diff mbox series

[v3,1/2] KVM: arm64: Make PMEVTYPER<n>_EL0.NSH RES0 if EL2 isn't advertised

Message ID 20231019185618.3442949-2-oliver.upton@linux.dev (mailing list archive)
State New, archived
Headers show
Series KVM: arm64: PMU event filtering fixes | expand

Commit Message

Oliver Upton Oct. 19, 2023, 6:56 p.m. UTC 
The NSH bit, which filters event counting at EL2, is required by the
architecture if an implementation has EL2. Even though KVM doesn't
support nested virt yet, it makes no effort to hide the existence of EL2
from the ID registers. Userspace can, however, change the value of PFR0
to hide EL2. Align KVM's sysreg emulation with the architecture and make
NSH RES0 if EL2 isn't advertised. Keep in mind the bit is ignored when
constructing the backing perf event.

While at it, build the event type mask using explicit field definitions
instead of relying on ARMV8_PMU_EVTYPE_MASK. KVM probably should've been
doing this in the first place, as it avoids changes to the
aforementioned mask affecting sysreg emulation.

Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
---
 arch/arm64/kvm/pmu-emul.c | 21 ++++++++++++++-------
 arch/arm64/kvm/sys_regs.c |  8 ++++++--
 include/kvm/arm_pmu.h     |  5 +++++
 3 files changed, 25 insertions(+), 9 deletions(-)

Comments

kernel test robot Oct. 24, 2023, 2:47 a.m. UTC | #1 
Hi Oliver,

kernel test robot noticed the following build errors:

[auto build test ERROR on 6465e260f48790807eef06b583b38ca9789b6072]

url:    https://github.com/intel-lab-lkp/linux/commits/Oliver-Upton/KVM-arm64-Make-PMEVTYPER-n-_EL0-NSH-RES0-if-EL2-isn-t-advertised/20231020-025836
base:   6465e260f48790807eef06b583b38ca9789b6072
patch link:    https://lore.kernel.org/r/20231019185618.3442949-2-oliver.upton%40linux.dev
patch subject: [PATCH v3 1/2] KVM: arm64: Make PMEVTYPER<n>_EL0.NSH RES0 if EL2 isn't advertised
config: arm64-randconfig-004-20231023 (https://download.01.org/0day-ci/archive/20231024/202310241025.FmLnpSTG-lkp@intel.com/config)
compiler: aarch64-linux-gcc (GCC) 13.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20231024/202310241025.FmLnpSTG-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202310241025.FmLnpSTG-lkp@intel.com/

All errors (new ones prefixed by >>):

