bf9078f36a 100644
--- a/xen/arch/riscv/setup.c
+++ b/xen/arch/riscv/setup.c
@@ -4,6 +4,7 @@
 #include <xen/compile.h>
 #include <xen/init.h>
 #include <xen/mm.h>
+#include <xen/shutdown.h>
 
 #include <public/version.h>
 
@@ -28,8 +29,5 @@ void __init noreturn start_xen(unsigned long bootcpu_id,
 
     printk("All set up\n");
 
-    for ( ;; )
-        asm volatile ("wfi");
-
-    unreachable();
+    machine_halt();
 }
diff --git a/xen/arch/riscv/shutdown.c b/xen/arch/riscv/shutdown.c
new file mode 100644
index 0000000000..3513d9af47
--- /dev/null
+++ b/xen/arch/riscv/shutdown.c
@@ -0,0 +1,27 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+#include <xen/shutdown.h>
+
+#include <asm/sbi.h>
+
+void machine_halt(void)
+{
+    sbi_shutdown();
+
+    /* TODO: Cope with sbi_shutdown() not being implemented. */
+
+    for ( ;; )
+        asm volatile ( "wfi" );
+
+    unreachable();
+}
+
+void machine_restart(unsigned int delay_millisecs)
+{
+    /*
+     * TODO: mdelay(delay_millisecs)
+     * TODO: Probe for #SRST support, where sbi_system_reset() has a
+     *       shutdown/reboot parameter.
+     */
+
+    machine_halt();
+}
diff --git a/xen/arch/riscv/stubs.c b/xen/arch/riscv/stubs.c
index 3285d18899..2aa245f272 100644
--- a/xen/arch/riscv/stubs.c
+++ b/xen/arch/riscv/stubs.c
@@ -49,18 +49,6 @@ void domain_set_time_offset(struct domain *d, int64_t 
time_offset_seconds)
     BUG_ON("unimplemented");
 }
 
-/* shutdown.c */
-
-void machine_restart(unsigned int delay_millisecs)
-{
-    BUG_ON("unimplemented");
-}
-
-void machine_halt(void)
-{
-    BUG_ON("unimplemented");
-}
-
 /* domctl.c */
 
 long arch_do_domctl(struct xen_domctl *domctl, struct domain *d,
--
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