[Qemu-devel] [PATCH v1 11/28] target/riscv: Add background register swapping function

[Alistair Francis <alistair.francis@wdc.com>]

Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
---
 target/riscv/cpu.h        | 24 ++++++++---
 target/riscv/cpu_bits.h   |  7 ++++
 target/riscv/cpu_helper.c | 88 +++++++++++++++++++++++++++++++++++++++
 3 files changed, 113 insertions(+), 6 deletions(-)

diff --git a/target/riscv/cpu.h b/target/riscv/cpu.h
index 680592cb60..05957f32a8 100644
--- a/target/riscv/cpu.h
+++ b/target/riscv/cpu.h
@@ -125,15 +125,18 @@ struct CPURISCVState {
     target_ulong *mstatus;
 
     /*
-     * CAUTION! Unlike the rest of this struct, mip is accessed asynchonously
-     * by I/O threads. It should be read with atomic_read. It should be updated
-     * using riscv_cpu_update_mip with the iothread mutex held. The iothread
-     * mutex must be held because mip must be consistent with the CPU inturrept
-     * state. riscv_cpu_update_mip calls cpu_interrupt or cpu_reset_interrupt
-     * wuth the invariant that CPU_INTERRUPT_HARD is set iff mip is non-zero.
+     * CAUTION! Unlike the rest of this struct, mip and mip_novirt is accessed
+     * asynchonously by I/O threads. It should be read with atomic_read. It should
+     * be updated using riscv_cpu_update_mip with the iothread mutex held. The
+     * iothread mutex must be held because mip must be consistent with the CPU
+     * inturrept state. riscv_cpu_update_mip calls cpu_interrupt or
+     * cpu_reset_interrupt wuth the invariant that CPU_INTERRUPT_HARD is set if
+     * mip is non-zero.
      * mip is 32-bits to allow atomic_read on 32-bit hosts.
      */
     uint32_t mip;
+    uint32_t mip_novirt;
+
     uint32_t miclaim;
 
     target_ulong *mie;
@@ -179,6 +182,14 @@ struct CPURISCVState {
     target_ulong vstval;
     target_ulong vsatp;
 
+    /* HS Backup CSRs */
+    target_ulong stvec_hs;
+    target_ulong sscratch_hs;
+    target_ulong sepc_hs;
+    target_ulong scause_hs;
+    target_ulong stval_hs;
+    target_ulong satp_hs;
+
     target_ulong scounteren;
     target_ulong mcounteren;
 
@@ -306,6 +317,7 @@ void riscv_cpu_list(void);
 #define cpu_mmu_index riscv_cpu_mmu_index
 
 #ifndef CONFIG_USER_ONLY
+void riscv_cpu_swap_hypervisor_regs(CPURISCVState *env);
 int riscv_cpu_claim_interrupts(RISCVCPU *cpu, uint32_t interrupts);
 uint32_t riscv_cpu_update_mip(RISCVCPU *cpu, uint32_t mask, uint32_t value);
 #define BOOL_TO_MASK(x) (-!!(x)) /* helper for riscv_cpu_update_mip value */
diff --git a/target/riscv/cpu_bits.h b/target/riscv/cpu_bits.h
index 78067901a2..5cee72b726 100644
--- a/target/riscv/cpu_bits.h
+++ b/target/riscv/cpu_bits.h
@@ -556,4 +556,11 @@
 #define SIP_STIP                           MIP_STIP
 #define SIP_SEIP                           MIP_SEIP
 
+/* MIE masks */
+#define MIE_SEIE                           (1 << IRQ_S_EXT)
+#define MIE_UEIE                           (1 << IRQ_U_EXT)
+#define MIE_STIE                           (1 << IRQ_S_TIMER)
+#define MIE_UTIE                           (1 << IRQ_U_TIMER)
+#define MIE_SSIE                           (1 << IRQ_S_SOFT)
+#define MIE_USIE                           (1 << IRQ_U_SOFT)
 #endif
diff --git a/target/riscv/cpu_helper.c b/target/riscv/cpu_helper.c
index c597523d74..41d4368128 100644
--- a/target/riscv/cpu_helper.c
+++ b/target/riscv/cpu_helper.c
@@ -81,6 +81,94 @@ bool riscv_cpu_fp_enabled(CPURISCVState *env)
     return false;
 }
 
