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[PATCH] hvf: arm: Fix encodings for ID_AA64PFR1_EL1 and debug System registers

Zenghui Yu posted 1 patch 2 weeks ago
Patches applied successfully (tree, apply log)
git fetch https://github.com/patchew-project/qemu tags/patchew/20240503153453.54389-1-zenghui.yu@linux.dev
Maintainers: Alexander Graf <agraf@csgraf.de>, Peter Maydell <peter.maydell@linaro.org>
target/arm/hvf/hvf.c | 160 +++++++++++++++++++++----------------------
1 file changed, 80 insertions(+), 80 deletions(-)
[PATCH] hvf: arm: Fix encodings for ID_AA64PFR1_EL1 and debug System registers
Posted by Zenghui Yu 2 weeks ago 
We wrongly encoded ID_AA64PFR1_EL1 using {3,0,0,4,2} in hvf_sreg_match[] so
we fail to get the expected ARMCPRegInfo from cp_regs hash table with the
wrong key.

Fix it with the correct encoding {3,0,0,4,1}. With that fixed, the Linux
guest can properly detect FEAT_SSBS2 on my M1 HW.

All DBG{B,W}{V,C}R_EL1 registers are also wrongly encoded with op0 == 14.
It happens to work because HVF_SYSREG(CRn, CRm, 14, op1, op2) equals to
HVF_SYSREG(CRn, CRm, 2, op1, op2), by definition. But we shouldn't rely on
it.

Fixes: a1477da3ddeb ("hvf: Add Apple Silicon support")
Signed-off-by: Zenghui Yu <zenghui.yu@linux.dev>
---
 target/arm/hvf/hvf.c | 160 +++++++++++++++++++++----------------------
 1 file changed, 80 insertions(+), 80 deletions(-)

diff --git a/target/arm/hvf/hvf.c b/target/arm/hvf/hvf.c
index 08d0757438..45e2218be5 100644
--- a/target/arm/hvf/hvf.c
+++ b/target/arm/hvf/hvf.c
@@ -396,85 +396,85 @@ struct hvf_sreg_match {
 };
 
 static struct hvf_sreg_match hvf_sreg_match[] = {
-    { HV_SYS_REG_DBGBVR0_EL1, HVF_SYSREG(0, 0, 14, 0, 4) },
-    { HV_SYS_REG_DBGBCR0_EL1, HVF_SYSREG(0, 0, 14, 0, 5) },
-    { HV_SYS_REG_DBGWVR0_EL1, HVF_SYSREG(0, 0, 14, 0, 6) },
-    { HV_SYS_REG_DBGWCR0_EL1, HVF_SYSREG(0, 0, 14, 0, 7) },
-
-    { HV_SYS_REG_DBGBVR1_EL1, HVF_SYSREG(0, 1, 14, 0, 4) },
-    { HV_SYS_REG_DBGBCR1_EL1, HVF_SYSREG(0, 1, 14, 0, 5) },
