target-i386: Add NPT support

This implements NPT suport for SVM by hooking into
x86_cpu_handle_mmu_fault where it reads the stage-1 page table. Whether
we need to perform this 2nd stage translation, and how, is decided
during vmrun and stored in hflags2, along with nested_cr3 and
nested_pg_mode.

As get_hphys performs a direct cpu_vmexit in case of NPT faults, we need
retaddr in that function. To avoid changing the signature of
cpu_handle_mmu_fault, this passes the value from tlb_fill to get_hphys
via the CPU state.

This was tested successfully via the Jailhouse hypervisor.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Message-Id: <567473a0-6005-5843-4c73-951f476085ca@web.de>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

7 files changed, 281 insertions, 6 deletions

diff --git a/target/i386/cpu.c b/target/i386/cpu.c
index bdbd446..b0b87c3 100644
--- a/target/i386/cpu.c
+++ b/target/i386/cpu.c
@@ -749,7 +749,7 @@ static void x86_cpu_vendor_words2str(char *dst, uint32_t vendor1,
 #define TCG_EXT3_FEATURES (CPUID_EXT3_LAHF_LM | CPUID_EXT3_SVM | \
           CPUID_EXT3_CR8LEG | CPUID_EXT3_ABM | CPUID_EXT3_SSE4A)
 #define TCG_EXT4_FEATURES 0
-#define TCG_SVM_FEATURES 0
+#define TCG_SVM_FEATURES CPUID_SVM_NPT
 #define TCG_KVM_FEATURES 0
 #define TCG_7_0_EBX_FEATURES (CPUID_7_0_EBX_SMEP | CPUID_7_0_EBX_SMAP | \
           CPUID_7_0_EBX_BMI1 | CPUID_7_0_EBX_BMI2 | CPUID_7_0_EBX_ADX | \
diff --git a/target/i386/cpu.h b/target/i386/cpu.h
index 8b1ddfe..2c5a0d9 100644
--- a/target/i386/cpu.h
+++ b/target/i386/cpu.h
@@ -211,6 +211,7 @@ typedef enum X86Seg {
 #define HF2_VINTR_SHIFT          3 /* value of V_INTR_MASKING bit */
 #define HF2_SMM_INSIDE_NMI_SHIFT 4 /* CPU serving SMI nested inside NMI */
 #define HF2_MPX_PR_SHIFT         5 /* BNDCFGx.BNDPRESERVE */
+#define HF2_NPT_SHIFT            6 /* Nested Paging enabled */
 
 #define HF2_GIF_MASK            (1 << HF2_GIF_SHIFT)
 #define HF2_HIF_MASK            (1 << HF2_HIF_SHIFT)
@@ -218,6 +219,7 @@ typedef enum X86Seg {
 #define HF2_VINTR_MASK          (1 << HF2_VINTR_SHIFT)
 #define HF2_SMM_INSIDE_NMI_MASK (1 << HF2_SMM_INSIDE_NMI_SHIFT)
 #define HF2_MPX_PR_MASK         (1 << HF2_MPX_PR_SHIFT)
+#define HF2_NPT_MASK            (1 << HF2_NPT_SHIFT)
 
 #define CR0_PE_SHIFT 0
 #define CR0_MP_SHIFT 1
@@ -1265,12 +1267,16 @@ typedef struct CPUX86State {
     uint16_t intercept_dr_read;
     uint16_t intercept_dr_write;
     uint32_t intercept_exceptions;
+    uint64_t nested_cr3;
+    uint32_t nested_pg_mode;
     uint8_t v_tpr;
 
     /* KVM states, automatically cleared on reset */
     uint8_t nmi_injected;
     uint8_t nmi_pending;
 
+    uintptr_t retaddr;
+
     /* Fields up to this point are cleared by a CPU reset */
     struct {} end_reset_fields;
 
diff --git a/target/i386/excp_helper.c b/target/i386/excp_helper.c
index cb4d1b7..37a33d5 100644
--- a/target/i386/excp_helper.c
+++ b/target/i386/excp_helper.c
@@ -157,6 +157,209 @@ int x86_cpu_handle_mmu_fault(CPUState *cs, vaddr addr, int size,
 