+void riscv_cpu_swap_hypervisor_regs(CPURISCVState *env)
+{
+    RISCVCPU *cpu = RISCV_CPU(env_cpu(env));
+    uint32_t tmp;
+    target_ulong mstatus_mask = MSTATUS_MXR | MSTATUS_SUM | MSTATUS_FS |
+                                MSTATUS_SPP | MSTATUS_SPIE | MSTATUS_SIE;
+    target_ulong sie_mask = MIE_SEIE | MIE_STIE | MIE_SSIE |
+                            MIE_UEIE | MIE_UTIE | MIE_USIE;
+    target_ulong mip_mask = MIP_SSIP | MIP_STIP | MIP_SEIP;
+    bool current_virt = riscv_cpu_virt_enabled(env);
+
+    g_assert(riscv_has_ext(env, RVH));
+
+#if defined(TARGET_RISCV64)
+    mstatus_mask |= MSTATUS64_UXL;
+#endif
+
+    if (current_virt) {
+        /* Current V=1 and we are about to change to V=0 */
+        env->mstatus = &env->mstatus_novirt;
+        *env->mstatus &= mstatus_mask;
+        *env->mstatus |= env->vsstatus & ~mstatus_mask;
+        /* Ensure that vsstatus only holds the correct bits */
+        env->vsstatus &= mstatus_mask;
+
+        env->mie = &env->mie_novirt;
+        *env->mie &= sie_mask;
+        *env->mie |= env->vsie & ~sie_mask;
+        /* Ensure that vsie only holds the correct bits */
+        env->vsie &= sie_mask;
+
+        env->vstvec = env->stvec;
+        env->stvec = env->stvec_hs;
+
+        env->vsscratch = env->sscratch;
+        env->sscratch = env->sscratch_hs;
+
+        env->vsepc = env->sepc;
+        env->sepc = env->sepc_hs;
+
+        env->vscause = env->scause;
+        env->scause = env->scause_hs;
+
+        env->vstval = env->sbadaddr;
+        env->sbadaddr = env->stval_hs;
+
+        env->vsatp = env->satp;
+        env->satp = env->satp_hs;
+
+        tmp = (uint32_t)atomic_read(&env->mip_novirt);
+        tmp = riscv_cpu_update_mip(cpu, mip_mask, tmp);
+        tmp &= mip_mask;
+        atomic_set(&env->vsip, tmp);
+    } else {
+        /* Current V=0 and we are about to change to V=1 */
+        env->mstatus = &env->vsstatus;
+        *env->mstatus &= mstatus_mask;
+        *env->mstatus |= env->mstatus_novirt & ~mstatus_mask;
+
+        env->mie = &env->vsie;
+        *env->mie &= sie_mask;
+        *env->mie |= env->mie_novirt & ~sie_mask;
+
+        env->stvec_hs = env->stvec;
+        env->stvec = env->vstvec;
+
+        env->sscratch_hs = env->sscratch;
+        env->sscratch = env->vsscratch;
+
+        env->sepc_hs = env->sepc;
+        env->sepc = env->vsepc;
+
+        env->scause_hs = env->scause;
+        env->scause = env->vscause;
+
+        env->stval_hs = env->sbadaddr;
+        env->sbadaddr = env->vstval;
+
+        env->satp_hs = env->satp;
+        env->satp = env->vsatp;
+
+        tmp = (uint32_t)atomic_read(&env->vsip);
+        tmp = riscv_cpu_update_mip(cpu, mip_mask, tmp);
+        tmp &= mip_mask;
+        atomic_set(&env->mip_novirt, tmp);
+    }
+}
+
 bool riscv_cpu_virt_enabled(CPURISCVState *env)
 {
     bool tmp;
-- 
2.22.0