   arch/arm64/kvm/sys_regs.c: In function 'reset_pmevtyper':
>> arch/arm64/kvm/sys_regs.c:754:41: error: too many arguments to function 'kvm_pmu_evtyper_mask'
     754 |         __vcpu_sys_reg(vcpu, r->reg) &= kvm_pmu_evtyper_mask(vcpu->kvm);
         |                                         ^~~~~~~~~~~~~~~~~~~~
   In file included from arch/arm64/include/asm/kvm_host.h:37,
                    from include/linux/kvm_host.h:45,
                    from arch/arm64/kvm/sys_regs.c:15:
   include/kvm/arm_pmu.h:176:19: note: declared here
     176 | static inline u64 kvm_pmu_evtyper_mask(void)
         |                   ^~~~~~~~~~~~~~~~~~~~
   arch/arm64/kvm/sys_regs.c: At top level:
   arch/arm64/kvm/sys_regs.c:2174:20: warning: initialized field overwritten [-Woverride-init]
    2174 |           .reset = reset_pmcr, .reg = PMCR_EL0 },
         |                    ^~~~~~~~~~
   arch/arm64/kvm/sys_regs.c:2174:20: note: (near initialization for 'sys_reg_descs[233].reset')
   In file included from include/uapi/linux/posix_types.h:5,
                    from include/uapi/linux/types.h:14,
                    from include/linux/types.h:6,
                    from include/linux/kasan-checks.h:5,
                    from include/asm-generic/rwonce.h:26,
                    from arch/arm64/include/asm/rwonce.h:71,
                    from include/linux/compiler.h:246,
                    from include/linux/build_bug.h:5,
                    from include/linux/bitfield.h:10,
                    from arch/arm64/kvm/sys_regs.c:12:
   include/linux/stddef.h:8:14: warning: initialized field overwritten [-Woverride-init]
       8 | #define NULL ((void *)0)
         |              ^
   arch/arm64/kvm/sys_regs.c:2187:46: note: in expansion of macro 'NULL'
    2187 |           .access = access_pmswinc, .reset = NULL },
         |                                              ^~~~
   include/linux/stddef.h:8:14: note: (near initialization for 'sys_reg_descs[237].reset')
       8 | #define NULL ((void *)0)
         |              ^
   arch/arm64/kvm/sys_regs.c:2187:46: note: in expansion of macro 'NULL'
    2187 |           .access = access_pmswinc, .reset = NULL },
         |                                              ^~~~
   arch/arm64/kvm/sys_regs.c:2189:45: warning: initialized field overwritten [-Woverride-init]
    2189 |           .access = access_pmselr, .reset = reset_pmselr, .reg = PMSELR_EL0 },
         |                                             ^~~~~~~~~~~~
   arch/arm64/kvm/sys_regs.c:2189:45: note: (near initialization for 'sys_reg_descs[238].reset')
   include/linux/stddef.h:8:14: warning: initialized field overwritten [-Woverride-init]
       8 | #define NULL ((void *)0)
         |              ^
   arch/arm64/kvm/sys_regs.c:2191:45: note: in expansion of macro 'NULL'
    2191 |           .access = access_pmceid, .reset = NULL },
         |                                             ^~~~
   include/linux/stddef.h:8:14: note: (near initialization for 'sys_reg_descs[239].reset')
       8 | #define NULL ((void *)0)
         |              ^
   arch/arm64/kvm/sys_regs.c:2191:45: note: in expansion of macro 'NULL'
    2191 |           .access = access_pmceid, .reset = NULL },
         |                                             ^~~~
   include/linux/stddef.h:8:14: warning: initialized field overwritten [-Woverride-init]
       8 | #define NULL ((void *)0)
         |              ^
   arch/arm64/kvm/sys_regs.c:2193:45: note: in expansion of macro 'NULL'
    2193 |           .access = access_pmceid, .reset = NULL },
         |                                             ^~~~
   include/linux/stddef.h:8:14: note: (near initialization for 'sys_reg_descs[240].reset')
       8 | #define NULL ((void *)0)
         |              ^
   arch/arm64/kvm/sys_regs.c:2193:45: note: in expansion of macro 'NULL'
    2193 |           .access = access_pmceid, .reset = NULL },
         |                                             ^~~~
   arch/arm64/kvm/sys_regs.c:2195:49: warning: initialized field overwritten [-Woverride-init]
    2195 |           .access = access_pmu_evcntr, .reset = reset_unknown,
         |                                                 ^~~~~~~~~~~~~
   arch/arm64/kvm/sys_regs.c:2195:49: note: (near initialization for 'sys_reg_descs[241].reset')
   include/linux/stddef.h:8:14: warning: initialized field overwritten [-Woverride-init]
       8 | #define NULL ((void *)0)
         |              ^
   arch/arm64/kvm/sys_regs.c:2198:50: note: in expansion of macro 'NULL'
    2198 |           .access = access_pmu_evtyper, .reset = NULL },
         |                                                  ^~~~
   include/linux/stddef.h:8:14: note: (near initialization for 'sys_reg_descs[242].reset')
       8 | #define NULL ((void *)0)
         |              ^
   arch/arm64/kvm/sys_regs.c:2198:50: note: in expansion of macro 'NULL'
    2198 |           .access = access_pmu_evtyper, .reset = NULL },
         |                                                  ^~~~
   include/linux/stddef.h:8:14: warning: initialized field overwritten [-Woverride-init]
       8 | #define NULL ((void *)0)
         |              ^
   arch/arm64/kvm/sys_regs.c:2200:49: note: in expansion of macro 'NULL'
    2200 |           .access = access_pmu_evcntr, .reset = NULL },
         |                                                 ^~~~
   include/linux/stddef.h:8:14: note: (near initialization for 'sys_reg_descs[243].reset')
       8 | #define NULL ((void *)0)
         |              ^
   arch/arm64/kvm/sys_regs.c:2200:49: note: in expansion of macro 'NULL'
    2200 |           .access = access_pmu_evcntr, .reset = NULL },
         |                                                 ^~~~
   arch/arm64/kvm/sys_regs.c:2206:20: warning: initialized field overwritten [-Woverride-init]
    2206 |           .reset = reset_val, .reg = PMUSERENR_EL0, .val = 0 },
         |                    ^~~~~~~~~
   arch/arm64/kvm/sys_regs.c:2206:20: note: (near initialization for 'sys_reg_descs[244].reset')
   arch/arm64/kvm/sys_regs.c:1128:20: warning: initialized field overwritten [-Woverride-init]
    1128 |           .reset = reset_pmevcntr, .get_user = get_pmu_evcntr,          \
         |                    ^~~~~~~~~~~~~~
   arch/arm64/kvm/sys_regs.c:2296:9: note: in expansion of macro 'PMU_PMEVCNTR_EL0'
    2296 |         PMU_PMEVCNTR_EL0(0),