 #else
 
+static hwaddr get_hphys(CPUState *cs, hwaddr gphys, MMUAccessType access_type,
+                        int *prot)
+{
+    CPUX86State *env = &X86_CPU(cs)->env;
+    uint64_t rsvd_mask = PG_HI_RSVD_MASK;
+    uint64_t ptep, pte;
+    uint64_t exit_info_1 = 0;
+    target_ulong pde_addr, pte_addr;
+    uint32_t page_offset;
+    int page_size;
+
+    if (likely(!(env->hflags2 & HF2_NPT_MASK))) {
+        return gphys;
+    }
+
+    if (!(env->nested_pg_mode & SVM_NPT_NXE)) {
+        rsvd_mask |= PG_NX_MASK;
+    }
+
+    if (env->nested_pg_mode & SVM_NPT_PAE) {
+        uint64_t pde, pdpe;
+        target_ulong pdpe_addr;
+
+#ifdef TARGET_X86_64
+        if (env->nested_pg_mode & SVM_NPT_LMA) {
+            uint64_t pml5e;
+            uint64_t pml4e_addr, pml4e;
+
+            pml5e = env->nested_cr3;
+            ptep = PG_NX_MASK | PG_USER_MASK | PG_RW_MASK;
+
+            pml4e_addr = (pml5e & PG_ADDRESS_MASK) +
+                    (((gphys >> 39) & 0x1ff) << 3);
+            pml4e = x86_ldq_phys(cs, pml4e_addr);
+            if (!(pml4e & PG_PRESENT_MASK)) {
+                goto do_fault;
+            }
+            if (pml4e & (rsvd_mask | PG_PSE_MASK)) {
+                goto do_fault_rsvd;
+            }
+            if (!(pml4e & PG_ACCESSED_MASK)) {
+                pml4e |= PG_ACCESSED_MASK;
+                x86_stl_phys_notdirty(cs, pml4e_addr, pml4e);
+            }
+            ptep &= pml4e ^ PG_NX_MASK;
+            pdpe_addr = (pml4e & PG_ADDRESS_MASK) +
+                    (((gphys >> 30) & 0x1ff) << 3);
+            pdpe = x86_ldq_phys(cs, pdpe_addr);
+            if (!(pdpe & PG_PRESENT_MASK)) {
+                goto do_fault;
+            }
+            if (pdpe & rsvd_mask) {
+                goto do_fault_rsvd;
+            }
+            ptep &= pdpe ^ PG_NX_MASK;
+            if (!(pdpe & PG_ACCESSED_MASK)) {
+                pdpe |= PG_ACCESSED_MASK;
+                x86_stl_phys_notdirty(cs, pdpe_addr, pdpe);
+            }
+            if (pdpe & PG_PSE_MASK) {
+                /* 1 GB page */
+                page_size = 1024 * 1024 * 1024;
+                pte_addr = pdpe_addr;
+                pte = pdpe;
+                goto do_check_protect;
+            }
+        } else
+#endif
+        {
+            pdpe_addr = (env->nested_cr3 & ~0x1f) + ((gphys >> 27) & 0x18);
+            pdpe = x86_ldq_phys(cs, pdpe_addr);
+            if (!(pdpe & PG_PRESENT_MASK)) {
+                goto do_fault;
+            }
+            rsvd_mask |= PG_HI_USER_MASK;
+            if (pdpe & (rsvd_mask | PG_NX_MASK)) {
+                goto do_fault_rsvd;
+            }
+            ptep = PG_NX_MASK | PG_USER_MASK | PG_RW_MASK;
+        }
+
+        pde_addr = (pdpe & PG_ADDRESS_MASK) + (((gphys >> 21) & 0x1ff) << 3);
+        pde = x86_ldq_phys(cs, pde_addr);
+        if (!(pde & PG_PRESENT_MASK)) {
+            goto do_fault;
+        }
+        if (pde & rsvd_mask) {
+            goto do_fault_rsvd;
+        }
+        ptep &= pde ^ PG_NX_MASK;
+        if (pde & PG_PSE_MASK) {
+            /* 2 MB page */
+            page_size = 2048 * 1024;
+            pte_addr = pde_addr;
+            pte = pde;
+            goto do_check_protect;
+        }
+        /* 4 KB page */
+        if (!(pde & PG_ACCESSED_MASK)) {
+            pde |= PG_ACCESSED_MASK;
+            x86_stl_phys_notdirty(cs, pde_addr, pde);
+        }
+        pte_addr = (pde & PG_ADDRESS_MASK) + (((gphys >> 12) & 0x1ff) << 3);
+        pte = x86_ldq_phys(cs, pte_addr);
+        if (!(pte & PG_PRESENT_MASK)) {
+            goto do_fault;
