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vmx: implement long mode page table translation

This allows vmx to translate virtual addresses to physical
when the gues runs in long mode.

--- a/sys/src/cmd/vmx/x86.c

+++ b/sys/src/cmd/vmx/x86.c

@@ -60,10 +60,44 @@

 }

 static uintptr

-translate64(uintptr, uintptr *, int *)

+translate64(uintptr va, uintptr *pa, int *perm)

 {

-	vmerror("long mode translation not implemented");

-	return 0;	

+	void *pml4, *pdp, *pd, *pt;

+	u64int pml4e, pdpe, pde, pte;

+

+	pml4 = gptr(rget("cr3") & 0xffffffffff000ULL, 4096);

+	if(pml4 == nil) return 0;

+	pml4e = GET64(pml4, (va & (511ULL<<39)) >> (39-3));

+	if(perm != nil) *perm = pml4e & 15;

+	if((pml4e & 1) == 0) return 0;

+

+	pdp = gptr(pml4e & 0xffffffffff000ULL, 4096);

+	if(pdp == nil) return 0;

+	pdpe = GET64(pdp, (va & (511ULL<<30)) >> (30-3));

+	if((pdpe & 1) == 0) return 0;

+	if(perm != nil) *perm &= pdpe;

+	if((pdpe & 0x80) != 0){

+		*pa = (pdpe & 0xfffffc0000000ULL) | (va & 0x3fffffffULL);

+		return 0x40000000ULL - (va & 0x3fffffffULL);

+	}

+

+	pd = gptr(pdpe & 0xffffffffff000ULL, 4096);

+	if(pd == nil) return 0;

+	pde = GET64(pd, (va & (511ULL<<21)) >> (21-3));

+	if((pde & 1) == 0) return 0;

+	if(perm != nil) *perm &= pde;

+	if((pde & 0x80) != 0){

+		*pa = (pde & 0xfffffffe00000ULL) | (va & 0x1fffffULL);

+		return 0x200000ULL - (va & 0x1fffffULL);

+	}

+

+	pt = gptr(pde & 0xffffffffff000ULL, 4096);

+	if(pt == nil) return 0;

+	pte = GET64(pt, (va & (511ULL<<12)) >> (12-3));

+	if((pte & 1) == 0) return 0;

+	if(perm != nil) *perm &= pte;

+	*pa = (pte & 0xffffffffff000ULL) | (va & 0xfffULL);

+	return 0x1000ULL - (va & 0xfffULL);

 }

 static uintptr (*

@@ -229,6 +263,7 @@

 	cpl = rget("cs") & 3;

 	wp = (rget("cr0real") & 1<<16) != 0;

 	for(i = 0; i < sz; ){

+		pperm = 0;

 		l = translator()(addr+i, &pav, &pperm);

 		if(l == 0){

 		pf: