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target/i386: Use atomic operations for pte updates 

Use probe_access_full in order to resolve to a host address,
which then lets us use a host cmpxchg to update the pte.

Resolves: https://gitlab.com/qemu-project/qemu/-/issues/279
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20221002172956.265735-9-richard.henderson@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Richard Henderson 2022-10-02 10:29:55 -07:00 committed by Paolo Bonzini
parent 11b4e971dc
commit 4a1e9d4d11
1 changed files with 168 additions and 74 deletions
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242
target/i386/tcg/sysemu/excp_helper.c
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@ -27,8 +27,8 @@ typedef struct TranslateParams {
target_ulong cr3;
int pg_mode;
int mmu_idx;
int ptw_idx;
MMUAccessType access_type;
bool use_stage2;
} TranslateParams;
typedef struct TranslateResult {
@ -50,43 +50,106 @@ typedef struct TranslateFault {
TranslateFaultStage2 stage2;
} TranslateFault;
#define PTE_HPHYS(ADDR) \
do { \
if (in->use_stage2) { \
nested_in.addr = (ADDR); \
if (!mmu_translate(env, &nested_in, out, err)) { \
err->stage2 = S2_GPT; \
return false; \
} \
(ADDR) = out->paddr; \
} \
} while (0)
typedef struct PTETranslate {
CPUX86State *env;
TranslateFault *err;
int ptw_idx;
void *haddr;
hwaddr gaddr;
} PTETranslate;
static bool ptw_translate(PTETranslate *inout, hwaddr addr)
{
CPUTLBEntryFull *full;
int flags;
inout->gaddr = addr;
flags = probe_access_full(inout->env, addr, MMU_DATA_STORE,
inout->ptw_idx, true, &inout->haddr, &full, 0);
if (unlikely(flags & TLB_INVALID_MASK)) {
TranslateFault *err = inout->err;
assert(inout->ptw_idx == MMU_NESTED_IDX);
err->exception_index = 0; /* unused */
err->error_code = inout->env->error_code;
err->cr2 = addr;
err->stage2 = S2_GPT;
return false;
}
return true;
}
static inline uint32_t ptw_ldl(const PTETranslate *in)
{
if (likely(in->haddr)) {
return ldl_p(in->haddr);
}
return cpu_ldl_mmuidx_ra(in->env, in->gaddr, in->ptw_idx, 0);
}
static inline uint64_t ptw_ldq(const PTETranslate *in)
{
if (likely(in->haddr)) {
return ldq_p(in->haddr);
}
return cpu_ldq_mmuidx_ra(in->env, in->gaddr, in->ptw_idx, 0);
}
/*
* Note that we can use a 32-bit cmpxchg for all page table entries,
* even 64-bit ones, because PG_PRESENT_MASK, PG_ACCESSED_MASK and
* PG_DIRTY_MASK are all in the low 32 bits.
