Re: [PATCH] nestedhvm: ASID emulation

[Christoph Egger <Christoph.Egger@amd.com>]

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Rebased due to change in previous patch.

On 04/13/11 12:37, Christoph Egger wrote:
>
> Implement ASID emulation.
> This allows the l1 guest to run the l2 guest using hw ASID.
>
> Signed-off-by: Christoph Egger<Christoph.Egger@amd.com>
>


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diff -r 5458a9862db2 -r c217f85d7d0a xen/arch/x86/hvm/asid.c
--- a/xen/arch/x86/hvm/asid.c
+++ b/xen/arch/x86/hvm/asid.c
@@ -102,10 +102,14 @@ void hvm_asid_flush_core(void)
     data->disabled = 1;
 }
 
-bool_t hvm_asid_handle_vmenter(void)
+bool_t hvm_asid_handle_vmenter(bool_t run_n2guest)
 {
+    int need_flush = 0;
     struct vcpu *curr = current;
     struct hvm_asid_data *data = &this_cpu(hvm_asid_data);
+    struct nestedvcpu *nv;
+
+    nv = &vcpu_nestedhvm(v);
 
     /* On erratum #170 systems we must flush the TLB. 
      * Generation overruns are taken here, too. */
@@ -113,27 +117,69 @@ bool_t hvm_asid_handle_vmenter(void)
         goto disabled;
 
     /* Test if VCPU has valid ASID. */
-    if ( curr->arch.hvm_vcpu.asid_generation == data->core_asid_generation )
-        return 0;
-
-    /* If there are no free ASIDs, need to go to a new generation */
-    if ( unlikely(data->next_asid > data->max_asid) )
-    {
-        hvm_asid_flush_core();
-        data->next_asid = 1;
-        if ( data->disabled )
-            goto disabled;
+    if ( curr->arch.hvm_vcpu.asid_generation == data->core_asid_generation ) {
+        if ( run_n2guest ) {
+            if ( !nv->nv_new_vasid && data->next_asid > nv->nv_n2asid ) {
+                /* l1 guest doesn't request a new asid */
+                /* When asid generation changed last time when we were
+                 * were going to run l1 guest then
+                 * next_asid <= nv->nv_n2asid.
+                 */
+                ASSERT(nv->nv_n2asid != 0);
+                ASSERT(nv->nv_n1asid != nv->nv_n2asid);
+                curr->arch.hvm_vcpu.asid = nv->nv_n2asid;
+                return 0;
+            }
+        } else if ( data->next_asid > nv->nv_n1asid ) {
+            /* When asid generation changed last time when we were going to
+             * run l2 guest then next_asid <= nv->nv_n1asid.
+             */
+            ASSERT(nv->nv_n1asid != 0);
+            ASSERT(nv->nv_n1asid != nv->nv_n2asid);
+            curr->arch.hvm_vcpu.asid = nv->nv_n1asid;
+            return 0;
+        }
     }
 
-    /* Now guaranteed to be a free ASID. */
-    curr->arch.hvm_vcpu.asid = data->next_asid++;
+    do {
+        /* If there are no free ASIDs, need to go to a new generation */
+        if ( unlikely(data->next_asid > data->max_asid) )
+        {
+            hvm_asid_flush_core();
+            data->next_asid = 1;
+            if ( data->disabled )
+                goto disabled;
+        }
+
+        if ( data->next_asid == 1 ) {
+            /* We start a new generation, so all old ASID allocations are
+             * stale now. Ensure we flush the TLB also in case of another
+             * iteration.
+             */
+            need_flush = 1;
+        }
+
+        /* Now guaranteed to be a free ASID. */
+        if ( run_n2guest )
+            /* nv_n1asid might have an asid from an old generation.
+             * We handle this on next vmenter.
+             */
+            nv->nv_n2asid = data->next_asid++;
+        else
+            /* nv_n2asid might have an asid from an old generation.
+             * We handle this on next vmenter.
+             */
+            nv->nv_n1asid = data->next_asid++;
+
+        /* Make sure an asid isn't used twice */
+    } while (nv->nv_n2asid == nv->nv_n1asid);
+
+    ASSERT(nv->nv_n1asid != 0);
+
+    curr->arch.hvm_vcpu.asid = (run_n2guest) ? nv->nv_n2asid : nv->nv_n1asid;
     curr->arch.hvm_vcpu.asid_generation = data->core_asid_generation;
 
