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Add Svukte extension support #2121

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2 changes: 2 additions & 0 deletions disasm/isa_parser.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -265,6 +265,8 @@ isa_parser_t::isa_parser_t(const char* str, const char *priv)
extension_table[EXT_SVPBMT] = true;
} else if (ext_str == "svinval") {
extension_table[EXT_SVINVAL] = true;
} else if (ext_str == "svukte") {
extension_table[EXT_SVUKTE] = true;
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@aswaterman aswaterman Nov 5, 2025

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We should have a check that XLEN is 64 and issue an error if not.

} else if (ext_str == "zfa") {
extension_table[EXT_ZFA] = true;
} else if (ext_str == "zicbom") {
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1 change: 1 addition & 0 deletions riscv/csr_init.cc
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Expand Up @@ -329,6 +329,7 @@ void state_t::csr_init(processor_t* const proc, reg_t max_isa)
}
const reg_t senvcfg_mask = (proc->extension_enabled(EXT_ZICBOM) ? SENVCFG_CBCFE | SENVCFG_CBIE : 0) |
(proc->extension_enabled(EXT_ZICBOZ) ? SENVCFG_CBZE : 0) |
(proc->extension_enabled(EXT_SVUKTE) ? SENVCFG_UKTE : 0) |
(proc->extension_enabled(EXT_SSNPM) ? SENVCFG_PMM : 0) |
(proc->extension_enabled(EXT_ZICFILP) ? SENVCFG_LPE : 0) |
(proc->extension_enabled(EXT_ZICFISS) ? SENVCFG_SSE : 0);
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3 changes: 2 additions & 1 deletion riscv/csrs.cc
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Expand Up @@ -2020,7 +2020,8 @@ hstatus_csr_t::hstatus_csr_t(processor_t* const proc, const reg_t addr):
}

bool hstatus_csr_t::unlogged_write(const reg_t val) noexcept {
const reg_t mask = HSTATUS_VTSR | HSTATUS_VTW
const reg_t mask = (proc->extension_enabled(EXT_SVUKTE) ? HSTATUS_HUKTE : 0)
| HSTATUS_VTSR | HSTATUS_VTW
| (proc->supports_impl(IMPL_MMU) ? HSTATUS_VTVM : 0)
| (proc->extension_enabled(EXT_SSNPM) ? HSTATUS_HUPMM : 0)
| HSTATUS_HU | HSTATUS_SPVP | HSTATUS_SPV | HSTATUS_GVA;
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1 change: 1 addition & 0 deletions riscv/isa_parser.h
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Expand Up @@ -47,6 +47,7 @@ typedef enum {
EXT_SVNAPOT,
EXT_SVPBMT,
EXT_SVINVAL,
EXT_SVUKTE,
EXT_ZDINX,
EXT_ZFA,
EXT_ZFBFMIN,
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44 changes: 38 additions & 6 deletions riscv/mmu.cc
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Expand Up @@ -53,6 +53,16 @@ void throw_access_exception(bool virt, reg_t addr, access_type type)
}
}

[[noreturn]] void throw_page_access_exception(bool virt, reg_t addr, access_type type)
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@aswaterman aswaterman Nov 5, 2025

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Rename this function to throw_page_fault_exception.

{
switch (type) {
case FETCH: throw trap_instruction_page_fault(virt, addr, 0, 0);
case LOAD: throw trap_load_page_fault(virt, addr, 0, 0);
case STORE: throw trap_store_page_fault(virt, addr, 0, 0);
default: abort();
}
}

reg_t mmu_t::translate(mem_access_info_t access_info, reg_t len)
{
reg_t addr = access_info.transformed_vaddr;
Expand Down Expand Up @@ -560,6 +570,29 @@ reg_t mmu_t::s2xlate(reg_t gva, reg_t gpa, access_type type, access_type trap_ty
}
}

