The IRS has multiple ISTs, for different contexts:
 * physical LPIs (separately for each interrupt domain)
 * virtual LPIs
 * virtual SPIs

The config information for physical LPIs is in the IRS_IST_BASER and
IRS_IST_CFGR registers; for virtual LPIs and virtual SPIs it will be
in the L2_VMTE VM table entry.  We would like to be able to write
generic code that can manipulate any of these ISTs.  Define a struct
which captures the config information for an IST, and cache the
IRS_IST_CFGR/IRS_IST_BASER data into this format when the guest sets
the VALID bit.

This also allows us to enforce the correct handling of reserved and
out-of-range values, and expand the encodings of sizes into a more
convenient format for later use.

Signed-off-by: Peter Maydell <[email protected]>
---
 hw/intc/arm_gicv5.c         | 64 +++++++++++++++++++++++++++++++++++++
 hw/intc/trace-events        |  2 ++
 include/hw/intc/arm_gicv5.h | 12 +++++++
 3 files changed, 78 insertions(+)

diff --git a/hw/intc/arm_gicv5.c b/hw/intc/arm_gicv5.c
index f5933197ea..3f74069e01 100644
--- a/hw/intc/arm_gicv5.c
+++ b/hw/intc/arm_gicv5.c
@@ -278,9 +278,68 @@ static void irs_ist_baser_write(GICv5 *s, GICv5Domain 
domain, uint64_t value)
         }
         cs->irs_ist_baser[domain] = FIELD_DP64(cs->irs_ist_baser[domain],
                                                IRS_IST_BASER, VALID, valid);
+        s->phys_lpi_config[domain].valid = false;
+        trace_gicv5_ist_invalid(domain_name[domain]);
         return;
     }
     cs->irs_ist_baser[domain] = value;
+
+    if (FIELD_EX64(cs->irs_ist_baser[domain], IRS_IST_BASER, VALID)) {
+        /*
+         * If the guest just set VALID then capture data into config struct,
+         * sanitize the reserved values, and expand fields out into byte 
counts.
+         */
+        GICv5ISTConfig *cfg = &s->phys_lpi_config[domain];
+        uint8_t istbits, l2bits, l2_idx_bits;
+        uint8_t id_bits = FIELD_EX64(cs->irs_ist_cfgr[domain],
+                                     IRS_IST_CFGR, LPI_ID_BITS);
+        id_bits = MIN(MAX(id_bits, QEMU_GICV5_MIN_LPI_ID_BITS), 
QEMU_GICV5_ID_BITS);
+
+        switch (FIELD_EX64(cs->irs_ist_cfgr[domain], IRS_IST_CFGR, ISTSZ)) {
+        case 0:
+        case 3: /* reserved: acts like the minimum required size */
+            istbits = 2;
+            break;
+        case 1:
+            istbits = 3;
+            break;
+        case 2:
+            istbits = 4;
+            break;
+        default:
+            g_assert_not_reached();
+        }
+        switch (FIELD_EX64(cs->irs_ist_cfgr[domain], IRS_IST_CFGR, L2SZ)) {
+        case 0:
+        case 3: /* reserved; CONSTRAINED UNPREDICTABLE */
+            l2bits = 12; /* 4K: 12 bits */
+            break;
+        case 1:
+            l2bits = 14; /* 16K: 14 bits */
+            break;
+        case 2:
+            l2bits = 16; /* 64K: 16 bits */
+            break;
+        default:
+            g_assert_not_reached();
+        }
+        /*
+         * Calculate how many bits of an ID index the L2 table
+         * (e.g. if we need 14 bits to index each byte in a 16K L2 table,
+         * but each entry is 4 bytes wide then we need 14 - 2 = 12 bits
+         * to index an entry in the table).
+         */
+        l2_idx_bits = l2bits - istbits;
+        cfg->base = cs->irs_ist_baser[domain] & R_IRS_IST_BASER_ADDR_MASK;
+        cfg->id_bits = id_bits;
+        cfg->istsz = 1 << istbits;
+        cfg->l2_idx_bits = l2_idx_bits;
+        cfg->structure = FIELD_EX64(cs->irs_ist_cfgr[domain],
+                                    IRS_IST_CFGR, STRUCTURE);
+        cfg->valid = true;
+        trace_gicv5_ist_valid(domain_name[domain], cfg->base, cfg->id_bits,
+                              cfg->l2_idx_bits, cfg->istsz, cfg->structure);
+    }
 }
 
