Virtual hash page table handling on pSeries machine

On pSeries logical partitions, excepting the old POWER4-style full system
partitions, the guest does not have direct access to the hardware page
table.  Instead, the pagetable exists in hypervisor memory, and the guest
must manipulate it with hypercalls.

However, our current pSeries emulation more closely resembles the old
style where the guest must set up and handle the pagetables itself.  This
patch converts it to act like a modern partition.

This involves two things: first, the hash translation path is modified to
permit the has table to be stored externally to the emulated machine's
RAM.  The pSeries machine init code configures the CPUs to use this mode.

Secondly, we emulate the PAPR hypercalls for manipulating the external
hashed page table.

Signed-off-by: David Gibson <dwg@au1.ibm.com>
Signed-off-by: Alexander Graf <agraf@suse.de>

2 files changed, 285 insertions, 4 deletions

diff --git a/hw/spapr.c b/hw/spapr.c
index c24c92b1a0..57140d231d 100644
--- a/hw/spapr.c
+++ b/hw/spapr.c
@@ -52,12 +52,15 @@ static void *spapr_create_fdt(int *fdt_size, ram_addr_t ramsize,
                               sPAPREnvironment *spapr,
                               target_phys_addr_t initrd_base,
                               target_phys_addr_t initrd_size,
-                              const char *kernel_cmdline)
+                              const char *kernel_cmdline,
+                              long hash_shift)
 {
     void *fdt;
     uint64_t mem_reg_property[] = { 0, cpu_to_be64(ramsize) };
     uint32_t start_prop = cpu_to_be32(initrd_base);
     uint32_t end_prop = cpu_to_be32(initrd_base + initrd_size);
+    uint32_t pft_size_prop[] = {0, cpu_to_be32(hash_shift)};
+    char hypertas_prop[] = "hcall-pft\0hcall-term";
     int i;
     char *modelname;
     int ret;
@@ -145,6 +148,8 @@ static void *spapr_create_fdt(int *fdt_size, ram_addr_t ramsize,
          * full emu, for kvm we should copy it from the host */
         _FDT((fdt_property_cell(fdt, "clock-frequency", 1000000000)));
         _FDT((fdt_property_cell(fdt, "ibm,slb-size", env->slb_nr)));
+        _FDT((fdt_property(fdt, "ibm,pft-size",
+                           pft_size_prop, sizeof(pft_size_prop))));
         _FDT((fdt_property_string(fdt, "status", "okay")));
         _FDT((fdt_property(fdt, "64-bit", NULL, 0)));
 
@@ -160,6 +165,14 @@ static void *spapr_create_fdt(int *fdt_size, ram_addr_t ramsize,
 
     _FDT((fdt_end_node(fdt)));
 
+    /* RTAS */
+    _FDT((fdt_begin_node(fdt, "rtas")));
+
+    _FDT((fdt_property(fdt, "ibm,hypertas-functions", hypertas_prop,
+                       sizeof(hypertas_prop))));
+
+    _FDT((fdt_end_node(fdt)));
+
     /* vdevice */
     _FDT((fdt_begin_node(fdt, "vdevice")));
 
@@ -208,12 +221,13 @@ static void ppc_spapr_init(ram_addr_t ram_size,
                            const char *cpu_model)
 {
     CPUState *envs[MAX_CPUS];
-    void *fdt;
+    void *fdt, *htab;
     int i;
     ram_addr_t ram_offset;
     target_phys_addr_t fdt_addr;
     uint32_t kernel_base, initrd_base;
-    long kernel_size, initrd_size;
+    long kernel_size, initrd_size, htab_size;
+    long pteg_shift = 17;
     int fdt_size;
 
     spapr = qemu_malloc(sizeof(*spapr));
@@ -250,6 +264,18 @@ static void ppc_spapr_init(ram_addr_t ram_size,
     ram_offset = qemu_ram_alloc(NULL, "ppc_spapr.ram", ram_size);
     cpu_register_physical_memory(0, ram_size, ram_offset);
 
