[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [xen master] x86/vmx: Partially revert "x86/vmx: implement Notify VM Exit"
commit 5f08bc9404c7cfa8131e262c7dbcb4d96c752686 Author: Andrew Cooper <andrew.cooper3@xxxxxxxxxx> AuthorDate: Wed Jan 18 19:20:05 2023 +0000 Commit: Andrew Cooper <andrew.cooper3@xxxxxxxxxx> CommitDate: Fri Jan 20 19:39:32 2023 +0000 x86/vmx: Partially revert "x86/vmx: implement Notify VM Exit" The original patch tried to do two things - implement VMNotify, and re-optimise VT-x to not intercept #DB/#AC by default. The second part is buggy in multiple ways. Both GDBSX and Introspection need to conditionally intercept #DB, which was not accounted for. Also, #DB interception has nothing at all to do with cpu_has_monitor_trap_flag. Revert the second half, leaving #DB/#AC intercepted unilaterally, but with VMNotify active by default when available. Fixes: 573279cde1c4 ("x86/vmx: implement Notify VM Exit") Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx> Reviewed-by: Kevin Tian <kevin.tian@xxxxxxxxx> --- xen/arch/x86/hvm/vmx/vmcs.c | 11 ++--------- xen/arch/x86/hvm/vmx/vmx.c | 16 ++-------------- 2 files changed, 4 insertions(+), 23 deletions(-) diff --git a/xen/arch/x86/hvm/vmx/vmcs.c b/xen/arch/x86/hvm/vmx/vmcs.c index 8992f4e0ae..7d8bfeb539 100644 --- a/xen/arch/x86/hvm/vmx/vmcs.c +++ b/xen/arch/x86/hvm/vmx/vmcs.c @@ -1296,17 +1296,10 @@ static int construct_vmcs(struct vcpu *v) v->arch.hvm.vmx.exception_bitmap = HVM_TRAP_MASK | (paging_mode_hap(d) ? 0 : (1U << TRAP_page_fault)) | (v->arch.fully_eager_fpu ? 0 : (1U << TRAP_no_device)); + if ( cpu_has_vmx_notify_vm_exiting ) - { __vmwrite(NOTIFY_WINDOW, vm_notify_window); - /* - * Disable #AC and #DB interception: by using VM Notify Xen is - * guaranteed to get a VM exit even if the guest manages to lock the - * CPU. - */ - v->arch.hvm.vmx.exception_bitmap &= ~((1U << TRAP_debug) | - (1U << TRAP_alignment_check)); - } + vmx_update_exception_bitmap(v); v->arch.hvm.guest_cr[0] = X86_CR0_PE | X86_CR0_ET; diff --git a/xen/arch/x86/hvm/vmx/vmx.c b/xen/arch/x86/hvm/vmx/vmx.c index 15a07933ee..2e2ab0ac0e 100644 --- a/xen/arch/x86/hvm/vmx/vmx.c +++ b/xen/arch/x86/hvm/vmx/vmx.c @@ -1564,19 +1564,10 @@ static void cf_check vmx_update_host_cr3(struct vcpu *v) void vmx_update_debug_state(struct vcpu *v) { - unsigned int mask = 1u << TRAP_int3; - - if ( !cpu_has_monitor_trap_flag && cpu_has_vmx_notify_vm_exiting ) - /* - * Only allow toggling TRAP_debug if notify VM exit is enabled, as - * unconditionally setting TRAP_debug is part of the XSA-156 fix. - */ - mask |= 1u << TRAP_debug; - if ( v->arch.hvm.debug_state_latch ) - v->arch.hvm.vmx.exception_bitmap |= mask; + v->arch.hvm.vmx.exception_bitmap |= 1U << TRAP_int3; else - v->arch.hvm.vmx.exception_bitmap &= ~mask; + v->arch.hvm.vmx.exception_bitmap &= ~(1U << TRAP_int3); vmx_vmcs_enter(v); vmx_update_exception_bitmap(v); @@ -4192,9 +4183,6 @@ void vmx_vmexit_handler(struct cpu_user_regs *regs) switch ( vector ) { case TRAP_debug: - if ( cpu_has_monitor_trap_flag && cpu_has_vmx_notify_vm_exiting ) - goto exit_and_crash; - /* * Updates DR6 where debugger can peek (See 3B 23.2.1, * Table 23-1, "Exit Qualification for Debug Exceptions"). -- generated by git-patchbot for /home/xen/git/xen.git#master
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