 static bool config_readl(GICv5 *s, GICv5Domain domain, hwaddr offset,
@@ -568,6 +627,11 @@ static void gicv5_reset_hold(Object *obj, ResetType type)
     if (c->parent_phases.hold) {
         c->parent_phases.hold(obj, type);
     }
+
+    /* IRS_IST_BASER and IRS_IST_CFGR reset to 0, clear cached info */
+    for (int i = 0; i < NUM_GICV5_DOMAINS; i++) {
+        s->phys_lpi_config[i].valid = false;
+    }
 }
 
 static void gicv5_set_idregs(GICv5Common *cs)
diff --git a/hw/intc/trace-events b/hw/intc/trace-events
index 0797a23c1a..80fc47794b 100644
--- a/hw/intc/trace-events
+++ b/hw/intc/trace-events
@@ -233,6 +233,8 @@ gicv5_badread(const char *domain, uint64_t offset, unsigned 
size) "GICv5 IRS %s
 gicv5_write(const char *domain, uint64_t offset, uint64_t data, unsigned size) 
"GICv5 IRS %s config frame write: offset 0x%" PRIx64 " data 0x%" PRIx64 " size 
%u"
 gicv5_badwrite(const char *domain, uint64_t offset, uint64_t data, unsigned 
size) "GICv5 IRS %s config frame write: offset 0x%" PRIx64 " data 0x%" PRIx64 " 
size %u: error"
 gicv5_spi(uint32_t id, int level) "GICv5 SPI ID %u asserted at level %d"
+gicv5_ist_valid(const char *domain, uint64_t base, uint8_t id_bits, uint8_t 
l2_idx_bits, uint8_t istsz, bool structure) "GICv5 IRS %s IST now valid: base 
0x%" PRIx64 " id_bits %u l2_idx_bits %u IST entry size %u 2-level %d"
+gicv5_ist_invalid(const char *domain) "GICv5 IRS %s IST no longer valid"
 
 # arm_gicv5_common.c
 gicv5_common_realize(uint32_t irsid, uint32_t num_cpus, uint32_t spi_base, 
uint32_t spi_irs_range, uint32_t spi_range) "GICv5 IRS realized: IRS ID %u, %u 
CPUs, SPI base %u, SPI IRS range %u, SPI range %u"
diff --git a/include/hw/intc/arm_gicv5.h b/include/hw/intc/arm_gicv5.h
index 42ccef8474..f6ecd9c323 100644
--- a/include/hw/intc/arm_gicv5.h
+++ b/include/hw/intc/arm_gicv5.h
@@ -17,11 +17,23 @@
 
 OBJECT_DECLARE_TYPE(GICv5, GICv5Class, ARM_GICV5)
 
+typedef struct GICv5ISTConfig {
+    hwaddr base; /* Base address */
+    uint8_t id_bits; /* number of bits in an ID for this table */
+    uint8_t l2_idx_bits; /* number of ID bits that index into L2 table */
+    uint8_t istsz; /* L2 ISTE size in bytes */
+    bool structure; /* true if using 2-level table */
+    bool valid; /* true if this table is valid and usable */
+} GICv5ISTConfig;
+
 /*
  * This class is for TCG-specific state for the GICv5.
  */
 struct GICv5 {
     GICv5Common parent_obj;
+
+    /* This is the info from IRS_IST_BASER and IRS_IST_CFGR */
+    GICv5ISTConfig phys_lpi_config[NUM_GICV5_DOMAINS];
 };
 
 struct GICv5Class {
-- 
2.43.0


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