bool mmu_t::check_svukte_qualified(reg_t addr, reg_t mode, bool forced_virt)
{
state_t* state = proc->get_state();

if (mode != PRV_U)
return true;

if (proc->extension_enabled('S') && get_field(state->senvcfg->read(), SENVCFG_UKTE)) {
if (forced_virt && state->prv == PRV_U) {
bool hstatus_hukte = proc->extension_enabled('H') && (get_field(state->hstatus->read(), HSTATUS_HUKTE) == 1);
return !hstatus_hukte;
}

if (((addr >> SYS_MEM_HEADING_BIT) & 0x1)) {
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@aswaterman aswaterman Nov 5, 2025 •
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I think we should have assert(proc->get_xlen() == 64) here. Then we can simply write if ((addr >> 63) & 1).

return ((state->v || forced_virt) &&
((proc->get_xlen() == 64) ? ((state->vsatp->read() & SATP64_MODE) == 0) :
((state->vsatp->read() & SATP32_MODE) == 0)));
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@aswaterman aswaterman Nov 5, 2025

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And then we can get rid of the XLEN=32 stuff here.

}
}

return true;
}

reg_t mmu_t::walk(mem_access_info_t access_info)
{
access_type type = access_info.type;
Expand All @@ -582,6 +615,10 @@ reg_t mmu_t::walk(mem_access_info_t access_info)
if (vm.levels == 0)
return s2xlate(addr, addr & ((reg_t(2) << (proc->xlen-1))-1), type, type, virt, hlvx, false) & ~page_mask; // zero-extend from xlen

if (proc->extension_enabled(EXT_SVUKTE) && !check_svukte_qualified(addr, mode, access_info.flags.forced_virt)) {
throw_page_access_exception(virt, addr, type);
}

bool s_mode = mode == PRV_S;
bool sum = proc->state.sstatus->readvirt(virt) & MSTATUS_SUM;
bool mxr = (proc->state.sstatus->readvirt(false) | proc->state.sstatus->readvirt(virt)) & MSTATUS_MXR;
Expand Down Expand Up @@ -672,12 +709,7 @@ reg_t mmu_t::walk(mem_access_info_t access_info)
}
}

switch (type) {
case FETCH: throw trap_instruction_page_fault(virt, addr, 0, 0);
case LOAD: throw trap_load_page_fault(virt, addr, 0, 0);
case STORE: throw trap_store_page_fault(virt, addr, 0, 0);
default: abort();
}
throw_page_access_exception(virt, addr, type);
}

void mmu_t::register_memtracer(memtracer_t* t)
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5 changes: 5 additions & 0 deletions riscv/mmu.h
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Expand Up @@ -34,6 +34,9 @@ const reg_t PGSIZE = 1 << PGSHIFT;
#define MMU_OBSERVE_STORE(addr, data, length)
#endif

// Svukte extension
#define SYS_MEM_HEADING_BIT 63
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@aswaterman aswaterman Nov 5, 2025

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And we can get rid of this, too.


struct insn_fetch_t
{
insn_func_t func;
Expand Down Expand Up @@ -78,6 +81,7 @@ struct mem_access_info_t {
};

void throw_access_exception(bool virt, reg_t addr, access_type type);
[[noreturn]] void throw_page_access_exception(bool virt, reg_t addr, access_type type);

// this class implements a processor's port into the virtual memory system.
// an MMU and instruction cache are maintained for simulator performance.
Expand Down Expand Up @@ -447,6 +451,7 @@ class mmu_t
check_triggers(operation, address, virt, address, data);
}
void check_triggers(triggers::operation_t operation, reg_t address, bool virt, reg_t tval, std::optional<reg_t> data);
bool check_svukte_qualified(reg_t addr, reg_t mode, bool forced_virt);
reg_t translate(mem_access_info_t access_info, reg_t len);

reg_t pte_load(reg_t pte_paddr, reg_t addr, bool virt, access_type trap_type, size_t ptesize) {
Expand Down
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