KVM: arm64: Sanely ratelimit sysreg messages

Currently kvm_pr_unimpl() is ratelimited, so print_sys_reg_instr() won't
spam the console. However, someof its callers try to print some
contextual information with kvm_err(), which is not ratelimited. This
means that in some cases the context may be printed without the sysreg
encoding, which isn't all that useful.

Let's ensure that both are consistently printed together and
ratelimited, by refactoring print_sys_reg_instr() so that some callers
can provide it with an arbitrary format string.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20191205180652.18671-2-mark.rutland@arm.com

diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index 2071260a275bd236923da5650da86a012eaa5b4a..e8bf08e09f78370896d5576df3269661d0e4caa8 100644 (file)
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c
@@ -2094,9 +2094,9 @@ static void unhandled_cp_access(struct kvm_vcpu *vcpu,
                WARN_ON(1);
        }
 
-       kvm_err("Unsupported guest CP%d access at: %08lx [%08lx]\n",
-               cp, *vcpu_pc(vcpu), *vcpu_cpsr(vcpu));
-       print_sys_reg_instr(params);
+       print_sys_reg_msg(params,
+                         "Unsupported guest CP%d access at: %08lx [%08lx]\n",
+                         cp, *vcpu_pc(vcpu), *vcpu_cpsr(vcpu));
        kvm_inject_undefined(vcpu);
 }
 
@@ -2245,9 +2245,9 @@ static int emulate_sys_reg(struct kvm_vcpu *vcpu,
        if (likely(r)) {
                perform_access(vcpu, params, r);
        } else {
-               kvm_err("Unsupported guest sys_reg access at: %lx [%08lx]\n",
-                       *vcpu_pc(vcpu), *vcpu_cpsr(vcpu));
-               print_sys_reg_instr(params);
+               print_sys_reg_msg(params,
+                                 "Unsupported guest sys_reg access at: %lx [%08lx]\n",
+                                 *vcpu_pc(vcpu), *vcpu_cpsr(vcpu));
                kvm_inject_undefined(vcpu);
        }
        return 1;

diff --git a/arch/arm64/kvm/sys_regs.h b/arch/arm64/kvm/sys_regs.h
index 9bca0312d7982c4d1a8620ef907ea683abd6c598..5a6fc30f59894db482b667c20dd892baba0e6c7f 100644 (file)
--- a/arch/arm64/kvm/sys_regs.h
+++ b/arch/arm64/kvm/sys_regs.h
@@ -62,11 +62,24 @@ struct sys_reg_desc {
 #define REG_HIDDEN_USER                (1 << 0) /* hidden from userspace ioctls */
 #define REG_HIDDEN_GUEST       (1 << 1) /* hidden from guest */
 
-static inline void print_sys_reg_instr(const struct sys_reg_params *p)
+static __printf(2, 3)
+inline void print_sys_reg_msg(const struct sys_reg_params *p,
+                                      char *fmt, ...)
 {
+       va_list va;
+
+       va_start(va, fmt);
        /* Look, we even formatted it for you to paste into the table! */
-       kvm_pr_unimpl(" { Op0(%2u), Op1(%2u), CRn(%2u), CRm(%2u), Op2(%2u), func_%s },\n",
+       kvm_pr_unimpl("%pV { Op0(%2u), Op1(%2u), CRn(%2u), CRm(%2u), Op2(%2u), func_%s },\n",
+                     &(struct va_format){ fmt, &va },
                      p->Op0, p->Op1, p->CRn, p->CRm, p->Op2, p->is_write ? "write" : "read");
+       va_end(va);
+}
+
+static inline void print_sys_reg_instr(const struct sys_reg_params *p)
+{
+       /* GCC warns on an empty format string */
+       print_sys_reg_msg(p, "%s", "");
 }
 
 static inline bool ignore_write(struct kvm_vcpu *vcpu,