*/
static bool ptw_setl_slow(const PTETranslate *in, uint32_t old, uint32_t new)
{
uint32_t cmp;
/* Does x86 really perform a rmw cycle on mmio for ptw? */
start_exclusive();
cmp = cpu_ldl_mmuidx_ra(in->env, in->gaddr, in->ptw_idx, 0);
if (cmp == old) {
cpu_stl_mmuidx_ra(in->env, in->gaddr, new, in->ptw_idx, 0);
}
end_exclusive();
return cmp == old;
}
static inline bool ptw_setl(const PTETranslate *in, uint32_t old, uint32_t set)
{
if (set & ~old) {
uint32_t new = old | set;
if (likely(in->haddr)) {
old = cpu_to_le32(old);
new = cpu_to_le32(new);
return qatomic_cmpxchg((uint32_t *)in->haddr, old, new) == old;
}
return ptw_setl_slow(in, old, new);
}
return true;
}
static bool mmu_translate(CPUX86State *env, const TranslateParams *in,
TranslateResult *out, TranslateFault *err)
{
TranslateParams nested_in = {
/* Use store for page table entries, to allow A/D flag updates. */
.access_type = MMU_DATA_STORE,
.cr3 = env->nested_cr3,
.pg_mode = env->nested_pg_mode,
.mmu_idx = MMU_USER_IDX,
.use_stage2 = false,
};
CPUState *cs = env_cpu(env);
X86CPU *cpu = env_archcpu(env);
const int32_t a20_mask = x86_get_a20_mask(env);
const target_ulong addr = in->addr;
const int pg_mode = in->pg_mode;
const bool is_user = (in->mmu_idx == MMU_USER_IDX);
const MMUAccessType access_type = in->access_type;
uint64_t ptep, pte;
uint64_t ptep, pte, rsvd_mask;
PTETranslate pte_trans = {
.env = env,
.err = err,
.ptw_idx = in->ptw_idx,
};
hwaddr pte_addr;
uint64_t rsvd_mask = PG_ADDRESS_MASK & ~MAKE_64BIT_MASK(0, cpu->phys_bits);
uint32_t pkr;
int page_size;
restart_all:
rsvd_mask = ~MAKE_64BIT_MASK(0, env_archcpu(env)->phys_bits);
rsvd_mask &= PG_ADDRESS_MASK;
if (!(pg_mode & PG_MODE_NXE)) {
rsvd_mask |= PG_NX_MASK;
}
@ -100,17 +163,19 @@ static bool mmu_translate(CPUX86State *env, const TranslateParams *in,
*/
pte_addr = ((in->cr3 & ~0xfff) +
(((addr >> 48) & 0x1ff) << 3)) & a20_mask;
PTE_HPHYS(pte_addr);
pte = x86_ldq_phys(cs, pte_addr);
if (!ptw_translate(&pte_trans, pte_addr)) {
return false;
}
restart_5:
pte = ptw_ldq(&pte_trans);
if (!(pte & PG_PRESENT_MASK)) {
goto do_fault;
}
if (pte & (rsvd_mask | PG_PSE_MASK)) {
goto do_fault_rsvd;
}
if (!(pte & PG_ACCESSED_MASK)) {
pte |= PG_ACCESSED_MASK;
x86_stl_phys_notdirty(cs, pte_addr, pte);
if (!ptw_setl(&pte_trans, pte, PG_ACCESSED_MASK)) {
goto restart_5;
}
ptep = pte ^ PG_NX_MASK;
} else {
@ -123,17 +188,19 @@ static bool mmu_translate(CPUX86State *env, const TranslateParams *in,
*/
pte_addr = ((pte & PG_ADDRESS_MASK) +
(((addr >> 39) & 0x1ff) << 3)) & a20_mask;
PTE_HPHYS(pte_addr);
pte = x86_ldq_phys(cs, pte_addr);
if (!ptw_translate(&pte_trans, pte_addr)) {
return false;
}
restart_4:
pte = ptw_ldq(&pte_trans);
if (!(pte & PG_PRESENT_MASK)) {
goto do_fault;
}
if (pte & (rsvd_mask | PG_PSE_MASK)) {
goto do_fault_rsvd;
}
