[PATCH v3 0/4] target/arm: Reduce aa64_va_parameter overhead

[PATCH v3 0/4] target/arm: Reduce aa64_va_parameter overhead

[Richard Henderson]

Something I noticed while developing and testing VHE.

For v2, fix select as a separate patch.
For v3, adjust pauth to use bit 55 explicitly, and remove a
now duplicate test within get_phys_addr_lpae.


r~


Richard Henderson (4):
  target/arm: Use bit 55 explicitly for pauth
  target/arm: Fix select for aa64_va_parameters_both
  target/arm: Remove ttbr1_valid check from get_phys_addr_lpae
  target/arm: Split out aa64_va_parameter_tbi, aa64_va_parameter_tbid

 target/arm/internals.h    |   3 -
 target/arm/helper.c       | 144 ++++++++++++++++++++------------------
 target/arm/pauth_helper.c |   3 +-
 3 files changed, 76 insertions(+), 74 deletions(-)

-- 
2.20.1

[PATCH v3 1/4] target/arm: Use bit 55 explicitly for pauth

[Richard Henderson]

The psuedocode in aarch64/functions/pac/auth/Auth and
aarch64/functions/pac/strip/Strip always uses bit 55 for
extfield and do not consider if the current regime has 2 ranges.

Suggested-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
 target/arm/pauth_helper.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/target/arm/pauth_helper.c b/target/arm/pauth_helper.c
index 9746e32bf8..b909630317 100644
--- a/target/arm/pauth_helper.c
+++ b/target/arm/pauth_helper.c
@@ -320,7 +320,8 @@ static uint64_t pauth_addpac(CPUARMState *env, uint64_t ptr, uint64_t modifier,
 
 static uint64_t pauth_original_ptr(uint64_t ptr, ARMVAParameters param)
 {
-    uint64_t extfield = -param.select;
+    /* Note that bit 55 is used whether or not the regime has 2 ranges. */
+    uint64_t extfield = sextract64(ptr, 55, 1);
     int bot_pac_bit = 64 - param.tsz;
     int top_pac_bit = 64 - 8 * param.tbi;
 
-- 
2.20.1

Re: [PATCH v3 1/4] target/arm: Use bit 55 explicitly for pauth

[Peter Maydell]

On Sun, 16 Feb 2020 at 19:43, Richard Henderson
<richard.henderson@linaro.org> wrote:
>
> The psuedocode in aarch64/functions/pac/auth/Auth and
> aarch64/functions/pac/strip/Strip always uses bit 55 for
> extfield and do not consider if the current regime has 2 ranges.
>
> Suggested-by: Peter Maydell <peter.maydell@linaro.org>
> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
> ---
>  target/arm/pauth_helper.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>

('pseudocode', but I'll fix the typo when I apply it if
it doesn't need a respin for some other reason)

thanks
-- PMM

[PATCH v3 2/4] target/arm: Fix select for aa64_va_parameters_both

[Richard Henderson]

Select should always be 0 for a regime with one range.

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
 target/arm/helper.c | 46 +++++++++++++++++++++++----------------------
 1 file changed, 24 insertions(+), 22 deletions(-)

diff --git a/target/arm/helper.c b/target/arm/helper.c
index 366dbcf460..b09a501284 100644
--- a/target/arm/helper.c
+++ b/target/arm/helper.c
@@ -10241,13 +10241,8 @@ ARMVAParameters aa64_va_parameters_both(CPUARMState *env, uint64_t va,
     bool tbi, tbid, epd, hpd, using16k, using64k;
     int select, tsz;
 
-    /*
-     * Bit 55 is always between the two regions, and is canonical for
-     * determining if address tagging is enabled.
-     */
-    select = extract64(va, 55, 1);
-
     if (!regime_has_2_ranges(mmu_idx)) {
+        select = 0;
         tsz = extract32(tcr, 0, 6);
         using64k = extract32(tcr, 14, 1);
         using16k = extract32(tcr, 15, 1);
@@ -10260,23 +10255,30 @@ ARMVAParameters aa64_va_parameters_both(CPUARMState *env, uint64_t va,
             tbid = extract32(tcr, 29, 1);
         }
         epd = false;
-    } else if (!select) {
-        tsz = extract32(tcr, 0, 6);
-        epd = extract32(tcr, 7, 1);
-        using64k = extract32(tcr, 14, 1);
-        using16k = extract32(tcr, 15, 1);
-        tbi = extract64(tcr, 37, 1);
-        hpd = extract64(tcr, 41, 1);
-        tbid = extract64(tcr, 51, 1);
     } else {
-        int tg = extract32(tcr, 30, 2);
-        using16k = tg == 1;
-        using64k = tg == 3;
-        tsz = extract32(tcr, 16, 6);
-        epd = extract32(tcr, 23, 1);
-        tbi = extract64(tcr, 38, 1);
-        hpd = extract64(tcr, 42, 1);
-        tbid = extract64(tcr, 52, 1);
+        /*
+         * Bit 55 is always between the two regions, and is canonical for
+         * determining if address tagging is enabled.
+         */
+        select = extract64(va, 55, 1);
+        if (!select) {
+            tsz = extract32(tcr, 0, 6);
+            epd = extract32(tcr, 7, 1);
+            using64k = extract32(tcr, 14, 1);
+            using16k = extract32(tcr, 15, 1);
+            tbi = extract64(tcr, 37, 1);
+            hpd = extract64(tcr, 41, 1);
+            tbid = extract64(tcr, 51, 1);
+        } else {
+            int tg = extract32(tcr, 30, 2);
+            using16k = tg == 1;
+            using64k = tg == 3;
+            tsz = extract32(tcr, 16, 6);
+            epd = extract32(tcr, 23, 1);
+            tbi = extract64(tcr, 38, 1);
+            hpd = extract64(tcr, 42, 1);
+            tbid = extract64(tcr, 52, 1);
+        }
     }
     tsz = MIN(tsz, 39);  /* TODO: ARMv8.4-TTST */
     tsz = MAX(tsz, 16);  /* TODO: ARMv8.2-LVA  */
-- 
2.20.1

[PATCH v3 3/4] target/arm: Remove ttbr1_valid check from get_phys_addr_lpae

[Richard Henderson]

Now that aa64_va_parameters_both sets select based on the number
of ranges in the regime, the ttbr1_valid check is redundant.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
 target/arm/helper.c | 6 +-----
 1 file changed, 1 insertion(+), 5 deletions(-)

diff --git a/target/arm/helper.c b/target/arm/helper.c
index b09a501284..eec7b01ab3 100644
--- a/target/arm/helper.c
+++ b/target/arm/helper.c
@@ -10390,7 +10390,6 @@ static bool get_phys_addr_lpae(CPUARMState *env, target_ulong address,
     TCR *tcr = regime_tcr(env, mmu_idx);
     int ap, ns, xn, pxn;
     uint32_t el = regime_el(env, mmu_idx);
-    bool ttbr1_valid;
     uint64_t descaddrmask;
     bool aarch64 = arm_el_is_aa64(env, el);
     bool guarded = false;
@@ -10405,14 +10404,11 @@ static bool get_phys_addr_lpae(CPUARMState *env, target_ulong address,
         param = aa64_va_parameters(env, address, mmu_idx,
                                    access_type != MMU_INST_FETCH);
         level = 0;
-        ttbr1_valid = regime_has_2_ranges(mmu_idx);
         addrsize = 64 - 8 * param.tbi;
         inputsize = 64 - param.tsz;
     } else {
         param = aa32_va_parameters(env, address, mmu_idx);
         level = 1;
-        /* There is no TTBR1 for EL2 */
-        ttbr1_valid = (el != 2);
         addrsize = (mmu_idx == ARMMMUIdx_Stage2 ? 40 : 32);
         inputsize = addrsize - param.tsz;
     }
@@ -10429,7 +10425,7 @@ static bool get_phys_addr_lpae(CPUARMState *env, target_ulong address,
     if (inputsize < addrsize) {
         target_ulong top_bits = sextract64(address, inputsize,
                                            addrsize - inputsize);
-        if (-top_bits != param.select || (param.select && !ttbr1_valid)) {
+        if (-top_bits != param.select) {
             /* The gap between the two regions is a Translation fault */
             fault_type = ARMFault_Translation;
             goto do_fault;
-- 
2.20.1

[PATCH v3 4/4] target/arm: Split out aa64_va_parameter_tbi, aa64_va_parameter_tbid

[Richard Henderson]

For the purpose of rebuild_hflags_a64, we do not need to compute
all of the va parameters, only tbi.  Moreover, we can compute them
in a form that is more useful to storing in hflags.