-    /*
-     * When we assign ASID 1, flush all TLB entries as we are starting a new
-     * generation, and all old ASID allocations are now stale. 
-     */
-    return (curr->arch.hvm_vcpu.asid == 1);
+    return need_flush;
 
  disabled:
     curr->arch.hvm_vcpu.asid = 0;
diff -r 5458a9862db2 -r c217f85d7d0a xen/arch/x86/hvm/nestedhvm.c
--- a/xen/arch/x86/hvm/nestedhvm.c
+++ b/xen/arch/x86/hvm/nestedhvm.c
@@ -61,6 +61,9 @@ nestedhvm_vcpu_reset(struct vcpu *v)
     nv->nv_vvmcxaddr = VMCX_EADDR;
     nv->nv_flushp2m = 0;
     nv->nv_p2m = NULL;
+    nv->nv_new_vasid = 0;
+    nv->nv_n1asid = 0;
+    nv->nv_n2asid = 0;
 
     if ( hvm_funcs.nhvm_vcpu_reset )
         hvm_funcs.nhvm_vcpu_reset(v);
diff -r 5458a9862db2 -r c217f85d7d0a xen/arch/x86/hvm/svm/asid.c
--- a/xen/arch/x86/hvm/svm/asid.c
+++ b/xen/arch/x86/hvm/svm/asid.c
@@ -22,6 +22,7 @@
 #include <xen/perfc.h>
 #include <asm/hvm/svm/asid.h>
 #include <asm/amd.h>
+#include <asm/hvm/nestedhvm.h>
 
 void svm_asid_init(struct cpuinfo_x86 *c)
 {
@@ -42,7 +43,13 @@ asmlinkage void svm_asid_handle_vmrun(vo
 {
     struct vcpu *curr = current;
     struct vmcb_struct *vmcb = curr->arch.hvm_svm.vmcb;
-    bool_t need_flush = hvm_asid_handle_vmenter();
+    bool_t need_flush;
+    bool_t vcpu_guestmode = 0;
+
+    if ( nestedhvm_enabled(curr->domain) && nestedhvm_vcpu_in_guestmode(curr) )
+        vcpu_guestmode = 1;
+
+    need_flush = hvm_asid_handle_vmenter(vcpu_guestmode);
 
     /* ASID 0 indicates that ASIDs are disabled. */
     if ( curr->arch.hvm_vcpu.asid == 0 )
diff -r 5458a9862db2 -r c217f85d7d0a xen/arch/x86/hvm/svm/nestedsvm.c
--- a/xen/arch/x86/hvm/svm/nestedsvm.c
+++ b/xen/arch/x86/hvm/svm/nestedsvm.c
@@ -261,8 +261,6 @@ int nsvm_vcpu_hostrestore(struct vcpu *v
     /* Cleanbits */
     n1vmcb->cleanbits.bytes = 0;
 
-    hvm_asid_flush_vcpu(v);
-
     return 0;
 }
 
@@ -408,9 +406,7 @@ static int nsvm_vmcb_prepare4vmrun(struc
     if (rc)
         return rc;
 
-    /* ASID */
-    hvm_asid_flush_vcpu(v);
-    /* n2vmcb->_guest_asid = ns_vmcb->_guest_asid; */
+    /* ASID - Emulation handled in hvm_asid_handle_vmenter() */
 
     /* TLB control */
     n2vmcb->tlb_control = n1vmcb->tlb_control | ns_vmcb->tlb_control;
@@ -605,8 +601,8 @@ nsvm_vcpu_vmentry(struct vcpu *v, struct
     svm->ns_vmcb_guestcr3 = ns_vmcb->_cr3;
     svm->ns_vmcb_hostcr3 = ns_vmcb->_h_cr3;
 
-    nv->nv_flushp2m = (ns_vmcb->tlb_control
-        || (svm->ns_guest_asid != ns_vmcb->_guest_asid));
+    nv->nv_new_vasid = (svm->ns_guest_asid != ns_vmcb->_guest_asid);
+    nv->nv_flushp2m = (ns_vmcb->tlb_control || nv->nv_new_vasid);
     svm->ns_guest_asid = ns_vmcb->_guest_asid;
 
