From: Chenyi Qiang chenyi.qiang@intel.com
mainline inclusion from mainline-v5.12 commit e8ea85fb280ec55674bca88ea7cd85f60d19567f category: feature bugzilla: https://gitee.com/openeuler/kernel/issues/I5OD9N CVE: NA
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...
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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 xiaoyao.li@intel.com Signed-off-by: Xiaoyao Li xiaoyao.li@intel.com Signed-off-by: Chenyi Qiang chenyi.qiang@intel.com Message-Id: 20210202090433.13441-3-chenyi.qiang@intel.com Signed-off-by: Paolo Bonzini pbonzini@redhat.com Signed-off-by: Zhou Shuling zhoushuling@huawei.com --- arch/x86/include/asm/kvm_host.h | 3 ++- arch/x86/kvm/x86.c | 3 +++ 2 files changed, 5 insertions(+), 1 deletion(-)
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index 226fa7354e79..fde1b52a8b2e 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -199,6 +199,7 @@ 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) @@ -212,7 +213,7 @@ 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 06f7ea7a7748..05cd09334d9d 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -1175,6 +1175,9 @@ 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; }