diff options
Diffstat (limited to 'arch/x86/include')
| -rw-r--r-- | arch/x86/include/asm/debugreg.h | 19 | ||||
| -rw-r--r-- | arch/x86/include/asm/kvm_host.h | 2 | ||||
| -rw-r--r-- | arch/x86/include/uapi/asm/debugreg.h | 21 |
3 files changed, 36 insertions, 6 deletions
diff --git a/arch/x86/include/asm/debugreg.h b/arch/x86/include/asm/debugreg.h index 363110e6b2e3..a2c1f2d24b64 100644 --- a/arch/x86/include/asm/debugreg.h +++ b/arch/x86/include/asm/debugreg.h @@ -9,6 +9,14 @@ #include <asm/cpufeature.h> #include <asm/msr.h> +/* + * Define bits that are always set to 1 in DR7, only bit 10 is + * architecturally reserved to '1'. + * + * This is also the init/reset value for DR7. + */ +#define DR7_FIXED_1 0x00000400 + DECLARE_PER_CPU(unsigned long, cpu_dr7); #ifndef CONFIG_PARAVIRT_XXL @@ -100,8 +108,8 @@ static __always_inline void native_set_debugreg(int regno, unsigned long value) static inline void hw_breakpoint_disable(void) { - /* Zero the control register for HW Breakpoint */ - set_debugreg(0UL, 7); + /* Reset the control register for HW Breakpoint */ + set_debugreg(DR7_FIXED_1, 7); /* Zero-out the individual HW breakpoint address registers */ set_debugreg(0UL, 0); @@ -125,9 +133,12 @@ static __always_inline unsigned long local_db_save(void) return 0; get_debugreg(dr7, 7); - dr7 &= ~0x400; /* architecturally set bit */ + + /* Architecturally set bit */ + dr7 &= ~DR7_FIXED_1; if (dr7) - set_debugreg(0, 7); + set_debugreg(DR7_FIXED_1, 7); + /* * Ensure the compiler doesn't lower the above statements into * the critical section; disabling breakpoints late would not diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index b4a391929cdb..639d9bcee842 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -31,6 +31,7 @@ #include <asm/apic.h> #include <asm/pvclock-abi.h> +#include <asm/debugreg.h> #include <asm/desc.h> #include <asm/mtrr.h> #include <asm/msr-index.h> @@ -249,7 +250,6 @@ enum x86_intercept_stage; #define DR7_BP_EN_MASK 0x000000ff #define DR7_GE (1 << 9) #define DR7_GD (1 << 13) -#define DR7_FIXED_1 0x00000400 #define DR7_VOLATILE 0xffff2bff #define KVM_GUESTDBG_VALID_MASK \ diff --git a/arch/x86/include/uapi/asm/debugreg.h b/arch/x86/include/uapi/asm/debugreg.h index 0007ba077c0c..41da492dfb01 100644 --- a/arch/x86/include/uapi/asm/debugreg.h +++ b/arch/x86/include/uapi/asm/debugreg.h @@ -15,7 +15,26 @@ which debugging register was responsible for the trap. The other bits are either reserved or not of interest to us. */ -/* Define reserved bits in DR6 which are always set to 1 */ +/* + * Define bits in DR6 which are set to 1 by default. + * + * This is also the DR6 architectural value following Power-up, Reset or INIT. + * + * Note, with the introduction of Bus Lock Detection (BLD) and Restricted + * Transactional Memory (RTM), the DR6 register has been modified: + * + * 1) BLD flag (bit 11) is no longer reserved to 1 if the CPU supports + * Bus Lock Detection. The assertion of a bus lock could clear it. + * + * 2) RTM flag (bit 16) is no longer reserved to 1 if the CPU supports + * restricted transactional memory. #DB occurred inside an RTM region + * could clear it. + * + * Apparently, DR6.BLD and DR6.RTM are active low bits. + * + * As a result, DR6_RESERVED is an incorrect name now, but it is kept for + * compatibility. + */ #define DR6_RESERVED (0xFFFF0FF0) #define DR_TRAP0 (0x1) /* db0 */ |