     /* nested paging for the guest */
diff -r 5458a9862db2 -r c217f85d7d0a xen/arch/x86/hvm/svm/svm.c
--- a/xen/arch/x86/hvm/svm/svm.c
+++ b/xen/arch/x86/hvm/svm/svm.c
@@ -1580,6 +1580,17 @@ static void svm_vmexit_do_invalidate_cac
     __update_guest_eip(regs, inst_len);
 }
 
+static void svm_invlpga_intercept(struct vcpu *v,
+    unsigned long vaddr, uint32_t asid)
+{
+    struct nestedvcpu *nv = &vcpu_nestedhvm(v);
+    if (asid == 0)
+       asid = nv->nv_n1asid; /* remap to l1 guest asid */
+    else
+       asid = nv->nv_n2asid; /* remap to l2 guest asid */
+    svm_invlpga(vaddr, asid);
+}
+
 static void svm_invlpg_intercept(unsigned long vaddr)
 {
     struct vcpu *curr = current;
@@ -1892,10 +1903,12 @@ asmlinkage void svm_vmexit_handler(struc
     case VMEXIT_CR0_READ ... VMEXIT_CR15_READ:
     case VMEXIT_CR0_WRITE ... VMEXIT_CR15_WRITE:
     case VMEXIT_INVLPG:
-    case VMEXIT_INVLPGA:
         if ( !handle_mmio() )
             hvm_inject_exception(TRAP_gp_fault, 0, 0);
         break;
+    case VMEXIT_INVLPGA:
+        svm_invlpga_intercept(v, regs->rax, regs->ecx);
+        break;
 
     case VMEXIT_VMMCALL:
         if ( (inst_len = __get_instruction_length(v, INSTR_VMCALL)) == 0 )
diff -r 5458a9862db2 -r c217f85d7d0a xen/arch/x86/hvm/vmx/vmx.c
--- a/xen/arch/x86/hvm/vmx/vmx.c
+++ b/xen/arch/x86/hvm/vmx/vmx.c
@@ -2673,7 +2673,7 @@ asmlinkage void vmx_vmenter_helper(void)
         goto out;
 
     old_asid = curr->arch.hvm_vcpu.asid;
-    need_flush = hvm_asid_handle_vmenter();
+    need_flush = hvm_asid_handle_vmenter(0 /* false */);
     new_asid = curr->arch.hvm_vcpu.asid;
 
     if ( unlikely(new_asid != old_asid) )
diff -r 5458a9862db2 -r c217f85d7d0a xen/include/asm-x86/hvm/asid.h
--- a/xen/include/asm-x86/hvm/asid.h
+++ b/xen/include/asm-x86/hvm/asid.h
@@ -35,7 +35,7 @@ void hvm_asid_flush_core(void);
 
 /* Called before entry to guest context. Checks ASID allocation, returns a
  * boolean indicating whether all ASIDs must be flushed. */
-bool_t hvm_asid_handle_vmenter(void);
+bool_t hvm_asid_handle_vmenter(bool_t run_n2guest);
 
 #endif /* __ASM_X86_HVM_ASID_H__ */
 
diff -r 5458a9862db2 -r c217f85d7d0a xen/include/asm-x86/hvm/vcpu.h
--- a/xen/include/asm-x86/hvm/vcpu.h
+++ b/xen/include/asm-x86/hvm/vcpu.h
@@ -49,6 +49,11 @@ struct nestedvcpu {
     uint64_t nv_n1vmcx_pa; /* host physical address of nv_n1vmcx */
     uint64_t nv_n2vmcx_pa; /* host physical address of nv_n2vmcx */
 
+    /* ASID emulation */
+    bool_t nv_new_vasid;   /* true when l1 guest requests new virtual asid */
+    uint32_t nv_n1asid;    /* hw ASID number used to run l1 guest */
+    uint32_t nv_n2asid;    /* hw ASID number used to run l2 guest */
+
     /* SVM/VMX arch specific */
     union {
         struct nestedsvm nsvm;

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