-    { HV_SYS_REG_DBGWVR1_EL1, HVF_SYSREG(0, 1, 14, 0, 6) },
-    { HV_SYS_REG_DBGWCR1_EL1, HVF_SYSREG(0, 1, 14, 0, 7) },
-
-    { HV_SYS_REG_DBGBVR2_EL1, HVF_SYSREG(0, 2, 14, 0, 4) },
-    { HV_SYS_REG_DBGBCR2_EL1, HVF_SYSREG(0, 2, 14, 0, 5) },
-    { HV_SYS_REG_DBGWVR2_EL1, HVF_SYSREG(0, 2, 14, 0, 6) },
-    { HV_SYS_REG_DBGWCR2_EL1, HVF_SYSREG(0, 2, 14, 0, 7) },
-
-    { HV_SYS_REG_DBGBVR3_EL1, HVF_SYSREG(0, 3, 14, 0, 4) },
-    { HV_SYS_REG_DBGBCR3_EL1, HVF_SYSREG(0, 3, 14, 0, 5) },
-    { HV_SYS_REG_DBGWVR3_EL1, HVF_SYSREG(0, 3, 14, 0, 6) },
-    { HV_SYS_REG_DBGWCR3_EL1, HVF_SYSREG(0, 3, 14, 0, 7) },
-
-    { HV_SYS_REG_DBGBVR4_EL1, HVF_SYSREG(0, 4, 14, 0, 4) },
-    { HV_SYS_REG_DBGBCR4_EL1, HVF_SYSREG(0, 4, 14, 0, 5) },
-    { HV_SYS_REG_DBGWVR4_EL1, HVF_SYSREG(0, 4, 14, 0, 6) },
-    { HV_SYS_REG_DBGWCR4_EL1, HVF_SYSREG(0, 4, 14, 0, 7) },
-
-    { HV_SYS_REG_DBGBVR5_EL1, HVF_SYSREG(0, 5, 14, 0, 4) },
-    { HV_SYS_REG_DBGBCR5_EL1, HVF_SYSREG(0, 5, 14, 0, 5) },
-    { HV_SYS_REG_DBGWVR5_EL1, HVF_SYSREG(0, 5, 14, 0, 6) },
-    { HV_SYS_REG_DBGWCR5_EL1, HVF_SYSREG(0, 5, 14, 0, 7) },
-
-    { HV_SYS_REG_DBGBVR6_EL1, HVF_SYSREG(0, 6, 14, 0, 4) },
-    { HV_SYS_REG_DBGBCR6_EL1, HVF_SYSREG(0, 6, 14, 0, 5) },
-    { HV_SYS_REG_DBGWVR6_EL1, HVF_SYSREG(0, 6, 14, 0, 6) },
-    { HV_SYS_REG_DBGWCR6_EL1, HVF_SYSREG(0, 6, 14, 0, 7) },
-
-    { HV_SYS_REG_DBGBVR7_EL1, HVF_SYSREG(0, 7, 14, 0, 4) },
-    { HV_SYS_REG_DBGBCR7_EL1, HVF_SYSREG(0, 7, 14, 0, 5) },
-    { HV_SYS_REG_DBGWVR7_EL1, HVF_SYSREG(0, 7, 14, 0, 6) },
-    { HV_SYS_REG_DBGWCR7_EL1, HVF_SYSREG(0, 7, 14, 0, 7) },
-
-    { HV_SYS_REG_DBGBVR8_EL1, HVF_SYSREG(0, 8, 14, 0, 4) },
-    { HV_SYS_REG_DBGBCR8_EL1, HVF_SYSREG(0, 8, 14, 0, 5) },
-    { HV_SYS_REG_DBGWVR8_EL1, HVF_SYSREG(0, 8, 14, 0, 6) },
-    { HV_SYS_REG_DBGWCR8_EL1, HVF_SYSREG(0, 8, 14, 0, 7) },
-
-    { HV_SYS_REG_DBGBVR9_EL1, HVF_SYSREG(0, 9, 14, 0, 4) },
-    { HV_SYS_REG_DBGBCR9_EL1, HVF_SYSREG(0, 9, 14, 0, 5) },
-    { HV_SYS_REG_DBGWVR9_EL1, HVF_SYSREG(0, 9, 14, 0, 6) },
-    { HV_SYS_REG_DBGWCR9_EL1, HVF_SYSREG(0, 9, 14, 0, 7) },
-
-    { HV_SYS_REG_DBGBVR10_EL1, HVF_SYSREG(0, 10, 14, 0, 4) },
-    { HV_SYS_REG_DBGBCR10_EL1, HVF_SYSREG(0, 10, 14, 0, 5) },
-    { HV_SYS_REG_DBGWVR10_EL1, HVF_SYSREG(0, 10, 14, 0, 6) },
-    { HV_SYS_REG_DBGWCR10_EL1, HVF_SYSREG(0, 10, 14, 0, 7) },
-
-    { HV_SYS_REG_DBGBVR11_EL1, HVF_SYSREG(0, 11, 14, 0, 4) },
-    { HV_SYS_REG_DBGBCR11_EL1, HVF_SYSREG(0, 11, 14, 0, 5) },
-    { HV_SYS_REG_DBGWVR11_EL1, HVF_SYSREG(0, 11, 14, 0, 6) },
-    { HV_SYS_REG_DBGWCR11_EL1, HVF_SYSREG(0, 11, 14, 0, 7) },
-
-    { HV_SYS_REG_DBGBVR12_EL1, HVF_SYSREG(0, 12, 14, 0, 4) },
-    { HV_SYS_REG_DBGBCR12_EL1, HVF_SYSREG(0, 12, 14, 0, 5) },
-    { HV_SYS_REG_DBGWVR12_EL1, HVF_SYSREG(0, 12, 14, 0, 6) },
-    { HV_SYS_REG_DBGWCR12_EL1, HVF_SYSREG(0, 12, 14, 0, 7) },
-
-    { HV_SYS_REG_DBGBVR13_EL1, HVF_SYSREG(0, 13, 14, 0, 4) },
-    { HV_SYS_REG_DBGBCR13_EL1, HVF_SYSREG(0, 13, 14, 0, 5) },
-    { HV_SYS_REG_DBGWVR13_EL1, HVF_SYSREG(0, 13, 14, 0, 6) },
-    { HV_SYS_REG_DBGWCR13_EL1, HVF_SYSREG(0, 13, 14, 0, 7) },
-
-    { HV_SYS_REG_DBGBVR14_EL1, HVF_SYSREG(0, 14, 14, 0, 4) },
-    { HV_SYS_REG_DBGBCR14_EL1, HVF_SYSREG(0, 14, 14, 0, 5) },
-    { HV_SYS_REG_DBGWVR14_EL1, HVF_SYSREG(0, 14, 14, 0, 6) },
-    { HV_SYS_REG_DBGWCR14_EL1, HVF_SYSREG(0, 14, 14, 0, 7) },
-
-    { HV_SYS_REG_DBGBVR15_EL1, HVF_SYSREG(0, 15, 14, 0, 4) },
-    { HV_SYS_REG_DBGBCR15_EL1, HVF_SYSREG(0, 15, 14, 0, 5) },
-    { HV_SYS_REG_DBGWVR15_EL1, HVF_SYSREG(0, 15, 14, 0, 6) },
-    { HV_SYS_REG_DBGWCR15_EL1, HVF_SYSREG(0, 15, 14, 0, 7) },
+    { HV_SYS_REG_DBGBVR0_EL1, HVF_SYSREG(0, 0, 2, 0, 4) },
+    { HV_SYS_REG_DBGBCR0_EL1, HVF_SYSREG(0, 0, 2, 0, 5) },
+    { HV_SYS_REG_DBGWVR0_EL1, HVF_SYSREG(0, 0, 2, 0, 6) },
+    { HV_SYS_REG_DBGWCR0_EL1, HVF_SYSREG(0, 0, 2, 0, 7) },
+
+    { HV_SYS_REG_DBGBVR1_EL1, HVF_SYSREG(0, 1, 2, 0, 4) },
+    { HV_SYS_REG_DBGBCR1_EL1, HVF_SYSREG(0, 1, 2, 0, 5) },