+    /* allocate hash page table.  For now we always make this 16mb,
+     * later we should probably make it scale to the size of guest
+     * RAM */
+    htab_size = 1ULL << (pteg_shift + 7);
+    htab = qemu_mallocz(htab_size);
+
+    for (i = 0; i < smp_cpus; i++) {
+        envs[i]->external_htab = htab;
+        envs[i]->htab_base = -1;
+        envs[i]->htab_mask = htab_size - 1;
+    }
+
     spapr->vio_bus = spapr_vio_bus_init();
 
     for (i = 0; i < MAX_SERIAL_PORTS; i++) {
@@ -296,7 +322,8 @@ static void ppc_spapr_init(ram_addr_t ram_size,
 
     /* Prepare the device tree */
     fdt = spapr_create_fdt(&fdt_size, ram_size, cpu_model, envs, spapr,
-                           initrd_base, initrd_size, kernel_cmdline);
+                           initrd_base, initrd_size, kernel_cmdline,
+                           pteg_shift + 7);
     assert(fdt != NULL);
 
     cpu_physical_memory_write(fdt_addr, fdt, fdt_size);
diff --git a/hw/spapr_hcall.c b/hw/spapr_hcall.c
index e3919d01c2..0ba17172da 100644
--- a/hw/spapr_hcall.c
+++ b/hw/spapr_hcall.c
@@ -1,8 +1,253 @@
 #include "sysemu.h"
 #include "cpu.h"
 #include "qemu-char.h"
+#include "sysemu.h"
+#include "qemu-char.h"
+#include "exec-all.h"
 #include "hw/spapr.h"
 