This eliminates the need for aa64_va_parameter_both, so fold that
in to aa64_va_parameter.  The remaining calls to aa64_va_parameter
are in get_phys_addr_lpae and in pauth_helper.c.

This reduces the total cpu consumption of aa64_va_parameter in a
kernel boot plus a kvm guest kernel boot from 3% to 0.5%.

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
 target/arm/internals.h |  3 --
 target/arm/helper.c    | 68 +++++++++++++++++++++++-------------------
 2 files changed, 37 insertions(+), 34 deletions(-)

diff --git a/target/arm/internals.h b/target/arm/internals.h
index 58c4d707c5..14328e3f7d 100644
--- a/target/arm/internals.h
+++ b/target/arm/internals.h
@@ -1127,15 +1127,12 @@ typedef struct ARMVAParameters {
     unsigned tsz    : 8;
     unsigned select : 1;
     bool tbi        : 1;
-    bool tbid       : 1;
     bool epd        : 1;
     bool hpd        : 1;
     bool using16k   : 1;
     bool using64k   : 1;
 } ARMVAParameters;
 
-ARMVAParameters aa64_va_parameters_both(CPUARMState *env, uint64_t va,
-                                        ARMMMUIdx mmu_idx);
 ARMVAParameters aa64_va_parameters(CPUARMState *env, uint64_t va,
                                    ARMMMUIdx mmu_idx, bool data);
 
diff --git a/target/arm/helper.c b/target/arm/helper.c
index eec7b01ab3..8d0f6eca27 100644
--- a/target/arm/helper.c
+++ b/target/arm/helper.c
@@ -10234,12 +10234,34 @@ static uint8_t convert_stage2_attrs(CPUARMState *env, uint8_t s2attrs)
 }
 #endif /* !CONFIG_USER_ONLY */
 
-ARMVAParameters aa64_va_parameters_both(CPUARMState *env, uint64_t va,
-                                        ARMMMUIdx mmu_idx)
+static int aa64_va_parameter_tbi(uint64_t tcr, ARMMMUIdx mmu_idx)
+{
+    if (regime_has_2_ranges(mmu_idx)) {
+        return extract64(tcr, 37, 2);
+    } else if (mmu_idx == ARMMMUIdx_Stage2) {
+        return 0; /* VTCR_EL2 */
+    } else {
+        return extract32(tcr, 20, 1);
+    }
+}
+
+static int aa64_va_parameter_tbid(uint64_t tcr, ARMMMUIdx mmu_idx)
+{
+    if (regime_has_2_ranges(mmu_idx)) {
+        return extract64(tcr, 51, 2);
+    } else if (mmu_idx == ARMMMUIdx_Stage2) {
+        return 0; /* VTCR_EL2 */
+    } else {
+        return extract32(tcr, 29, 1);
+    }
+}
+
+ARMVAParameters aa64_va_parameters(CPUARMState *env, uint64_t va,
+                                   ARMMMUIdx mmu_idx, bool data)
 {
     uint64_t tcr = regime_tcr(env, mmu_idx)->raw_tcr;
-    bool tbi, tbid, epd, hpd, using16k, using64k;
-    int select, tsz;
+    bool epd, hpd, using16k, using64k;
+    int select, tsz, tbi;
 
