[PULL 06/20] accel/tcg: Suppress auto-invalidate in probe_access_internal

Richard Henderson posted 20 patches 2 years, 6 months ago
Maintainers: Richard Henderson <richard.henderson@linaro.org>, Paolo Bonzini <pbonzini@redhat.com>, Eduardo Habkost <eduardo@habkost.net>, Marcel Apfelbaum <marcel.apfelbaum@gmail.com>, "Philippe Mathieu-Daudé" <f4bug@amsat.org>, Yanan Wang <wangyanan55@huawei.com>, Laurent Vivier <laurent@vivier.eu>, "Alex Bennée" <alex.bennee@linaro.org>, Alexandre Iooss <erdnaxe@crans.org>, Mahmoud Mandour <ma.mandourr@gmail.com>, Peter Maydell <peter.maydell@linaro.org>, Michael Rolnik <mrolnik@gmail.com>, "Edgar E. Iglesias" <edgar.iglesias@gmail.com>, Taylor Simpson <tsimpson@quicinc.com>, Song Gao <gaosong@loongson.cn>, Xiaojuan Yang <yangxiaojuan@loongson.cn>, Aurelien Jarno <aurelien@aurel32.net>, Jiaxun Yang <jiaxun.yang@flygoat.com>, Aleksandar Rikalo <aleksandar.rikalo@syrmia.com>, Chris Wulff <crwulff@gmail.com>, Marek Vasut <marex@denx.de>, Stafford Horne <shorne@gmail.com>, "Cédric Le Goater" <clg@kaod.org>, Daniel Henrique Barboza <danielhb413@gmail.com>, David Gibson <david@gibson.dropbear.id.au>, Greg Kurz <groug@kaod.org>, Palmer Dabbelt <palmer@dabbelt.com>, Alistair Francis <alistair.francis@wdc.com>, Bin Meng <bin.meng@windriver.com>, Yoshinori Sato <ysato@users.sourceforge.jp>, David Hildenbrand <david@redhat.com>, Cornelia Huck <cohuck@redhat.com>, Thomas Huth <thuth@redhat.com>, Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>, Artyom Tarasenko <atar4qemu@gmail.com>, Bastian Koppelmann <kbastian@mail.uni-paderborn.de>, Max Filippov <jcmvbkbc@gmail.com>, Stefan Hajnoczi <stefanha@redhat.com>
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[PULL 06/20] accel/tcg: Suppress auto-invalidate in probe_access_internal
Posted by Richard Henderson 2 years, 6 months ago
When PAGE_WRITE_INV is set when calling tlb_set_page,
we immediately set TLB_INVALID_MASK in order to force
tlb_fill to be called on the next lookup.  Here in
probe_access_internal, we have just called tlb_fill
and eliminated true misses, thus the lookup must be valid.

This allows us to remove a warning comment from s390x.
There doesn't seem to be a reason to change the code though.

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
 accel/tcg/cputlb.c            | 10 +++++++++-
 target/s390x/tcg/mem_helper.c |  4 ----
 2 files changed, 9 insertions(+), 5 deletions(-)

diff --git a/accel/tcg/cputlb.c b/accel/tcg/cputlb.c
index d06ff44ce9..264f84a248 100644
--- a/accel/tcg/cputlb.c
+++ b/accel/tcg/cputlb.c
@@ -1533,6 +1533,7 @@ static int probe_access_internal(CPUArchState *env, target_ulong addr,
     }
     tlb_addr = tlb_read_ofs(entry, elt_ofs);
 
+    flags = TLB_FLAGS_MASK;
     page_addr = addr & TARGET_PAGE_MASK;
     if (!tlb_hit_page(tlb_addr, page_addr)) {
         if (!victim_tlb_hit(env, mmu_idx, index, elt_ofs, page_addr)) {
@@ -1547,10 +1548,17 @@ static int probe_access_internal(CPUArchState *env, target_ulong addr,
 
             /* TLB resize via tlb_fill may have moved the entry.  */
             entry = tlb_entry(env, mmu_idx, addr);
+
+            /*
+             * With PAGE_WRITE_INV, we set TLB_INVALID_MASK immediately,
+             * to force the next access through tlb_fill.  We've just
+             * called tlb_fill, so we know that this entry *is* valid.
+             */
+            flags &= ~TLB_INVALID_MASK;
         }
         tlb_addr = tlb_read_ofs(entry, elt_ofs);
     }
-    flags = tlb_addr & TLB_FLAGS_MASK;
+    flags &= tlb_addr;
 
     /* Fold all "mmio-like" bits into TLB_MMIO.  This is not RAM.  */
     if (unlikely(flags & ~(TLB_WATCHPOINT | TLB_NOTDIRTY))) {
diff --git a/target/s390x/tcg/mem_helper.c b/target/s390x/tcg/mem_helper.c
index fc52aa128b..3758b9e688 100644
--- a/target/s390x/tcg/mem_helper.c
+++ b/target/s390x/tcg/mem_helper.c
@@ -148,10 +148,6 @@ static int s390_probe_access(CPUArchState *env, target_ulong addr, int size,
 #else
     int flags;
 
-    /*
-     * For !CONFIG_USER_ONLY, we cannot rely on TLB_INVALID_MASK or haddr==NULL
-     * to detect if there was an exception during tlb_fill().
-     */
     env->tlb_fill_exc = 0;
     flags = probe_access_flags(env, addr, access_type, mmu_idx, nonfault, phost,
                                ra);
-- 
2.34.1