+#define HPTES_PER_GROUP 8
+
+#define HPTE_V_SSIZE_SHIFT      62
+#define HPTE_V_AVPN_SHIFT       7
+#define HPTE_V_AVPN             0x3fffffffffffff80ULL
+#define HPTE_V_AVPN_VAL(x)      (((x) & HPTE_V_AVPN) >> HPTE_V_AVPN_SHIFT)
+#define HPTE_V_COMPARE(x, y)    (!(((x) ^ (y)) & 0xffffffffffffff80UL))
+#define HPTE_V_BOLTED           0x0000000000000010ULL
+#define HPTE_V_LOCK             0x0000000000000008ULL
+#define HPTE_V_LARGE            0x0000000000000004ULL
+#define HPTE_V_SECONDARY        0x0000000000000002ULL
+#define HPTE_V_VALID            0x0000000000000001ULL
+
+#define HPTE_R_PP0              0x8000000000000000ULL
+#define HPTE_R_TS               0x4000000000000000ULL
+#define HPTE_R_KEY_HI           0x3000000000000000ULL
+#define HPTE_R_RPN_SHIFT        12
+#define HPTE_R_RPN              0x3ffffffffffff000ULL
+#define HPTE_R_FLAGS            0x00000000000003ffULL
+#define HPTE_R_PP               0x0000000000000003ULL
+#define HPTE_R_N                0x0000000000000004ULL
+#define HPTE_R_G                0x0000000000000008ULL
+#define HPTE_R_M                0x0000000000000010ULL
+#define HPTE_R_I                0x0000000000000020ULL
+#define HPTE_R_W                0x0000000000000040ULL
+#define HPTE_R_WIMG             0x0000000000000078ULL
+#define HPTE_R_C                0x0000000000000080ULL
+#define HPTE_R_R                0x0000000000000100ULL
+#define HPTE_R_KEY_LO           0x0000000000000e00ULL
+
+#define HPTE_V_1TB_SEG          0x4000000000000000ULL
+#define HPTE_V_VRMA_MASK        0x4001ffffff000000ULL
+
+#define HPTE_V_HVLOCK           0x40ULL
+
+static inline int lock_hpte(void *hpte, target_ulong bits)
+{
+    uint64_t pteh;
+
+    pteh = ldq_p(hpte);
+
+    /* We're protected by qemu's global lock here */
+    if (pteh & bits) {
+        return 0;
+    }
+    stq_p(hpte, pteh | HPTE_V_HVLOCK);
+    return 1;
+}
+
+static target_ulong compute_tlbie_rb(target_ulong v, target_ulong r,
+                                     target_ulong pte_index)
+{
+    target_ulong rb, va_low;
+
+    rb = (v & ~0x7fULL) << 16; /* AVA field */
+    va_low = pte_index >> 3;
+    if (v & HPTE_V_SECONDARY) {
+        va_low = ~va_low;
+    }
+    /* xor vsid from AVA */
+    if (!(v & HPTE_V_1TB_SEG)) {
+        va_low ^= v >> 12;
+    } else {
+        va_low ^= v >> 24;
+    }
+    va_low &= 0x7ff;
+    if (v & HPTE_V_LARGE) {
+        rb |= 1;                         /* L field */
+#if 0 /* Disable that P7 specific bit for now */
+        if (r & 0xff000) {
+            /* non-16MB large page, must be 64k */
+            /* (masks depend on page size) */
+            rb |= 0x1000;                /* page encoding in LP field */
+            rb |= (va_low & 0x7f) << 16; /* 7b of VA in AVA/LP field */
+            rb |= (va_low & 0xfe);       /* AVAL field */
+        }
+#endif
+    } else {
+        /* 4kB page */
+        rb |= (va_low & 0x7ff) << 12;   /* remaining 11b of AVA */
+    }
+    rb |= (v >> 54) & 0x300;            /* B field */
+    return rb;
+}
+
+static target_ulong h_enter(CPUState *env, sPAPREnvironment *spapr,
+                            target_ulong opcode, target_ulong *args)
+{
+    target_ulong flags = args[0];
+    target_ulong pte_index = args[1];
+    target_ulong pteh = args[2];
+    target_ulong ptel = args[3];
+    target_ulong porder;
+    target_ulong i, pa;
+    uint8_t *hpte;
+
+    /* only handle 4k and 16M pages for now */
+    porder = 12;
+    if (pteh & HPTE_V_LARGE) {
+#if 0 /* We don't support 64k pages yet */
+        if ((ptel & 0xf000) == 0x1000) {
+            /* 64k page */
+            porder = 16;
+        } else
+#endif
+        if ((ptel & 0xff000) == 0) {
+            /* 16M page */
+            porder = 24;
+            /* lowest AVA bit must be 0 for 16M pages */
+            if (pteh & 0x80) {
+                return H_PARAMETER;
+            }
+        } else {
+            return H_PARAMETER;
+        }
+    }
+
+    pa = ptel & HPTE_R_RPN;
+    /* FIXME: bounds check the pa? */
+
+    /* Check WIMG */
+    if ((ptel & HPTE_R_WIMG) != HPTE_R_M) {
+        return H_PARAMETER;
+    }
+    pteh &= ~0x60ULL;
+
+    if ((pte_index * HASH_PTE_SIZE_64) & ~env->htab_mask) {
+        return H_PARAMETER;
+    }
