[PULL 01/35] target/ppc: Generate storage interrupts for radix RC changes

[Cédric Le Goater]

From: Shawn Anastasio <sanastasio@raptorengineering.com>

Change radix model to always generate a storage interrupt when the R/C
bits are not set appropriately in a PTE instead of setting the bits
itself.  According to the ISA both behaviors are valid, but in practice
this change more closely matches behavior observed on the POWER9 CPU.

>From the POWER9 Processor User's Manual, Section 4.10.13.1: "When
performing Radix translation, the POWER9 hardware triggers the
appropriate interrupt ... for the mode and type of access whenever
Reference (R) and Change (C) bits require setting in either the guest or
host page-table entry (PTE)."

Signed-off-by: Shawn Anastasio <sanastasio@raptorengineering.com>
Reviewed-by: Cédric Le Goater <clg@kaod.org>
Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Cédric Le Goater <clg@kaod.org>
---
 target/ppc/mmu-radix64.c | 74 ++++++++++++++++++++++++++--------------
 1 file changed, 49 insertions(+), 25 deletions(-)

diff --git a/target/ppc/mmu-radix64.c b/target/ppc/mmu-radix64.c
index 920084bd8ff2..5823e039e64f 100644
--- a/target/ppc/mmu-radix64.c
+++ b/target/ppc/mmu-radix64.c
@@ -219,27 +219,25 @@ static bool ppc_radix64_check_prot(PowerPCCPU *cpu, 
MMUAccessType access_type,
     return false;
 }
 
-static void ppc_radix64_set_rc(PowerPCCPU *cpu, MMUAccessType access_type,
-                               uint64_t pte, hwaddr pte_addr, int *prot)
+static int ppc_radix64_check_rc(MMUAccessType access_type, uint64_t pte)
 {
-    CPUState *cs = CPU(cpu);
-    uint64_t npte;
-
-    npte = pte | R_PTE_R; /* Always set reference bit */
+    switch (access_type) {
+    case MMU_DATA_STORE:
+        if (!(pte & R_PTE_C)) {
+            break;
+        }
+        /* fall through */
+    case MMU_INST_FETCH:
+    case MMU_DATA_LOAD:
+        if (!(pte & R_PTE_R)) {
+            break;
+        }
 
-    if (access_type == MMU_DATA_STORE) { /* Store/Write */
-        npte |= R_PTE_C; /* Set change bit */
-    } else {
-        /*
-         * Treat the page as read-only for now, so that a later write
-         * will pass through this function again to set the C bit.
-         */
-        *prot &= ~PAGE_WRITE;
+        /* R/C bits are already set appropriately for this access */
+        return 0;
     }
 
-    if (pte ^ npte) { /* If pte has changed then write it back */
-        stq_phys(cs->as, pte_addr, npte);
-    }
+    return 1;
 }
 
 static bool ppc_radix64_is_valid_level(int level, int psize, uint64_t nls)
@@ -380,7 +378,8 @@ static int ppc_radix64_partition_scoped_xlate(PowerPCCPU 
*cpu,
                                               ppc_v3_pate_t pate,
                                               hwaddr *h_raddr, int *h_prot,
                                               int *h_page_size, bool pde_addr,
-                                              int mmu_idx, bool guest_visible)
+                                              int mmu_idx, uint64_t lpid,
+                                              bool guest_visible)
 {
     MMUAccessType access_type = orig_access_type;
     int fault_cause = 0;
@@ -418,7 +417,24 @@ static int ppc_radix64_partition_scoped_xlate(PowerPCCPU 
*cpu,
     }
 
     if (guest_visible) {
-        ppc_radix64_set_rc(cpu, access_type, pte, pte_addr, h_prot);
+        if (ppc_radix64_check_rc(access_type, pte)) {
+            /*
+             * Per ISA 3.1 Book III, 7.5.3 and 7.5.5, failure to set R/C during
+             * partition-scoped translation when effLPID = 0 results in normal
+             * (non-Hypervisor) Data and Instruction Storage Interrupts
+             * respectively.
+             *
+             * ISA 3.0 is ambiguous about this, but tests on POWER9 hardware
+             * seem to exhibit the same behavior.
+             */
+            if (lpid > 0) {
+                ppc_radix64_raise_hsi(cpu, access_type, eaddr, g_raddr,
+                                      DSISR_ATOMIC_RC);
+            } else {
+                ppc_radix64_raise_si(cpu, access_type, eaddr, DSISR_ATOMIC_RC);
+            }
+            return 1;
+        }
     }
 
     return 0;
@@ -447,7 +463,8 @@ static int ppc_radix64_process_scoped_xlate(PowerPCCPU *cpu,
                                             vaddr eaddr, uint64_t pid,
                                             ppc_v3_pate_t pate, hwaddr 
*g_raddr,
                                             int *g_prot, int *g_page_size,
-                                            int mmu_idx, bool guest_visible)
+                                            int mmu_idx, uint64_t lpid,
+                                            bool guest_visible)
 {
     CPUState *cs = CPU(cpu);
     CPUPPCState *env = &cpu->env;
@@ -497,7 +514,7 @@ static int ppc_radix64_process_scoped_xlate(PowerPCCPU *cpu,
         ret = ppc_radix64_partition_scoped_xlate(cpu, access_type, eaddr,
                                                  prtbe_addr, pate, &h_raddr,
                                                  &h_prot, &h_page_size, true,
-                                                 5, guest_visible);
+                                                 5, lpid, guest_visible);
         if (ret) {
             return ret;
         }
@@ -539,7 +556,8 @@ static int ppc_radix64_process_scoped_xlate(PowerPCCPU *cpu,
             ret = ppc_radix64_partition_scoped_xlate(cpu, access_type, eaddr,
                                                      pte_addr, pate, &h_raddr,
                                                      &h_prot, &h_page_size,
-                                                     true, 5, guest_visible);
+                                                     true, 5, lpid,
+                                                     guest_visible);
             if (ret) {
                 return ret;
             }
@@ -580,7 +598,11 @@ static int ppc_radix64_process_scoped_xlate(PowerPCCPU 
*cpu,
     }
 
     if (guest_visible) {
-        ppc_radix64_set_rc(cpu, access_type, pte, pte_addr, g_prot);
+        /* R/C bits not appropriately set for access */
+        if (ppc_radix64_check_rc(access_type, pte)) {
+            ppc_radix64_raise_si(cpu, access_type, eaddr, DSISR_ATOMIC_RC);
+            return 1;
+        }
     }
 
     return 0;
@@ -695,7 +717,8 @@ static bool ppc_radix64_xlate_impl(PowerPCCPU *cpu, vaddr 
eaddr,
     if (relocation) {
         int ret = ppc_radix64_process_scoped_xlate(cpu, access_type, eaddr, 
pid,
                                                    pate, &g_raddr, &prot,
-                                                   &psize, mmu_idx, 
guest_visible);
+                                                   &psize, mmu_idx, lpid,
+                                                   guest_visible);
         if (ret) {
             return false;
         }
@@ -719,7 +742,8 @@ static bool ppc_radix64_xlate_impl(PowerPCCPU *cpu, vaddr 
eaddr,
             ret = ppc_radix64_partition_scoped_xlate(cpu, access_type, eaddr,
                                                      g_raddr, pate, raddr,
                                                      &prot, &psize, false,
-                                                     mmu_idx, guest_visible);
+                                                     mmu_idx, lpid,
+                                                     guest_visible);
             if (ret) {
                 return false;
             }
-- 
2.41.0