     if (!regime_has_2_ranges(mmu_idx)) {
         select = 0;
@@ -10248,11 +10270,9 @@ ARMVAParameters aa64_va_parameters_both(CPUARMState *env, uint64_t va,
         using16k = extract32(tcr, 15, 1);
         if (mmu_idx == ARMMMUIdx_Stage2) {
             /* VTCR_EL2 */
-            tbi = tbid = hpd = false;
+            hpd = false;
         } else {
-            tbi = extract32(tcr, 20, 1);
             hpd = extract32(tcr, 24, 1);
-            tbid = extract32(tcr, 29, 1);
         }
         epd = false;
     } else {
@@ -10266,28 +10286,30 @@ ARMVAParameters aa64_va_parameters_both(CPUARMState *env, uint64_t va,
             epd = extract32(tcr, 7, 1);
             using64k = extract32(tcr, 14, 1);
             using16k = extract32(tcr, 15, 1);
-            tbi = extract64(tcr, 37, 1);
             hpd = extract64(tcr, 41, 1);
-            tbid = extract64(tcr, 51, 1);
         } else {
             int tg = extract32(tcr, 30, 2);
             using16k = tg == 1;
             using64k = tg == 3;
             tsz = extract32(tcr, 16, 6);
             epd = extract32(tcr, 23, 1);
-            tbi = extract64(tcr, 38, 1);
             hpd = extract64(tcr, 42, 1);
-            tbid = extract64(tcr, 52, 1);
         }
     }
     tsz = MIN(tsz, 39);  /* TODO: ARMv8.4-TTST */
     tsz = MAX(tsz, 16);  /* TODO: ARMv8.2-LVA  */
 
+    /* Present TBI as a composite with TBID.  */
+    tbi = aa64_va_parameter_tbi(tcr, mmu_idx);
+    if (!data) {
+        tbi &= ~aa64_va_parameter_tbid(tcr, mmu_idx);
+    }
+    tbi = (tbi >> select) & 1;
+
     return (ARMVAParameters) {
         .tsz = tsz,
         .select = select,
         .tbi = tbi,
-        .tbid = tbid,
         .epd = epd,
         .hpd = hpd,
         .using16k = using16k,
@@ -10295,16 +10317,6 @@ ARMVAParameters aa64_va_parameters_both(CPUARMState *env, uint64_t va,
     };
 }
 
-ARMVAParameters aa64_va_parameters(CPUARMState *env, uint64_t va,
-                                   ARMMMUIdx mmu_idx, bool data)
-{
-    ARMVAParameters ret = aa64_va_parameters_both(env, va, mmu_idx);
-
-    /* Present TBI as a composite with TBID.  */
-    ret.tbi &= (data || !ret.tbid);
-    return ret;
-}
-
 #ifndef CONFIG_USER_ONLY
 static ARMVAParameters aa32_va_parameters(CPUARMState *env, uint32_t va,
                                           ARMMMUIdx mmu_idx)
@@ -12134,21 +12146,15 @@ static uint32_t rebuild_hflags_a64(CPUARMState *env, int el, int fp_el,
 {
     uint32_t flags = rebuild_hflags_aprofile(env);
     ARMMMUIdx stage1 = stage_1_mmu_idx(mmu_idx);
-    ARMVAParameters p0 = aa64_va_parameters_both(env, 0, stage1);
+    uint64_t tcr = regime_tcr(env, mmu_idx)->raw_tcr;
     uint64_t sctlr;
     int tbii, tbid;
 
     flags = FIELD_DP32(flags, TBFLAG_ANY, AARCH64_STATE, 1);
 
     /* Get control bits for tagged addresses.  */
-    if (regime_has_2_ranges(mmu_idx)) {
-        ARMVAParameters p1 = aa64_va_parameters_both(env, -1, stage1);
-        tbid = (p1.tbi << 1) | p0.tbi;
-        tbii = tbid & ~((p1.tbid << 1) | p0.tbid);
-    } else {
-        tbid = p0.tbi;
-        tbii = tbid & !p0.tbid;
-    }
+    tbid = aa64_va_parameter_tbi(tcr, mmu_idx);
+    tbii = tbid & ~aa64_va_parameter_tbid(tcr, mmu_idx);
 
     flags = FIELD_DP32(flags, TBFLAG_A64, TBII, tbii);
     flags = FIELD_DP32(flags, TBFLAG_A64, TBID, tbid);
-- 
2.20.1

Re: [PATCH v3 0/4] target/arm: Reduce aa64_va_parameter overhead

[Peter Maydell]

On Sun, 16 Feb 2020 at 19:43, Richard Henderson
<richard.henderson@linaro.org> wrote:
>
> Something I noticed while developing and testing VHE.
>
> For v2, fix select as a separate patch.
> For v3, adjust pauth to use bit 55 explicitly, and remove a
> now duplicate test within get_phys_addr_lpae.
>



Applied to target-arm.next, thanks.

-- PMM