KVM ARM Archive on lore.kernel.org
 help / color / Atom feed
From: Marc Zyngier <maz@kernel.org>
To: qemu-devel@nongnu.org
Cc: "Edgar E. Iglesias" <edgar.iglesias@xilinx.com>,
	Richard Henderson <richard.henderson@linaro.org>,
	kvmarm@lists.cs.columbia.edu
Subject: [PATCH v2 4/5] target/arm: Handle AArch32 CP15 trapping via HSTR_EL2
Date: Sun,  1 Dec 2019 12:20:17 +0000
Message-ID: <20191201122018.25808-5-maz@kernel.org> (raw)
In-Reply-To: <20191201122018.25808-1-maz@kernel.org>

HSTR_EL2 offers a way to trap ranges of CP15 system register
accesses to EL2, and it looks like this register is completely
ignored by QEMU.

To avoid adding extra .accessfn filters all over the place (which
would have a direct performance impact), let's add a new TB flag
that gets set whenever HSTR_EL2 is non-zero and that QEMU translates
a context where this trap has a chance to apply, and only generate
the extra access check if the hypervisor is actively using this feature.

Tested with a hand-crafted KVM guest accessing CBAR.

Signed-off-by: Marc Zyngier <maz@kernel.org>
---
 target/arm/cpu.h       |  2 ++
 target/arm/helper.c    |  6 ++++++
 target/arm/op_helper.c | 21 +++++++++++++++++++++
 target/arm/translate.c |  3 ++-
 target/arm/translate.h |  2 ++
 5 files changed, 33 insertions(+), 1 deletion(-)

diff --git a/target/arm/cpu.h b/target/arm/cpu.h
index 83a809d4ba..cebb3511a5 100644
--- a/target/arm/cpu.h
+++ b/target/arm/cpu.h
@@ -3215,6 +3215,8 @@ FIELD(TBFLAG_A32, NS, 6, 1)
 FIELD(TBFLAG_A32, VFPEN, 7, 1)          /* Partially cached, minus FPEXC. */
 FIELD(TBFLAG_A32, CONDEXEC, 8, 8)       /* Not cached. */
 FIELD(TBFLAG_A32, SCTLR_B, 16, 1)
+FIELD(TBFLAG_A32, HSTR_ACTIVE, 17, 1)
+
 /* For M profile only, set if FPCCR.LSPACT is set */
 FIELD(TBFLAG_A32, LSPACT, 18, 1)        /* Not cached. */
 /* For M profile only, set if we must create a new FP context */
diff --git a/target/arm/helper.c b/target/arm/helper.c
index 93ecab27c0..0ba08d550a 100644
--- a/target/arm/helper.c
+++ b/target/arm/helper.c
@@ -11283,6 +11283,12 @@ static uint32_t rebuild_hflags_a32(CPUARMState *env, int fp_el,
     if (arm_el_is_aa64(env, 1)) {
         flags = FIELD_DP32(flags, TBFLAG_A32, VFPEN, 1);
     }
+
+    if (arm_current_el(env) < 2 && env->cp15.hstr_el2 &&
+        (arm_hcr_el2_eff(env) & (HCR_E2H | HCR_TGE)) != (HCR_E2H | HCR_TGE)) {
+        flags = FIELD_DP32(flags, TBFLAG_A32, HSTR_ACTIVE, 1);
+    }
+
     return rebuild_hflags_common_32(env, fp_el, mmu_idx, flags);
 }
 
diff --git a/target/arm/op_helper.c b/target/arm/op_helper.c
index b529d6c1bf..681c5f3681 100644
--- a/target/arm/op_helper.c
+++ b/target/arm/op_helper.c
@@ -603,6 +603,26 @@ void HELPER(access_check_cp_reg)(CPUARMState *env, void *rip, uint32_t syndrome,
         raise_exception(env, EXCP_UDEF, syndrome, exception_target_el(env));
     }
 
+    /* Check for an EL2 trap due to HSTR_EL2. We expect EL0 accesses
+     * to sysregs non accessible at EL0 to have UNDEF-ed already.
+     */
+    if (!env->aarch64 && arm_current_el(env) < 2 && ri->cp == 15 &&
+        (arm_hcr_el2_eff(env) & (HCR_E2H | HCR_TGE)) != (HCR_E2H | HCR_TGE)) {
+        uint32_t mask = 1 << ri->crn;
+
+        if (ri->type & ARM_CP_64BIT) {
+            mask = 1 << ri->crm;
+        }
+
+        /* T4 and T14 are RES0 */
+        mask &= ~((1 << 4) | (1 << 14));
+
+        if (env->cp15.hstr_el2 & mask) {
+            target_el = 2;
+            goto exept;
+        }
+    }
+
     if (!ri->accessfn) {
         return;
     }
@@ -652,6 +672,7 @@ void HELPER(access_check_cp_reg)(CPUARMState *env, void *rip, uint32_t syndrome,
         g_assert_not_reached();
     }
 
