From: Peter Dinda <pdinda@northwestern.edu>
Date: Mon, 26 May 2014 21:15:24 +0000 (-0500)
Subject: Convert shadow paging to use 32 PAE (VMX)
X-Git-Url: http://v3vee.org/palacios/gitweb/gitweb.cgi?p=palacios.git;a=commitdiff_plain;h=a7cacea293dbc2fbbbe36421054eff95f88390d4

Convert shadow paging to use 32 PAE (VMX)

This changes shadow paging to use, at minimum, 32PAE
shadow page tables.   This makes it possible to place
a guest using shadow paging anywhere in host physical
memory instead of just the first 4 GB

This patch adds support to VMX for this functionality:

- cr4 is read-shadowed to the shadow pager's guest cr4
- PAE is forced on
- vmx assist does not overwrite cr4 control, just masks it
- cleaner activation of passthrough PTs

Note that this is able to boot a BOCHS BIOS and a Linux guest.
It fails to boot the SEABIOS (Trap 0x8), but then that bug
is confirmed to be independent of these patches.
---

diff --git a/palacios/src/palacios/vmcs.c b/palacios/src/palacios/vmcs.c
index 2e4dcf3..4262aa8 100644
--- a/palacios/src/palacios/vmcs.c
+++ b/palacios/src/palacios/vmcs.c
@@ -228,7 +228,7 @@ int v3_vmx_save_vmcs(struct guest_info * info) {
     check_vmcs_read(VMCS_CR0_READ_SHDW, &(info->shdw_pg_state.guest_cr0));
     check_vmcs_read(VMCS_GUEST_CR3, &(info->ctrl_regs.cr3));
     check_vmcs_read(VMCS_GUEST_CR4, &(info->ctrl_regs.cr4));
-    check_vmcs_read(VMCS_CR4_READ_SHDW, &(vmx_info->guest_cr4));
+    check_vmcs_read(VMCS_CR4_READ_SHDW, &(info->shdw_pg_state.guest_cr4));
     check_vmcs_read(VMCS_GUEST_DR7, &(info->dbg_regs.dr7));
 
     check_vmcs_read(VMCS_GUEST_RFLAGS, &(info->ctrl_regs.rflags));
diff --git a/palacios/src/palacios/vmx.c b/palacios/src/palacios/vmx.c
index de81dfc..aba80c7 100644
--- a/palacios/src/palacios/vmx.c
+++ b/palacios/src/palacios/vmx.c
@@ -270,16 +270,19 @@ static int init_vmcs_bios(struct guest_info * core, struct vmx_data * vmx_state)
 
 
 	// Cause VM_EXIT whenever CR4.VMXE or CR4.PAE bits are written
-	vmx_ret |= check_vmcs_write(VMCS_CR4_MASK, CR4_VMXE | CR4_PAE);
+	vmx_ret |= check_vmcs_write(VMCS_CR4_MASK, CR4_VMXE | CR4_PAE );
 
-        core->ctrl_regs.cr3 = core->direct_map_pt;
+	v3_activate_passthrough_pt(core);
 
         // vmx_state->pinbased_ctrls |= NMI_EXIT;
 
         /* Add CR exits */
         vmx_state->pri_proc_ctrls.cr3_ld_exit = 1;
         vmx_state->pri_proc_ctrls.cr3_str_exit = 1;
-	
+
+	// Note that we intercept cr4.pae writes
+	// and we have cr4 read-shadowed to the shadow pager's cr4
+
 	vmx_state->pri_proc_ctrls.invlpg_exit = 1;
 	
 	/* Add page fault exits */
diff --git a/palacios/src/palacios/vmx_assist.c b/palacios/src/palacios/vmx_assist.c
index 3e1f7a7..fa67d97 100644
--- a/palacios/src/palacios/vmx_assist.c
+++ b/palacios/src/palacios/vmx_assist.c
@@ -248,10 +248,10 @@ int v3_vmxassist_init(struct guest_info * core, struct vmx_data * vmx_state) {
     core->vm_regs.rsp = 0x80000;
     ((struct rflags *)&(core->ctrl_regs.rflags))->rsvd1 = 1;
 
-#define GUEST_CR0 0x80010031
-#define GUEST_CR4 0x00002010
-    core->ctrl_regs.cr0 = GUEST_CR0;
-    core->ctrl_regs.cr4 = GUEST_CR4;
+#define GUEST_CR0_MASK 0x80010031
+#define GUEST_CR4_MASK 0x00002010
+    core->ctrl_regs.cr0 |= GUEST_CR0_MASK;
+    core->ctrl_regs.cr4 |= GUEST_CR4_MASK;
 
     ((struct cr0_32 *)&(core->shdw_pg_state.guest_cr0))->pe = 1;
     ((struct cr0_32 *)&(core->shdw_pg_state.guest_cr0))->wp = 1;