+        }
+        if (pte & rsvd_mask) {
+            goto do_fault_rsvd;
+        }
+        /* combine pde and pte nx, user and rw protections */
+        ptep &= pte ^ PG_NX_MASK;
+        page_size = 4096;
+    } else {
+        uint32_t pde;
+
+        /* page directory entry */
+        pde_addr = (env->nested_cr3 & ~0xfff) + ((gphys >> 20) & 0xffc);
+        pde = x86_ldl_phys(cs, pde_addr);
+        if (!(pde & PG_PRESENT_MASK)) {
+            goto do_fault;
+        }
+        ptep = pde | PG_NX_MASK;
+
+        /* if PSE bit is set, then we use a 4MB page */
+        if ((pde & PG_PSE_MASK) && (env->cr[4] & CR4_PSE_MASK)) {
+            page_size = 4096 * 1024;
+            pte_addr = pde_addr;
+
+            /* Bits 20-13 provide bits 39-32 of the address, bit 21 is reserved.
+             * Leave bits 20-13 in place for setting accessed/dirty bits below.
+             */
+            pte = pde | ((pde & 0x1fe000LL) << (32 - 13));
+            rsvd_mask = 0x200000;
+            goto do_check_protect_pse36;
+        }
+
+        if (!(pde & PG_ACCESSED_MASK)) {
+            pde |= PG_ACCESSED_MASK;
+            x86_stl_phys_notdirty(cs, pde_addr, pde);
+        }
+
+        /* page directory entry */
+        pte_addr = (pde & ~0xfff) + ((gphys >> 10) & 0xffc);
+        pte = x86_ldl_phys(cs, pte_addr);
+        if (!(pte & PG_PRESENT_MASK)) {
+            goto do_fault;
+        }
+        /* combine pde and pte user and rw protections */
+        ptep &= pte | PG_NX_MASK;
+        page_size = 4096;
+        rsvd_mask = 0;
+    }
+
+ do_check_protect:
+    rsvd_mask |= (page_size - 1) & PG_ADDRESS_MASK & ~PG_PSE_PAT_MASK;
+ do_check_protect_pse36:
+    if (pte & rsvd_mask) {
+        goto do_fault_rsvd;
+    }
+    ptep ^= PG_NX_MASK;
+
+    if (!(ptep & PG_USER_MASK)) {
+        goto do_fault_protect;
+    }
+    if (ptep & PG_NX_MASK) {
+        if (access_type == MMU_INST_FETCH) {
+            goto do_fault_protect;
+        }
+        *prot &= ~PAGE_EXEC;
+    }
+    if (!(ptep & PG_RW_MASK)) {
+        if (access_type == MMU_DATA_STORE) {
+            goto do_fault_protect;
+        }
+        *prot &= ~PAGE_WRITE;
+    }
+
+    pte &= PG_ADDRESS_MASK & ~(page_size - 1);
+    page_offset = gphys & (page_size - 1);
+    return pte + page_offset;
+
+ do_fault_rsvd:
+    exit_info_1 |= SVM_NPTEXIT_RSVD;
+ do_fault_protect:
+    exit_info_1 |= SVM_NPTEXIT_P;
+ do_fault:
+    x86_stq_phys(cs, env->vm_vmcb + offsetof(struct vmcb, control.exit_info_2),
+                 gphys);
+    exit_info_1 |= SVM_NPTEXIT_US;
+    if (access_type == MMU_DATA_STORE) {
+        exit_info_1 |= SVM_NPTEXIT_RW;
+    } else if (access_type == MMU_INST_FETCH) {
+        exit_info_1 |= SVM_NPTEXIT_ID;
+    }
+    if (prot) {
+        exit_info_1 |= SVM_NPTEXIT_GPA;
+    } else { /* page table access */
+        exit_info_1 |= SVM_NPTEXIT_GPT;
+    }
+    cpu_vmexit(env, SVM_EXIT_NPF, exit_info_1, env->retaddr);
+}
+
 /* return value:
  * -1 = cannot handle fault
  * 0  = nothing more to do
@@ -224,6 +427,7 @@ int x86_cpu_handle_mmu_fault(CPUState *cs, vaddr addr, int size,
             if (la57) {
                 pml5e_addr = ((env->cr[3] & ~0xfff) +
                         (((addr >> 48) & 0x1ff) << 3)) & a20_mask;
+                pml5e_addr = get_hphys(cs, pml5e_addr, MMU_DATA_STORE, NULL);
                 pml5e = x86_ldq_phys(cs, pml5e_addr);
                 if (!(pml5e & PG_PRESENT_MASK)) {
                     goto do_fault;
@@ -243,6 +447,7 @@ int x86_cpu_handle_mmu_fault(CPUState *cs, vaddr addr, int size,
 