vim +/kvm_pmu_evtyper_mask +754 arch/arm64/kvm/sys_regs.c

   746	
   747	static u64 reset_pmevtyper(struct kvm_vcpu *vcpu, const struct sys_reg_desc *r)
   748	{
   749		/* This thing will UNDEF, who cares about the reset value? */
   750		if (!kvm_vcpu_has_pmu(vcpu))
   751			return 0;
   752	
   753		reset_unknown(vcpu, r);
 > 754		__vcpu_sys_reg(vcpu, r->reg) &= kvm_pmu_evtyper_mask(vcpu->kvm);
   755	
   756		return __vcpu_sys_reg(vcpu, r->reg);
   757	}
   758
Oliver Upton Oct. 24, 2023, 6:58 p.m. UTC | #2 
On Tue, Oct 24, 2023 at 10:47:58AM +0800, kernel test robot wrote:
> Hi Oliver,
> 
> kernel test robot noticed the following build errors:
> 
> [auto build test ERROR on 6465e260f48790807eef06b583b38ca9789b6072]
> 
> url:    https://github.com/intel-lab-lkp/linux/commits/Oliver-Upton/KVM-arm64-Make-PMEVTYPER-n-_EL0-NSH-RES0-if-EL2-isn-t-advertised/20231020-025836
> base:   6465e260f48790807eef06b583b38ca9789b6072
> patch link:    https://lore.kernel.org/r/20231019185618.3442949-2-oliver.upton%40linux.dev
> patch subject: [PATCH v3 1/2] KVM: arm64: Make PMEVTYPER<n>_EL0.NSH RES0 if EL2 isn't advertised
> config: arm64-randconfig-004-20231023 (https://download.01.org/0day-ci/archive/20231024/202310241025.FmLnpSTG-lkp@intel.com/config)
> compiler: aarch64-linux-gcc (GCC) 13.2.0
> reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20231024/202310241025.FmLnpSTG-lkp@intel.com/reproduce)
> 
> If you fix the issue in a separate patch/commit (i.e. not just a new version of
> the same patch/commit), kindly add following tags
> | Reported-by: kernel test robot <lkp@intel.com>
> | Closes: https://lore.kernel.org/oe-kbuild-all/202310241025.FmLnpSTG-lkp@intel.com/
> 
> All errors (new ones prefixed by >>):
> 
>    arch/arm64/kvm/sys_regs.c: In function 'reset_pmevtyper':
> >> arch/arm64/kvm/sys_regs.c:754:41: error: too many arguments to function 'kvm_pmu_evtyper_mask'

Ah, the prototype for !CONFIG_HW_PERF_EVENTS is wrong. I'll squash this
in:

diff --git a/include/kvm/arm_pmu.h b/include/kvm/arm_pmu.h
index e0bcf447a2ab..fd0aa8105a5b 100644
--- a/include/kvm/arm_pmu.h
+++ b/include/kvm/arm_pmu.h
@@ -173,7 +173,7 @@ static inline u8 kvm_arm_pmu_get_pmuver_limit(void)
 {
 	return 0;
 }
-static inline u64 kvm_pmu_evtyper_mask(void)
+static inline u64 kvm_pmu_evtyper_mask(struct kvm *kvm)
 {
 	return 0;
 }
diff mbox series