if (!(pte & PG_ACCESSED_MASK)) {
pte |= PG_ACCESSED_MASK;
x86_stl_phys_notdirty(cs, pte_addr, pte);
if (!ptw_setl(&pte_trans, pte, PG_ACCESSED_MASK)) {
goto restart_4;
}
ptep &= pte ^ PG_NX_MASK;
@ -142,19 +209,21 @@ static bool mmu_translate(CPUX86State *env, const TranslateParams *in,
*/
pte_addr = ((pte & PG_ADDRESS_MASK) +
(((addr >> 30) & 0x1ff) << 3)) & a20_mask;
PTE_HPHYS(pte_addr);
pte = x86_ldq_phys(cs, pte_addr);
if (!ptw_translate(&pte_trans, pte_addr)) {
return false;
}
restart_3_lma:
pte = ptw_ldq(&pte_trans);
if (!(pte & PG_PRESENT_MASK)) {
goto do_fault;
}
if (pte & rsvd_mask) {
goto do_fault_rsvd;
}
ptep &= pte ^ PG_NX_MASK;
if (!(pte & PG_ACCESSED_MASK)) {
pte |= PG_ACCESSED_MASK;
x86_stl_phys_notdirty(cs, pte_addr, pte);
if (!ptw_setl(&pte_trans, pte, PG_ACCESSED_MASK)) {
goto restart_3_lma;
}
ptep &= pte ^ PG_NX_MASK;
if (pte & PG_PSE_MASK) {
/* 1 GB page */
page_size = 1024 * 1024 * 1024;
@ -167,15 +236,21 @@ static bool mmu_translate(CPUX86State *env, const TranslateParams *in,
* Page table level 3
*/
pte_addr = ((in->cr3 & ~0x1f) + ((addr >> 27) & 0x18)) & a20_mask;
PTE_HPHYS(pte_addr);
pte = x86_ldq_phys(cs, pte_addr);
if (!ptw_translate(&pte_trans, pte_addr)) {
return false;
}
rsvd_mask |= PG_HI_USER_MASK;
restart_3_nolma:
pte = ptw_ldq(&pte_trans);
if (!(pte & PG_PRESENT_MASK)) {
goto do_fault;
}
rsvd_mask |= PG_HI_USER_MASK;
if (pte & (rsvd_mask | PG_NX_MASK)) {
goto do_fault_rsvd;
}
if (!ptw_setl(&pte_trans, pte, PG_ACCESSED_MASK)) {
goto restart_3_nolma;
}
ptep = PG_NX_MASK | PG_USER_MASK | PG_RW_MASK;
}
@ -184,32 +259,37 @@ static bool mmu_translate(CPUX86State *env, const TranslateParams *in,
*/
pte_addr = ((pte & PG_ADDRESS_MASK) +
(((addr >> 21) & 0x1ff) << 3)) & a20_mask;
PTE_HPHYS(pte_addr);
pte = x86_ldq_phys(cs, pte_addr);
if (!ptw_translate(&pte_trans, pte_addr)) {
return false;
}
restart_2_pae:
pte = ptw_ldq(&pte_trans);
if (!(pte & PG_PRESENT_MASK)) {
goto do_fault;
}
if (pte & rsvd_mask) {
goto do_fault_rsvd;
}
ptep &= pte ^ PG_NX_MASK;
if (pte & PG_PSE_MASK) {
/* 2 MB page */
page_size = 2048 * 1024;
ptep &= pte ^ PG_NX_MASK;
goto do_check_protect;
}
if (!(pte & PG_ACCESSED_MASK)) {
pte |= PG_ACCESSED_MASK;
x86_stl_phys_notdirty(cs, pte_addr, pte);
if (!ptw_setl(&pte_trans, pte, PG_ACCESSED_MASK)) {
goto restart_2_pae;
}
ptep &= pte ^ PG_NX_MASK;
/*
* Page table level 1
*/
pte_addr = ((pte & PG_ADDRESS_MASK) +
(((addr >> 12) & 0x1ff) << 3)) & a20_mask;
PTE_HPHYS(pte_addr);
pte = x86_ldq_phys(cs, pte_addr);
if (!ptw_translate(&pte_trans, pte_addr)) {
return false;
}
pte = ptw_ldq(&pte_trans);
if (!(pte & PG_PRESENT_MASK)) {
goto do_fault;
}
@ -224,8 +304,11 @@ static bool mmu_translate(CPUX86State *env, const TranslateParams *in,
* Page table level 2
*/
pte_addr = ((in->cr3 & ~0xfff) + ((addr >> 20) & 0xffc)) & a20_mask;