+    if (likely((flags & H_EXACT) == 0)) {
+        pte_index &= ~7ULL;
+        hpte = env->external_htab + (pte_index * HASH_PTE_SIZE_64);
+        for (i = 0; ; ++i) {
+            if (i == 8) {
+                return H_PTEG_FULL;
+            }
+            if (((ldq_p(hpte) & HPTE_V_VALID) == 0) &&
+                lock_hpte(hpte, HPTE_V_HVLOCK | HPTE_V_VALID)) {
+                break;
+            }
+            hpte += HASH_PTE_SIZE_64;
+        }
+    } else {
+        i = 0;
+        hpte = env->external_htab + (pte_index * HASH_PTE_SIZE_64);
+        if (!lock_hpte(hpte, HPTE_V_HVLOCK | HPTE_V_VALID)) {
+            return H_PTEG_FULL;
+        }
+    }
+    stq_p(hpte + (HASH_PTE_SIZE_64/2), ptel);
+    /* eieio();  FIXME: need some sort of barrier for smp? */
+    stq_p(hpte, pteh);
+
+    assert(!(ldq_p(hpte) & HPTE_V_HVLOCK));
+    args[0] = pte_index + i;
+    return H_SUCCESS;
+}
+
+static target_ulong h_remove(CPUState *env, sPAPREnvironment *spapr,
+                             target_ulong opcode, target_ulong *args)
+{
+    target_ulong flags = args[0];
+    target_ulong pte_index = args[1];
+    target_ulong avpn = args[2];
+    uint8_t *hpte;
+    target_ulong v, r, rb;
+
+    if ((pte_index * HASH_PTE_SIZE_64) & ~env->htab_mask) {
+        return H_PARAMETER;
+    }
+
+    hpte = env->external_htab + (pte_index * HASH_PTE_SIZE_64);
+    while (!lock_hpte(hpte, HPTE_V_HVLOCK)) {
+        /* We have no real concurrency in qemu soft-emulation, so we
+         * will never actually have a contested lock */
+        assert(0);
+    }
+
+    v = ldq_p(hpte);
+    r = ldq_p(hpte + (HASH_PTE_SIZE_64/2));
+
+    if ((v & HPTE_V_VALID) == 0 ||
+        ((flags & H_AVPN) && (v & ~0x7fULL) != avpn) ||
+        ((flags & H_ANDCOND) && (v & avpn) != 0)) {
+        stq_p(hpte, v & ~HPTE_V_HVLOCK);
+        assert(!(ldq_p(hpte) & HPTE_V_HVLOCK));
+        return H_NOT_FOUND;
+    }
+    args[0] = v & ~HPTE_V_HVLOCK;
+    args[1] = r;
+    stq_p(hpte, 0);
+    rb = compute_tlbie_rb(v, r, pte_index);
+    ppc_tlb_invalidate_one(env, rb);
+    assert(!(ldq_p(hpte) & HPTE_V_HVLOCK));
+    return H_SUCCESS;
+}
+
+static target_ulong h_protect(CPUState *env, sPAPREnvironment *spapr,
+                              target_ulong opcode, target_ulong *args)
+{
+    target_ulong flags = args[0];
+    target_ulong pte_index = args[1];
+    target_ulong avpn = args[2];
+    uint8_t *hpte;
+    target_ulong v, r, rb;
+
+    if ((pte_index * HASH_PTE_SIZE_64) & ~env->htab_mask) {
+        return H_PARAMETER;
+    }
+
+    hpte = env->external_htab + (pte_index * HASH_PTE_SIZE_64);
+    while (!lock_hpte(hpte, HPTE_V_HVLOCK)) {
+        /* We have no real concurrency in qemu soft-emulation, so we
+         * will never actually have a contested lock */
+        assert(0);
+    }
+
+    v = ldq_p(hpte);
+    r = ldq_p(hpte + (HASH_PTE_SIZE_64/2));
+
+    if ((v & HPTE_V_VALID) == 0 ||
+        ((flags & H_AVPN) && (v & ~0x7fULL) != avpn)) {
+        stq_p(hpte, v & ~HPTE_V_HVLOCK);
+        assert(!(ldq_p(hpte) & HPTE_V_HVLOCK));
+        return H_NOT_FOUND;
+    }
+
+    r &= ~(HPTE_R_PP0 | HPTE_R_PP | HPTE_R_N |
+           HPTE_R_KEY_HI | HPTE_R_KEY_LO);
+    r |= (flags << 55) & HPTE_R_PP0;
+    r |= (flags << 48) & HPTE_R_KEY_HI;
+    r |= flags & (HPTE_R_PP | HPTE_R_N | HPTE_R_KEY_LO);
+    rb = compute_tlbie_rb(v, r, pte_index);
+    stq_p(hpte, v & ~HPTE_V_VALID);
+    ppc_tlb_invalidate_one(env, rb);
+    stq_p(hpte + (HASH_PTE_SIZE_64/2), r);
+    /* Don't need a memory barrier, due to qemu's global lock */
+    stq_p(hpte, v & ~HPTE_V_HVLOCK);
+    assert(!(ldq_p(hpte) & HPTE_V_HVLOCK));
+    return H_SUCCESS;
+}
+
 spapr_hcall_fn hypercall_table[(MAX_HCALL_OPCODE / 4) + 1];
 
 void spapr_register_hypercall(target_ulong opcode, spapr_hcall_fn fn)
@@ -39,3 +284,12 @@ target_ulong spapr_hypercall(CPUState *env, target_ulong opcode,
     hcall_dprintf("Unimplemented hcall 0x" TARGET_FMT_lx "\n", opcode);
     return H_FUNCTION;
 }
+
+static void hypercall_init(void)
+{
+    /* hcall-pft */
+    spapr_register_hypercall(H_ENTER, h_enter);
+    spapr_register_hypercall(H_REMOVE, h_remove);
+    spapr_register_hypercall(H_PROTECT, h_protect);
+}
+device_init(hypercall_init);