Patch

diff --git a/arch/arm64/kvm/pmu-emul.c b/arch/arm64/kvm/pmu-emul.c
index 6b066e04dc5d..32d83db9674e 100644
--- a/arch/arm64/kvm/pmu-emul.c
+++ b/arch/arm64/kvm/pmu-emul.c
@@ -60,6 +60,18 @@  static u32 kvm_pmu_event_mask(struct kvm *kvm)
 	return __kvm_pmu_event_mask(pmuver);
 }
 
+u64 kvm_pmu_evtyper_mask(struct kvm *kvm)
+{
+	u64 mask = ARMV8_PMU_EXCLUDE_EL1 | ARMV8_PMU_EXCLUDE_EL0 |
+		   kvm_pmu_event_mask(kvm);
+	u64 pfr0 = IDREG(kvm, SYS_ID_AA64PFR0_EL1);
+
+	if (SYS_FIELD_GET(ID_AA64PFR0_EL1, EL2, pfr0))
+		mask |= ARMV8_PMU_INCLUDE_EL2;
+
+	return mask;
+}
+
 /**
  * kvm_pmc_is_64bit - determine if counter is 64bit
  * @pmc: counter context
@@ -657,18 +669,13 @@  void kvm_pmu_set_counter_event_type(struct kvm_vcpu *vcpu, u64 data,
 				    u64 select_idx)
 {
 	struct kvm_pmc *pmc = kvm_vcpu_idx_to_pmc(vcpu, select_idx);
-	u64 reg, mask;
+	u64 reg;
 
 	if (!kvm_vcpu_has_pmu(vcpu))
 		return;
 
-	mask  =  ARMV8_PMU_EVTYPE_MASK;
-	mask &= ~ARMV8_PMU_EVTYPE_EVENT;
-	mask |= kvm_pmu_event_mask(vcpu->kvm);
-
 	reg = counter_index_to_evtreg(pmc->idx);
-
-	__vcpu_sys_reg(vcpu, reg) = data & mask;
+	__vcpu_sys_reg(vcpu, reg) = data & kvm_pmu_evtyper_mask(vcpu->kvm);
 
 	kvm_pmu_create_perf_event(pmc);
 }
diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index e92ec810d449..78720c373904 100644
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c
@@ -746,8 +746,12 @@  static u64 reset_pmevcntr(struct kvm_vcpu *vcpu, const struct sys_reg_desc *r)
 
 static u64 reset_pmevtyper(struct kvm_vcpu *vcpu, const struct sys_reg_desc *r)
 {
+	/* This thing will UNDEF, who cares about the reset value? */
+	if (!kvm_vcpu_has_pmu(vcpu))
+		return 0;
+
 	reset_unknown(vcpu, r);
-	__vcpu_sys_reg(vcpu, r->reg) &= ARMV8_PMU_EVTYPE_MASK;
+	__vcpu_sys_reg(vcpu, r->reg) &= kvm_pmu_evtyper_mask(vcpu->kvm);
 
 	return __vcpu_sys_reg(vcpu, r->reg);
 }
@@ -988,7 +992,7 @@  static bool access_pmu_evtyper(struct kvm_vcpu *vcpu, struct sys_reg_params *p,
 		kvm_pmu_set_counter_event_type(vcpu, p->regval, idx);
 		kvm_vcpu_pmu_restore_guest(vcpu);
 	} else {
-		p->regval = __vcpu_sys_reg(vcpu, reg) & ARMV8_PMU_EVTYPE_MASK;
+		p->regval = __vcpu_sys_reg(vcpu, reg);
 	}
 
 	return true;
diff --git a/include/kvm/arm_pmu.h b/include/kvm/arm_pmu.h
index 31029f4f7be8..e0bcf447a2ab 100644
--- a/include/kvm/arm_pmu.h
+++ b/include/kvm/arm_pmu.h
@@ -101,6 +101,7 @@  void kvm_vcpu_pmu_resync_el0(void);
 })
 
 u8 kvm_arm_pmu_get_pmuver_limit(void);
+u64 kvm_pmu_evtyper_mask(struct kvm *kvm);
 
 #else
 struct kvm_pmu {
@@ -172,6 +173,10 @@  static inline u8 kvm_arm_pmu_get_pmuver_limit(void)
 {
 	return 0;
 }
+static inline u64 kvm_pmu_evtyper_mask(void)
+{
+	return 0;
+}
 static inline void kvm_vcpu_pmu_resync_el0(void) {}
 
 #endif