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Force certain bits in %cr4 to be hard-wired to '1' or '0' from a guest's

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perspective. If we don't do this some guest OSes (e.g. Linux) will reset
the CR4_VMXE bit in %cr4 with disastrous consequences.

Reported by: grehan
This commit is contained in:
Neel Natu 2012-08-04 02:06:55 +00:00
parent 2bdc0d011a
commit 39c21c2db2
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/projects/bhyve/; revision=239024
1 changed files with 52 additions and 16 deletions
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68
sys/amd64/vmm/intel/vmx.c
View file

@ -627,23 +627,38 @@ vmx_vpid(void)
}
static int
vmx_setup_cr0_shadow(struct vmcs *vmcs)
vmx_setup_cr_shadow(int which, struct vmcs *vmcs)
{
int error;
uint64_t mask, shadow;
int error, mask_ident, shadow_ident;
uint64_t mask_value, shadow_value;
mask = cr0_ones_mask | cr0_zeros_mask;
error = vmcs_setreg(vmcs, VMCS_IDENT(VMCS_CR0_MASK), mask);
if (which != 0 && which != 4)
panic("vmx_setup_cr_shadow: unknown cr%d", which);
if (which == 0) {
mask_ident = VMCS_CR0_MASK;
mask_value = cr0_ones_mask | cr0_zeros_mask;
shadow_ident = VMCS_CR0_SHADOW;
shadow_value = cr0_ones_mask;
} else {
mask_ident = VMCS_CR4_MASK;
mask_value = cr4_ones_mask | cr4_zeros_mask;
shadow_ident = VMCS_CR4_SHADOW;
shadow_value = cr4_ones_mask;
}
error = vmcs_setreg(vmcs, VMCS_IDENT(mask_ident), mask_value);
if (error)
return (error);
shadow = cr0_ones_mask;
error = vmcs_setreg(vmcs, VMCS_IDENT(VMCS_CR0_SHADOW), shadow);
error = vmcs_setreg(vmcs, VMCS_IDENT(shadow_ident), shadow_value);
if (error)
return (error);
return (0);
}
#define vmx_setup_cr0_shadow(vmcs) vmx_setup_cr_shadow(0, (vmcs))
#define vmx_setup_cr4_shadow(vmcs) vmx_setup_cr_shadow(4, (vmcs))
static void *
vmx_vminit(struct vm *vm)
@ -744,6 +759,12 @@ vmx_vminit(struct vm *vm)
panic("vmcs_set_msr_save error %d", error);
error = vmx_setup_cr0_shadow(&vmx->vmcs[i]);
if (error != 0)
panic("vmx_setup_cr0_shadow %d", error);
error = vmx_setup_cr4_shadow(&vmx->vmcs[i]);
if (error != 0)
panic("vmx_setup_cr4_shadow %d", error);
}
return (vmx);
@ -1031,12 +1052,16 @@ vmx_inject_interrupts(struct vmx *vmx, int vcpu)
static int
vmx_emulate_cr_access(struct vmx *vmx, int vcpu, uint64_t exitqual)
{
int error;
uint64_t regval;
int error, cr, vmcs_guest_cr;
uint64_t regval, ones_mask, zeros_mask;
const struct vmxctx *vmxctx;
/* We only handle mov to %cr0 at this time */
if ((exitqual & 0xff) != 0x00)
/* We only handle mov to %cr0 or %cr4 at this time */
if ((exitqual & 0xf0) != 0x00)
return (UNHANDLED);
cr = exitqual & 0xf;
if (cr != 0 && cr != 4)
return (UNHANDLED);
vmxctx = &vmx->ctx[vcpu];
@ -1100,11 +1125,22 @@ vmx_emulate_cr_access(struct vmx *vmx, int vcpu, uint64_t exitqual)
break;
}
regval |= cr0_ones_mask;
regval &= ~cr0_zeros_mask;
error = vmwrite(VMCS_GUEST_CR0, regval);
if (error)
panic("vmx_emulate_cr_access: error %d writing cr0", error);
if (cr == 0) {
ones_mask = cr0_ones_mask;
zeros_mask = cr0_zeros_mask;
vmcs_guest_cr = VMCS_GUEST_CR0;
} else {
ones_mask = cr4_ones_mask;
zeros_mask = cr4_zeros_mask;
vmcs_guest_cr = VMCS_GUEST_CR4;
}
regval |= ones_mask;
regval &= ~zeros_mask;
error = vmwrite(vmcs_guest_cr, regval);
if (error) {
panic("vmx_emulate_cr_access: error %d writing cr%d",
error, cr);
}
return (HANDLED);
}