PTE_HPHYS(pte_addr);
pte = x86_ldl_phys(cs, pte_addr);
if (!ptw_translate(&pte_trans, pte_addr)) {
return false;
}
restart_2_nopae:
pte = ptw_ldl(&pte_trans);
if (!(pte & PG_PRESENT_MASK)) {
goto do_fault;
}
@ -242,17 +325,18 @@ static bool mmu_translate(CPUX86State *env, const TranslateParams *in,
rsvd_mask = 0x200000;
goto do_check_protect_pse36;
}
if (!(pte & PG_ACCESSED_MASK)) {
pte |= PG_ACCESSED_MASK;
x86_stl_phys_notdirty(cs, pte_addr, pte);
if (!ptw_setl(&pte_trans, pte, PG_ACCESSED_MASK)) {
goto restart_2_nopae;
}
/*
* Page table level 1
*/
pte_addr = ((pte & ~0xfffu) + ((addr >> 10) & 0xffc)) & a20_mask;
PTE_HPHYS(pte_addr);
pte = x86_ldl_phys(cs, pte_addr);
if (!ptw_translate(&pte_trans, pte_addr)) {
return false;
}
pte = ptw_ldl(&pte_trans);
if (!(pte & PG_PRESENT_MASK)) {
goto do_fault;
}
@ -319,27 +403,35 @@ do_check_protect_pse36:
uint32_t set = PG_ACCESSED_MASK;
if (access_type == MMU_DATA_STORE) {
set |= PG_DIRTY_MASK;
} else if (!(pte & PG_DIRTY_MASK)) {
/*
* Only set write access if already dirty...
* otherwise wait for dirty access.
*/
prot &= ~PAGE_WRITE;
}
if (set & ~pte) {
pte |= set;
x86_stl_phys_notdirty(cs, pte_addr, pte);
if (!ptw_setl(&pte_trans, pte, set)) {
/*
* We can arrive here from any of 3 levels and 2 formats.
* The only safe thing is to restart the entire lookup.
*/
goto restart_all;
}
}
if (!(pte & PG_DIRTY_MASK)) {
/* only set write access if already dirty... otherwise wait
for dirty access */
assert(access_type != MMU_DATA_STORE);
prot &= ~PAGE_WRITE;
}
/* align to page_size */
out->paddr = (pte & a20_mask & PG_ADDRESS_MASK & ~(page_size - 1))
| (addr & (page_size - 1));
if (in->use_stage2) {
nested_in.addr = out->paddr;
nested_in.access_type = access_type;
if (in->ptw_idx == MMU_NESTED_IDX) {
TranslateParams nested_in = {
.addr = out->paddr,
.access_type = access_type,
.cr3 = env->nested_cr3,
.pg_mode = env->nested_pg_mode,
.mmu_idx = MMU_USER_IDX,
.ptw_idx = MMU_PHYS_IDX,
};
if (!mmu_translate(env, &nested_in, out, err)) {
err->stage2 = S2_GPA;
@ -436,7 +528,7 @@ static bool get_physical_address(CPUX86State *env, vaddr addr,
in.cr3 = env->nested_cr3;
in.pg_mode = env->nested_pg_mode;
in.mmu_idx = MMU_USER_IDX;
in.use_stage2 = false;
in.ptw_idx = MMU_PHYS_IDX;
if (!mmu_translate(env, &in, out, err)) {
err->stage2 = S2_GPA;
@ -449,7 +541,7 @@ static bool get_physical_address(CPUX86State *env, vaddr addr,
default:
in.cr3 = env->cr[3];
in.mmu_idx = mmu_idx;
in.use_stage2 = use_stage2;
in.ptw_idx = use_stage2 ? MMU_NESTED_IDX : MMU_PHYS_IDX;
in.pg_mode = get_pg_mode(env);
if (likely(in.pg_mode)) {
@ -504,6 +596,8 @@ bool x86_cpu_tlb_fill(CPUState *cs, vaddr addr, int size,
}
if (probe) {
/* This will be used if recursing for stage2 translation. */
env->error_code = err.error_code;
return false;
}