             pml4e_addr = ((pml5e & PG_ADDRESS_MASK) +
                     (((addr >> 39) & 0x1ff) << 3)) & a20_mask;
+            pml4e_addr = get_hphys(cs, pml4e_addr, MMU_DATA_STORE, false);
             pml4e = x86_ldq_phys(cs, pml4e_addr);
             if (!(pml4e & PG_PRESENT_MASK)) {
                 goto do_fault;
@@ -257,6 +462,7 @@ int x86_cpu_handle_mmu_fault(CPUState *cs, vaddr addr, int size,
             ptep &= pml4e ^ PG_NX_MASK;
             pdpe_addr = ((pml4e & PG_ADDRESS_MASK) + (((addr >> 30) & 0x1ff) << 3)) &
                 a20_mask;
+            pdpe_addr = get_hphys(cs, pdpe_addr, MMU_DATA_STORE, NULL);
             pdpe = x86_ldq_phys(cs, pdpe_addr);
             if (!(pdpe & PG_PRESENT_MASK)) {
                 goto do_fault;
@@ -282,6 +488,7 @@ int x86_cpu_handle_mmu_fault(CPUState *cs, vaddr addr, int size,
             /* XXX: load them when cr3 is loaded ? */
             pdpe_addr = ((env->cr[3] & ~0x1f) + ((addr >> 27) & 0x18)) &
                 a20_mask;
+            pdpe_addr = get_hphys(cs, pdpe_addr, MMU_DATA_STORE, false);
             pdpe = x86_ldq_phys(cs, pdpe_addr);
             if (!(pdpe & PG_PRESENT_MASK)) {
                 goto do_fault;
@@ -295,6 +502,7 @@ int x86_cpu_handle_mmu_fault(CPUState *cs, vaddr addr, int size,
 
