xen/arm64: Added handling of the trapped access to OSLSR register

Linux/dom0 accesses OSLSR register when saving CPU context during the
suspend procedure. Xen traps access to this register, but has no handling
for it. Consequently, Xen injects undef exception to linux, causing it to
crash. This patch adds handling of the trapped access to OSLSR as read
only as a fixed value.

For convenience, introduce a new helper handle_ro_read_val() based on
handle_ro_raz() that will return a specified value on read and
re-implement handle_ro_raz() based on the new helper.

Signed-off-by: Mirela Simonovic <mirela.simonovic@aggios.com>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
Acked-by: Julien Grall <julien.grall@arm.com>
[julien: Add a word about the new helper]

diff --git a/xen/arch/arm/arm64/vsysreg.c b/xen/arch/arm/arm64/vsysreg.c
index c57ac1250350cdf53742d985f1d89ebae9061923..6e6082457236ef8a61d591caa1aa6c93dced457d 100644 (file)
--- a/xen/arch/arm/arm64/vsysreg.c
+++ b/xen/arch/arm/arm64/vsysreg.c
@@ -57,13 +57,15 @@ void do_sysreg(struct cpu_user_regs *regs,
      * ARMv8 (DDI 0487A.d): D1-1509 Table D1-58
      *
      * Unhandled:
-     *    OSLSR_EL1
      *    DBGPRCR_EL1
      */
     case HSR_SYSREG_OSLAR_EL1:
         return handle_wo_wi(regs, regidx, hsr.sysreg.read, hsr, 1);
     case HSR_SYSREG_OSDLR_EL1:
         return handle_raz_wi(regs, regidx, hsr.sysreg.read, hsr, 1);
+    case HSR_SYSREG_OSLSR_EL1:
+        return handle_ro_read_val(regs, regidx, hsr.sysreg.read, hsr, 1,
+                                  1 << 3);
 
     /*
      * MDCR_EL2.TDA

diff --git a/xen/arch/arm/traps.c b/xen/arch/arm/traps.c
index 5c18e918b0e10df19969fecadb1bc74e6b517334..d71adfa745a32744190549df709b03c9231208a9 100644 (file)
--- a/xen/arch/arm/traps.c
+++ b/xen/arch/arm/traps.c
@@ -1739,12 +1739,13 @@ void handle_wo_wi(struct cpu_user_regs *regs,
     advance_pc(regs, hsr);
 }
 
-/* Read only as read as zero */
-void handle_ro_raz(struct cpu_user_regs *regs,
-                   int regidx,
-                   bool read,
-                   const union hsr hsr,
-                   int min_el)
+/* Read only as value provided with 'val' argument of this function */
+void handle_ro_read_val(struct cpu_user_regs *regs,
+                        int regidx,
+                        bool read,
+                        const union hsr hsr,
+                        int min_el,
+                        register_t val)
 {
     ASSERT((min_el == 0) || (min_el == 1));
 
@@ -1753,13 +1754,22 @@ void handle_ro_raz(struct cpu_user_regs *regs,
 
     if ( !read )
         return inject_undef_exception(regs, hsr);
-    /* else: raz */
 
-    set_user_reg(regs, regidx, 0);
+    set_user_reg(regs, regidx, val);
 
     advance_pc(regs, hsr);
 }
 
+/* Read only as read as zero */
+inline void handle_ro_raz(struct cpu_user_regs *regs,
+                          int regidx,
+                          bool read,
+                          const union hsr hsr,
+                          int min_el)
+{
+    handle_ro_read_val(regs, regidx, read, hsr, min_el, 0);
+}
+
 void dump_guest_s1_walk(struct domain *d, vaddr_t addr)
 {
     register_t ttbcr = READ_SYSREG(TCR_EL1);

diff --git a/xen/include/asm-arm/traps.h b/xen/include/asm-arm/traps.h
index a0e5e92ebb1a6c2029a9b26b9a3684bc22449042..70b52d1d1662984b57346f8dd357599074175f2c 100644 (file)
--- a/xen/include/asm-arm/traps.h
+++ b/xen/include/asm-arm/traps.h
@@ -27,6 +27,10 @@ void handle_wo_wi(struct cpu_user_regs *regs, int regidx, bool read,
 void handle_ro_raz(struct cpu_user_regs *regs, int regidx, bool read,
                    const union hsr hsr, int min_el);
 
+/* Read only as value provided with 'val' argument */
+void handle_ro_read_val(struct cpu_user_regs *regs, int regidx, bool read,
+                        const union hsr hsr, int min_el, register_t val);
+
 /* Co-processor registers emulation (see arch/arm/vcpreg.c). */
 void do_cp15_32(struct cpu_user_regs *regs, const union hsr hsr);
 void do_cp15_64(struct cpu_user_regs *regs, const union hsr hsr);