+exept:
     raise_exception(env, EXCP_UDEF, syndrome, target_el);
 }
 
diff --git a/target/arm/translate.c b/target/arm/translate.c
index 4d5d4bd888..f162be8434 100644
--- a/target/arm/translate.c
+++ b/target/arm/translate.c
@@ -6897,7 +6897,7 @@ static int disas_coproc_insn(DisasContext *s, uint32_t insn)
             return 1;
         }
 
-        if (ri->accessfn ||
+        if (s->hstr_active || ri->accessfn ||
             (arm_dc_feature(s, ARM_FEATURE_XSCALE) && cpnum < 14)) {
             /* Emit code to perform further access permissions checks at
              * runtime; this may result in an exception.
@@ -10843,6 +10843,7 @@ static void arm_tr_init_disas_context(DisasContextBase *dcbase, CPUState *cs)
                                !arm_el_is_aa64(env, 3);
     dc->thumb = FIELD_EX32(tb_flags, TBFLAG_A32, THUMB);
     dc->sctlr_b = FIELD_EX32(tb_flags, TBFLAG_A32, SCTLR_B);
+    dc->hstr_active = FIELD_EX32(tb_flags, TBFLAG_A32, HSTR_ACTIVE);
     dc->be_data = FIELD_EX32(tb_flags, TBFLAG_ANY, BE_DATA) ? MO_BE : MO_LE;
     condexec = FIELD_EX32(tb_flags, TBFLAG_A32, CONDEXEC);
     dc->condexec_mask = (condexec & 0xf) << 1;
diff --git a/target/arm/translate.h b/target/arm/translate.h
index dd24f91f26..b837b7fcbf 100644
--- a/target/arm/translate.h
+++ b/target/arm/translate.h
@@ -77,6 +77,8 @@ typedef struct DisasContext {
     bool pauth_active;
     /* True with v8.5-BTI and SCTLR_ELx.BT* set.  */
     bool bt;
+    /* True if any CP15 access is trapped by HSTR_EL2 */
+    bool hstr_active;
     /*
      * >= 0, a copy of PSTATE.BTYPE, which will be 0 without v8.5-BTI.
      *  < 0, set by the current instruction.
-- 
2.20.1

_______________________________________________
kvmarm mailing list
kvmarm@lists.cs.columbia.edu
https://lists.cs.columbia.edu/mailman/listinfo/kvmarm

  parent reply index

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-12-01 12:20 [PATCH v2 0/5] target/arm: More EL2 trapping fixes Marc Zyngier
2019-12-01 12:20 ` [PATCH v2 1/5] target/arm: Honor HCR_EL2.TID2 trapping requirements Marc Zyngier
2019-12-02 13:52   ` Edgar E. Iglesias
2019-12-02 15:10   ` Richard Henderson
2019-12-01 12:20 ` [PATCH v2 2/5] target/arm: Honor HCR_EL2.TID1 " Marc Zyngier
2019-12-02 15:22   ` Richard Henderson
2019-12-01 12:20 ` [PATCH v2 3/5] target/arm: Handle trapping to EL2 of AArch32 VMRS instructions Marc Zyngier
2019-12-02 15:35   ` Richard Henderson
2019-12-02 16:45     ` Marc Zyngier
2019-12-02 16:56       ` Richard Henderson
2019-12-02 17:15         ` Marc Zyngier
2019-12-06 14:08   ` Peter Maydell
2019-12-06 14:14     ` Marc Zyngier
2019-12-06 17:45     ` Richard Henderson
2019-12-01 12:20 ` Marc Zyngier [this message]
2019-12-02 15:52   ` [PATCH v2 4/5] target/arm: Handle AArch32 CP15 trapping via HSTR_EL2 Richard Henderson
2019-12-01 12:20 ` [PATCH v2 5/5] target/arm: Add support for missing Jazelle system registers Marc Zyngier
2019-12-02 14:07   ` Edgar E. Iglesias
2019-12-02 15:57   ` Richard Henderson
2019-12-06 13:56     ` Peter Maydell
2019-12-06 14:13 ` [PATCH v2 0/5] target/arm: More EL2 trapping fixes Peter Maydell
2019-12-06 14:19   ` Marc Zyngier

Reply instructions:

You may reply publically to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20191201122018.25808-5-maz@kernel.org \
    --to=maz@kernel.org \
    --cc=edgar.iglesias@xilinx.com \
    --cc=kvmarm@lists.cs.columbia.edu \
    --cc=qemu-devel@nongnu.org \
    --cc=richard.henderson@linaro.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

KVM ARM Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/kvmarm/0 kvmarm/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 kvmarm kvmarm/ https://lore.kernel.org/kvmarm \
		kvmarm@lists.cs.columbia.edu
	public-inbox-index kvmarm

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/edu.columbia.cs.lists.kvmarm


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git