From 25c2bce46a2639267d254ad3674c5cafb1fc970b Mon Sep 17 00:00:00 2001 From: Keir Fraser Date: Tue, 16 Dec 2008 11:54:11 +0000 Subject: [PATCH] vmx: Do not disable real EFER.NXE even when disabled by guest. We must not disable EFER.NXE in host mode since shadow code relies on accessing shadow mappings with NX set. We do not want to write EFER on every vmentry/vmexit if we can avoid it, since it will be somewhat slow. Finally, we don't believe that any guest relies on NX really being disabled when EFER.NXE is cleared. This given, it makes sense to ignore the guest's setting of EFER.NXE. Signed-off-by: Keir Fraser --- xen/arch/x86/hvm/vmx/vmx.c | 33 +++++++-------------------------- 1 file changed, 7 insertions(+), 26 deletions(-) diff --git a/xen/arch/x86/hvm/vmx/vmx.c b/xen/arch/x86/hvm/vmx/vmx.c index 1519a78d03..f065b45494 100644 --- a/xen/arch/x86/hvm/vmx/vmx.c +++ b/xen/arch/x86/hvm/vmx/vmx.c @@ -306,9 +306,6 @@ static void vmx_restore_host_msrs(void) wrmsrl(msr_index[i], host_msr_state->msrs[i]); clear_bit(i, &host_msr_state->flags); } - - if ( cpu_has_nx && !(read_efer() & EFER_NX) ) - write_efer(read_efer() | EFER_NX); } static void vmx_save_guest_msrs(struct vcpu *v) @@ -342,39 +339,23 @@ static void vmx_restore_guest_msrs(struct vcpu *v) clear_bit(i, &guest_flags); } - if ( (v->arch.hvm_vcpu.guest_efer ^ read_efer()) & (EFER_NX | EFER_SCE) ) + if ( (v->arch.hvm_vcpu.guest_efer ^ read_efer()) & EFER_SCE ) { HVM_DBG_LOG(DBG_LEVEL_2, "restore guest's EFER with value %lx", v->arch.hvm_vcpu.guest_efer); - write_efer((read_efer() & ~(EFER_NX | EFER_SCE)) | - (v->arch.hvm_vcpu.guest_efer & (EFER_NX | EFER_SCE))); + write_efer((read_efer() & ~EFER_SCE) | + (v->arch.hvm_vcpu.guest_efer & EFER_SCE)); } } #else /* __i386__ */ #define vmx_save_host_msrs() ((void)0) - -static void vmx_restore_host_msrs(void) -{ - if ( cpu_has_nx && !(read_efer() & EFER_NX) ) - write_efer(read_efer() | EFER_NX); -} +#define vmx_restore_host_msrs() ((void)0) #define vmx_save_guest_msrs(v) ((void)0) - -static void vmx_restore_guest_msrs(struct vcpu *v) -{ - if ( (v->arch.hvm_vcpu.guest_efer ^ read_efer()) & EFER_NX ) - { - HVM_DBG_LOG(DBG_LEVEL_2, - "restore guest's EFER with value %lx", - v->arch.hvm_vcpu.guest_efer); - write_efer((read_efer() & ~EFER_NX) | - (v->arch.hvm_vcpu.guest_efer & EFER_NX)); - } -} +#define vmx_restore_guest_msrs(v) ((void)0) static enum handler_return long_mode_do_msr_read(struct cpu_user_regs *regs) { @@ -1190,8 +1171,8 @@ static void vmx_update_guest_efer(struct vcpu *v) #endif if ( v == current ) - write_efer((read_efer() & ~(EFER_NX|EFER_SCE)) | - (v->arch.hvm_vcpu.guest_efer & (EFER_NX|EFER_SCE))); + write_efer((read_efer() & ~EFER_SCE) | + (v->arch.hvm_vcpu.guest_efer & EFER_SCE)); } static void vmx_flush_guest_tlbs(void) -- 2.30.2