+    { HV_SYS_REG_DBGWVR1_EL1, HVF_SYSREG(0, 1, 2, 0, 6) },
+    { HV_SYS_REG_DBGWCR1_EL1, HVF_SYSREG(0, 1, 2, 0, 7) },
+
+    { HV_SYS_REG_DBGBVR2_EL1, HVF_SYSREG(0, 2, 2, 0, 4) },
+    { HV_SYS_REG_DBGBCR2_EL1, HVF_SYSREG(0, 2, 2, 0, 5) },
+    { HV_SYS_REG_DBGWVR2_EL1, HVF_SYSREG(0, 2, 2, 0, 6) },
+    { HV_SYS_REG_DBGWCR2_EL1, HVF_SYSREG(0, 2, 2, 0, 7) },
+
+    { HV_SYS_REG_DBGBVR3_EL1, HVF_SYSREG(0, 3, 2, 0, 4) },
+    { HV_SYS_REG_DBGBCR3_EL1, HVF_SYSREG(0, 3, 2, 0, 5) },
+    { HV_SYS_REG_DBGWVR3_EL1, HVF_SYSREG(0, 3, 2, 0, 6) },
+    { HV_SYS_REG_DBGWCR3_EL1, HVF_SYSREG(0, 3, 2, 0, 7) },
+
+    { HV_SYS_REG_DBGBVR4_EL1, HVF_SYSREG(0, 4, 2, 0, 4) },
+    { HV_SYS_REG_DBGBCR4_EL1, HVF_SYSREG(0, 4, 2, 0, 5) },
+    { HV_SYS_REG_DBGWVR4_EL1, HVF_SYSREG(0, 4, 2, 0, 6) },
+    { HV_SYS_REG_DBGWCR4_EL1, HVF_SYSREG(0, 4, 2, 0, 7) },
+
+    { HV_SYS_REG_DBGBVR5_EL1, HVF_SYSREG(0, 5, 2, 0, 4) },
+    { HV_SYS_REG_DBGBCR5_EL1, HVF_SYSREG(0, 5, 2, 0, 5) },
+    { HV_SYS_REG_DBGWVR5_EL1, HVF_SYSREG(0, 5, 2, 0, 6) },
+    { HV_SYS_REG_DBGWCR5_EL1, HVF_SYSREG(0, 5, 2, 0, 7) },
+
+    { HV_SYS_REG_DBGBVR6_EL1, HVF_SYSREG(0, 6, 2, 0, 4) },
+    { HV_SYS_REG_DBGBCR6_EL1, HVF_SYSREG(0, 6, 2, 0, 5) },
+    { HV_SYS_REG_DBGWVR6_EL1, HVF_SYSREG(0, 6, 2, 0, 6) },
+    { HV_SYS_REG_DBGWCR6_EL1, HVF_SYSREG(0, 6, 2, 0, 7) },
+
+    { HV_SYS_REG_DBGBVR7_EL1, HVF_SYSREG(0, 7, 2, 0, 4) },
+    { HV_SYS_REG_DBGBCR7_EL1, HVF_SYSREG(0, 7, 2, 0, 5) },
+    { HV_SYS_REG_DBGWVR7_EL1, HVF_SYSREG(0, 7, 2, 0, 6) },
+    { HV_SYS_REG_DBGWCR7_EL1, HVF_SYSREG(0, 7, 2, 0, 7) },
+
+    { HV_SYS_REG_DBGBVR8_EL1, HVF_SYSREG(0, 8, 2, 0, 4) },
+    { HV_SYS_REG_DBGBCR8_EL1, HVF_SYSREG(0, 8, 2, 0, 5) },
+    { HV_SYS_REG_DBGWVR8_EL1, HVF_SYSREG(0, 8, 2, 0, 6) },
+    { HV_SYS_REG_DBGWCR8_EL1, HVF_SYSREG(0, 8, 2, 0, 7) },
+
+    { HV_SYS_REG_DBGBVR9_EL1, HVF_SYSREG(0, 9, 2, 0, 4) },
+    { HV_SYS_REG_DBGBCR9_EL1, HVF_SYSREG(0, 9, 2, 0, 5) },
+    { HV_SYS_REG_DBGWVR9_EL1, HVF_SYSREG(0, 9, 2, 0, 6) },
