Per-processor GDT & IDT

Makefile

@@ -9,6 +9,7 @@ CFLAGS += -ggdb
 # preferentially in alphabetical order.
 VISOR_SOURCES_x86_64 := \
 	src/vintel.c \
+	src/proc.c \
 	# end of x86_64 specific sources list
 
 # Architecture-agnostic kernel sources.

include/x86/gdt.h

@@ -3,6 +3,18 @@
 
 #include <stdint.h>
 
+__attribute__ ((packed))
+struct segdescr {
+	uint16_t limit0;
+	uint16_t base0;
+	uint8_t  base1;
+	uint8_t  access;
+	uint8_t  flags;
+	uint16_t base2;
+	uint32_t base3;
+	uint32_t reserved;
+};
+
 __attribute__ ((packed))
 struct GDTR {
 	uint16_t limit;
@@ -17,4 +29,17 @@ storegdt(void)
 	return gdtr;
 }
 
+static inline void
+setsegdescr(struct segdescr *descr, uint64_t base, uint32_t limit, uint8_t access, uint8_t flags)
+{
+	descr->limit0   = limit;
+	descr->base0    = base;
+	descr->base1    = base >> 16;
+	descr->access   = access;
+	descr->flags    = flags | (limit >> 16);
+	descr->base2    = base >> 24;
+	descr->base3    = base >> 32;
+	descr->reserved = 0;
+}
+
 #endif

include/x86/idt.h

@@ -3,6 +3,17 @@
 
 #include <stdint.h>
 
+__attribute__ ((packed))
+struct intdescr {
+	uint16_t offset0;
+	uint16_t seg;
+	uint8_t  ist;
+	uint8_t  access;
+	uint16_t offset1;
+	uint32_t offset2;
+	uint32_t reserved;
+};
+
 __attribute__ ((packed))
 struct IDTR {
 	uint16_t limit;
@@ -17,4 +28,16 @@ storeidt(void)
 	return idtr;
 }
 
+static inline void
+setintdescr(struct intdescr *descr, uint64_t offset, uint16_t seg, uint8_t ist, uint8_t access)
+{
+	descr->offset0  = offset;
+	descr->seg      = seg;
+	descr->ist      = ist;
+	descr->access   = access;
+	descr->offset1  = offset >> 16;
+	descr->offset2  = offset >> 32;
+	descr->reserved = 0;
+}
+
 #endif

run.sh

@@ -0,0 +1,3 @@
+#!/bin/sh
+OVMF_BLOB=/usr/share/OVMF/x64/OVMF.fd
+uefi-run -d -b "$OVMF_BLOB" build/visor -- -enable-kvm -cpu host "$@"

src/bootstrap.h

@@ -0,0 +1,3 @@
+#include <stddef.h>
+
+void *bs_alloc(size_t size);

src/efi.c

@@ -4,18 +4,31 @@
 #include <efilib.h>
 
 #include "virt.h"
+#include "bootstrap.h"
+#include "procvisor.h"
 
 struct virt_vtable *virt = &virt_vtable_intel;
 
 static char virt_err[100];
 
+void *
+bs_alloc(size_t size)
+{
+	size_t npages = (size + (4096 - 1)) / 4096;
+	void *ptr;
+	uefi_call_wrapper(BS->AllocatePages, 4, AllocateAnyPages, EfiRuntimeServicesData, npages, &ptr);
+	return ptr;
+}
+
 EFIAPI
 EFI_STATUS
 efi_main(EFI_HANDLE imageHandle, EFI_SYSTEM_TABLE *systemTable)
 {
 	InitializeLib(imageHandle, systemTable);
 
-	Print(L"Hello, World!\n");
+	AsciiPrint("* Setting up processor structures\n");
+	struct procvisor *pv = proc_setup();
+	(void)pv;
 
