From e8ea85fb280ec55674bca88ea7cd85f60d19567f Mon Sep 17 00:00:00 2001 From: Chenyi Qiang Date: Tue, 2 Feb 2021 17:04:32 +0800 Subject: KVM: X86: Add support for the emulation of DR6_BUS_LOCK bit Bus lock debug exception introduces a new bit DR6_BUS_LOCK (bit 11 of DR6) to indicate that bus lock #DB exception is generated. The set/clear of DR6_BUS_LOCK is similar to the DR6_RTM. The processor clears DR6_BUS_LOCK when the exception is generated. For all other #DB, the processor sets this bit to 1. Software #DB handler should set this bit before returning to the interrupted task. In VMM, to avoid breaking the CPUs without bus lock #DB exception support, activate the DR6_BUS_LOCK conditionally in DR6_FIXED_1 bits. When intercepting the #DB exception caused by bus locks, bit 11 of the exit qualification is set to identify it. The VMM should emulate the exception by clearing the bit 11 of the guest DR6. Co-developed-by: Xiaoyao Li Signed-off-by: Xiaoyao Li Signed-off-by: Chenyi Qiang Message-Id: <20210202090433.13441-3-chenyi.qiang@intel.com> Signed-off-by: Paolo Bonzini --- arch/x86/include/asm/kvm_host.h | 3 ++- arch/x86/kvm/x86.c | 3 +++ 2 files changed, 5 insertions(+), 1 deletion(-) (limited to 'arch/x86') diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index f85480b1d215..8836b3096217 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -200,6 +200,7 @@ enum x86_intercept_stage; #define KVM_NR_DB_REGS 4 +#define DR6_BUS_LOCK (1 << 11) #define DR6_BD (1 << 13) #define DR6_BS (1 << 14) #define DR6_BT (1 << 15) @@ -213,7 +214,7 @@ enum x86_intercept_stage; * DR6_ACTIVE_LOW is also used as the init/reset value for DR6. */ #define DR6_ACTIVE_LOW 0xffff0ff0 -#define DR6_VOLATILE 0x0001e00f +#define DR6_VOLATILE 0x0001e80f #define DR6_FIXED_1 (DR6_ACTIVE_LOW & ~DR6_VOLATILE) #define DR7_BP_EN_MASK 0x000000ff diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 4efd2978ec08..9b1a7040eae3 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -1176,6 +1176,9 @@ static u64 kvm_dr6_fixed(struct kvm_vcpu *vcpu) if (!guest_cpuid_has(vcpu, X86_FEATURE_RTM)) fixed |= DR6_RTM; + + if (!guest_cpuid_has(vcpu, X86_FEATURE_BUS_LOCK_DETECT)) + fixed |= DR6_BUS_LOCK; return fixed; } -- cgit