         pde_addr = ((pdpe & PG_ADDRESS_MASK) + (((addr >> 21) & 0x1ff) << 3)) &
             a20_mask;
+        pde_addr = get_hphys(cs, pde_addr, MMU_DATA_STORE, NULL);
         pde = x86_ldq_phys(cs, pde_addr);
         if (!(pde & PG_PRESENT_MASK)) {
             goto do_fault;
@@ -317,6 +525,7 @@ int x86_cpu_handle_mmu_fault(CPUState *cs, vaddr addr, int size,
         }
         pte_addr = ((pde & PG_ADDRESS_MASK) + (((addr >> 12) & 0x1ff) << 3)) &
             a20_mask;
+        pte_addr = get_hphys(cs, pte_addr, MMU_DATA_STORE, NULL);
         pte = x86_ldq_phys(cs, pte_addr);
         if (!(pte & PG_PRESENT_MASK)) {
             goto do_fault;
@@ -333,6 +542,7 @@ int x86_cpu_handle_mmu_fault(CPUState *cs, vaddr addr, int size,
         /* page directory entry */
         pde_addr = ((env->cr[3] & ~0xfff) + ((addr >> 20) & 0xffc)) &
             a20_mask;
+        pde_addr = get_hphys(cs, pde_addr, MMU_DATA_STORE, NULL);
         pde = x86_ldl_phys(cs, pde_addr);
         if (!(pde & PG_PRESENT_MASK)) {
             goto do_fault;
@@ -360,6 +570,7 @@ int x86_cpu_handle_mmu_fault(CPUState *cs, vaddr addr, int size,
         /* page directory entry */
         pte_addr = ((pde & ~0xfff) + ((addr >> 10) & 0xffc)) &
             a20_mask;
+        pte_addr = get_hphys(cs, pte_addr, MMU_DATA_STORE, NULL);
         pte = x86_ldl_phys(cs, pte_addr);
         if (!(pte & PG_PRESENT_MASK)) {
             goto do_fault;
@@ -442,12 +653,13 @@ do_check_protect_pse36:
 
     /* align to page_size */
     pte &= PG_ADDRESS_MASK & ~(page_size - 1);
+    page_offset = addr & (page_size - 1);
+    paddr = get_hphys(cs, pte + page_offset, is_write1, &prot);
 
     /* Even if 4MB pages, we map only one 4KB page in the cache to
        avoid filling it too fast */
     vaddr = addr & TARGET_PAGE_MASK;
-    page_offset = vaddr & (page_size - 1);
-    paddr = pte + page_offset;
+    paddr &= TARGET_PAGE_MASK;
 
     assert(prot & (1 << is_write1));
     tlb_set_page_with_attrs(cs, vaddr, paddr, cpu_get_mem_attrs(env),
diff --git a/target/i386/machine.c b/target/i386/machine.c
index 4d98d36..8b64dff 100644
--- a/target/i386/machine.c
+++ b/target/i386/machine.c
@@ -935,6 +935,26 @@ static const VMStateDescription vmstate_msr_virt_ssbd = {
     }
 };
 
+static bool svm_npt_needed(void *opaque)
+{
+    X86CPU *cpu = opaque;
+    CPUX86State *env = &cpu->env;
+
+    return !!(env->hflags2 & HF2_NPT_MASK);
+}
+
+static const VMStateDescription vmstate_svm_npt = {
+    .name = "cpu/svn_npt",
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .needed = svm_npt_needed,
+    .fields = (VMStateField[]){
+        VMSTATE_UINT64(env.nested_cr3, X86CPU),
+        VMSTATE_UINT32(env.nested_pg_mode, X86CPU),
+        VMSTATE_END_OF_LIST()
+    }
+};
+
 VMStateDescription vmstate_x86_cpu = {
     .name = "cpu",
     .version_id = 12,
@@ -1059,6 +1079,7 @@ VMStateDescription vmstate_x86_cpu = {
         &vmstate_mcg_ext_ctl,
         &vmstate_msr_intel_pt,
         &vmstate_msr_virt_ssbd,
+        &vmstate_svm_npt,
         NULL
     }
 };
diff --git a/target/i386/mem_helper.c b/target/i386/mem_helper.c
index a8ae694..30c26b9 100644
--- a/target/i386/mem_helper.c
+++ b/target/i386/mem_helper.c
@@ -202,13 +202,13 @@ void helper_boundl(CPUX86State *env, target_ulong a0, int v)
 void tlb_fill(CPUState *cs, target_ulong addr, int size,
               MMUAccessType access_type, int mmu_idx, uintptr_t retaddr)
 {
+    X86CPU *cpu = X86_CPU(cs);
+    CPUX86State *env = &cpu->env;
     int ret;
 