 	AsciiPrint("* Checking for VT-x Support\n");
 	if (!virt->has_support(virt_err, sizeof virt_err)) {

src/proc.c

@@ -0,0 +1,62 @@
+#include <x86/idt.h>
+#include <x86/gdt.h>
+#include "procvisor.h"
+#include "bootstrap.h"
+
+#define GDT_SIZE (  3 * sizeof (struct segdescr))
+#define IDT_SIZE (256 * sizeof (struct intdescr))
+
+struct procvisor *procvisors[256];
+
+static void
+proc_fill_host_gdt(struct GDTR gdtr)
+{
+	struct segdescr *descrs = (void *)gdtr.base;
+	setsegdescr(&descrs[0], 0, 0, 0, 0); // null
+	setsegdescr(&descrs[1], 0, 0xffffff, 0x9B, 0xA0); // code
+	setsegdescr(&descrs[2], 0, 0xffffff, 0x93, 0xC0); // data
+}
+
+static void
+proc_fill_host_idt(struct IDTR idtr)
+{
+	struct intdescr *descrs = (void *)idtr.base;
+	for (int i = 0; i < 256; i++) {
+		setintdescr(&descrs[i], 0, 0, 0, 0);
+	}
+}
+
+struct procvisor *
+proc_setup(void)
+{
+	// Allocate 2M region for per-processor stuff
+	char *region = bs_alloc(PROC_REGION_SIZE);
+	char *top = region + PROC_REGION_SIZE;
+
+	// Carve out struct procvisor
+	top -= sizeof (struct procvisor);
+	struct procvisor *pv = (void *)top;
+
+	// Carve out GDT
+	top -= GDT_SIZE;
+	pv->host_gdtr.base  = (uintptr_t)top;
+	pv->host_gdtr.limit = GDT_SIZE - 1;
+
+	// Carve out IDT
+	top -= IDT_SIZE;
+	pv->host_idtr.base  = (uintptr_t)top;
+	pv->host_idtr.limit = IDT_SIZE - 1;
+
+	// Leave the rest as stack
+	top -= ((uintptr_t)top & 0xf); // align on 16-byte boundary
+	pv->host_stack = top;
+
+	// Fill out GDT & IDT structures
+	proc_fill_host_gdt(pv->host_gdtr);
+	proc_fill_host_idt(pv->host_idtr);
+
+	// Register procvisor & return
+	unsigned procid = myprocid();
+	procvisors[procid] = pv;
+	return pv;
+}

src/procvisor.h

@@ -0,0 +1,37 @@
+#include <stddef.h>
+#include <cpuid.h>
+#include <x86/gdt.h>
+#include <x86/idt.h>
+
+#define PROC_REGION_SIZE (512 * 4096)
+
+/* Per-processor visor state and structures */
+struct procvisor {
+	void *host_stack;
+	struct GDTR host_gdtr;
+	struct IDTR host_idtr;
+	//void *host_cr3;
+	//void *vmctl;
+};
+
+extern struct procvisor *procvisors[256];
+
+/* Get our own LAPIC ID -- the slow way ... */
+static inline unsigned
+myprocid(void)
+{
+	unsigned info[4];
+	__get_cpuid(0x1, &info[0], &info[1], &info[2], &info[3]);
+	unsigned procid = info[1] >> 24;
+	return procid;
+}
+
+static inline struct procvisor *
+myprocvisor(void)
+{
+	unsigned procid = myprocid();
+	if (procid >= 256) return NULL;
+	return procvisors[procid];
+}
+
+struct procvisor *proc_setup(void);

src/vintel.c

@@ -211,6 +211,7 @@ vintel_enable(void)
 		Print(L"Extended VMX Error\n");
 	}
 
+	// FIXME Allocate the correct amount of space!
 	Print(L"Allocating VMCS Page\n");
 	uefi_call_wrapper(BS->AllocatePages, 4, AllocateAnyPages, EfiRuntimeServicesData, 1, &vmcs_region);
 

src/vsegment.h

@@ -0,0 +1,5 @@
+struct vsegment {
+	uint64_t gpa;
+	uint64_t ha;
+	uint64_t count;
+};