exec: [tcg] Use different TBs according to the vCPU's dynamic tracing state

Every vCPU now uses a separate set of TBs for each set of dynamic
tracing event state values. Each set of TBs can be used by any number of
vCPUs to maximize TB reuse when vCPUs have the same tracing state.

This feature is later used by tracetool to optimize tracing of guest
code events.

The maximum number of TB sets is defined as 2^E, where E is the number
of events that have the 'vcpu' property (their state is stored in
CPUState->trace_dstate).

For this to work, a change on the dynamic tracing state of a vCPU will
force it to flush its virtual TB cache (which is only indexed by
address), and fall back to the physical TB cache (which now contains the
vCPU's dynamic tracing state as part of the hashing function).

Signed-off-by: Lluís Vilanova <vilanova@ac.upc.edu>
Reviewed-by: Richard Henderson <rth@twiddle.net>
Reviewed-by: Emilio G. Cota <cota@braap.org>
Signed-off-by: Emilio G. Cota <cota@braap.org>
Message-id: 149915775266.6295.10060144081246467690.stgit@frigg.lan
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

1 files changed, 2 insertions, 1 deletions

diff --git a/tcg/tcg-runtime.c b/tcg/tcg-runtime.c
index ec3a34e461..3e23649dd7 100644
--- a/tcg/tcg-runtime.c
+++ b/tcg/tcg-runtime.c
@@ -158,7 +158,8 @@ void *HELPER(lookup_tb_ptr)(CPUArchState *env, target_ulong addr)
     if (unlikely(!(tb
                    && tb->pc == addr
                    && tb->cs_base == cs_base
-                   && tb->flags == flags))) {
+                   && tb->flags == flags
+                   && tb->trace_vcpu_dstate == *cpu->trace_dstate))) {
         tb = tb_htable_lookup(cpu, addr, cs_base, flags);
         if (!tb) {
             return tcg_ctx.code_gen_epilogue;