+    env->retaddr = retaddr;
     ret = x86_cpu_handle_mmu_fault(cs, addr, size, access_type, mmu_idx);
     if (ret) {
-        X86CPU *cpu = X86_CPU(cs);
-        CPUX86State *env = &cpu->env;
-
         raise_exception_err_ra(env, cs->exception_index, env->error_code, retaddr);
     }
 }
diff --git a/target/i386/svm.h b/target/i386/svm.h
index 922c8fd..23a3a04 100644
--- a/target/i386/svm.h
+++ b/target/i386/svm.h
@@ -130,6 +130,20 @@
 
 #define SVM_CR0_SELECTIVE_MASK (1 << 3 | 1) /* TS and MP */
 
+#define SVM_NPT_ENABLED     (1 << 0)
+
+#define SVM_NPT_PAE         (1 << 0)
+#define SVM_NPT_LMA         (1 << 1)
+#define SVM_NPT_NXE         (1 << 2)
+
+#define SVM_NPTEXIT_P       (1ULL << 0)
+#define SVM_NPTEXIT_RW      (1ULL << 1)
+#define SVM_NPTEXIT_US      (1ULL << 2)
+#define SVM_NPTEXIT_RSVD    (1ULL << 3)
+#define SVM_NPTEXIT_ID      (1ULL << 4)
+#define SVM_NPTEXIT_GPA     (1ULL << 32)
+#define SVM_NPTEXIT_GPT     (1ULL << 33)
+
 struct QEMU_PACKED vmcb_control_area {
 	uint16_t intercept_cr_read;
 	uint16_t intercept_cr_write;
diff --git a/target/i386/svm_helper.c b/target/i386/svm_helper.c
index f245aec..342ece0 100644
--- a/target/i386/svm_helper.c
+++ b/target/i386/svm_helper.c
@@ -124,6 +124,7 @@ void helper_vmrun(CPUX86State *env, int aflag, int next_eip_addend)
 {
     CPUState *cs = CPU(x86_env_get_cpu(env));
     target_ulong addr;
+    uint64_t nested_ctl;
     uint32_t event_inj;
     uint32_t int_ctl;
 
@@ -206,6 +207,26 @@ void helper_vmrun(CPUX86State *env, int aflag, int next_eip_addend)
                                                   control.intercept_exceptions
                                                   ));
 
+    nested_ctl = x86_ldq_phys(cs, env->vm_vmcb + offsetof(struct vmcb,
+                                                          control.nested_ctl));
+    if (nested_ctl & SVM_NPT_ENABLED) {
+        env->nested_cr3 = x86_ldq_phys(cs,
+                                env->vm_vmcb + offsetof(struct vmcb,
+                                                        control.nested_cr3));
+        env->hflags2 |= HF2_NPT_MASK;
+
+        env->nested_pg_mode = 0;
+        if (env->cr[4] & CR4_PAE_MASK) {
+            env->nested_pg_mode |= SVM_NPT_PAE;
+        }
+        if (env->hflags & HF_LMA_MASK) {
+            env->nested_pg_mode |= SVM_NPT_LMA;
+        }
+        if (env->efer & MSR_EFER_NXE) {
+            env->nested_pg_mode |= SVM_NPT_NXE;
+        }
+    }
+
     /* enable intercepts */
     env->hflags |= HF_SVMI_MASK;
 
@@ -616,6 +637,7 @@ void do_vmexit(CPUX86State *env, uint32_t exit_code, uint64_t exit_info_1)
         x86_stl_phys(cs,
                  env->vm_vmcb + offsetof(struct vmcb, control.int_state), 0);
     }
+    env->hflags2 &= ~HF2_NPT_MASK;
 
     /* Save the VM state in the vmcb */
     svm_save_seg(env, env->vm_vmcb + offsetof(struct vmcb, save.es),