+    { HV_SYS_REG_DBGWCR9_EL1, HVF_SYSREG(0, 9, 2, 0, 7) },
+
+    { HV_SYS_REG_DBGBVR10_EL1, HVF_SYSREG(0, 10, 2, 0, 4) },
+    { HV_SYS_REG_DBGBCR10_EL1, HVF_SYSREG(0, 10, 2, 0, 5) },
+    { HV_SYS_REG_DBGWVR10_EL1, HVF_SYSREG(0, 10, 2, 0, 6) },
+    { HV_SYS_REG_DBGWCR10_EL1, HVF_SYSREG(0, 10, 2, 0, 7) },
+
+    { HV_SYS_REG_DBGBVR11_EL1, HVF_SYSREG(0, 11, 2, 0, 4) },
+    { HV_SYS_REG_DBGBCR11_EL1, HVF_SYSREG(0, 11, 2, 0, 5) },
+    { HV_SYS_REG_DBGWVR11_EL1, HVF_SYSREG(0, 11, 2, 0, 6) },
+    { HV_SYS_REG_DBGWCR11_EL1, HVF_SYSREG(0, 11, 2, 0, 7) },
+
+    { HV_SYS_REG_DBGBVR12_EL1, HVF_SYSREG(0, 12, 2, 0, 4) },
+    { HV_SYS_REG_DBGBCR12_EL1, HVF_SYSREG(0, 12, 2, 0, 5) },
+    { HV_SYS_REG_DBGWVR12_EL1, HVF_SYSREG(0, 12, 2, 0, 6) },
+    { HV_SYS_REG_DBGWCR12_EL1, HVF_SYSREG(0, 12, 2, 0, 7) },
+
+    { HV_SYS_REG_DBGBVR13_EL1, HVF_SYSREG(0, 13, 2, 0, 4) },
+    { HV_SYS_REG_DBGBCR13_EL1, HVF_SYSREG(0, 13, 2, 0, 5) },
+    { HV_SYS_REG_DBGWVR13_EL1, HVF_SYSREG(0, 13, 2, 0, 6) },
+    { HV_SYS_REG_DBGWCR13_EL1, HVF_SYSREG(0, 13, 2, 0, 7) },
+
+    { HV_SYS_REG_DBGBVR14_EL1, HVF_SYSREG(0, 14, 2, 0, 4) },
+    { HV_SYS_REG_DBGBCR14_EL1, HVF_SYSREG(0, 14, 2, 0, 5) },
+    { HV_SYS_REG_DBGWVR14_EL1, HVF_SYSREG(0, 14, 2, 0, 6) },
+    { HV_SYS_REG_DBGWCR14_EL1, HVF_SYSREG(0, 14, 2, 0, 7) },
+
+    { HV_SYS_REG_DBGBVR15_EL1, HVF_SYSREG(0, 15, 2, 0, 4) },
+    { HV_SYS_REG_DBGBCR15_EL1, HVF_SYSREG(0, 15, 2, 0, 5) },
+    { HV_SYS_REG_DBGWVR15_EL1, HVF_SYSREG(0, 15, 2, 0, 6) },
+    { HV_SYS_REG_DBGWCR15_EL1, HVF_SYSREG(0, 15, 2, 0, 7) },
 
 #ifdef SYNC_NO_RAW_REGS
     /*
@@ -486,7 +486,7 @@ static struct hvf_sreg_match hvf_sreg_match[] = {
     { HV_SYS_REG_MPIDR_EL1, HVF_SYSREG(0, 0, 3, 0, 5) },
     { HV_SYS_REG_ID_AA64PFR0_EL1, HVF_SYSREG(0, 4, 3, 0, 0) },
 #endif
-    { HV_SYS_REG_ID_AA64PFR1_EL1, HVF_SYSREG(0, 4, 3, 0, 2) },
+    { HV_SYS_REG_ID_AA64PFR1_EL1, HVF_SYSREG(0, 4, 3, 0, 1) },
     { HV_SYS_REG_ID_AA64DFR0_EL1, HVF_SYSREG(0, 5, 3, 0, 0) },
     { HV_SYS_REG_ID_AA64DFR1_EL1, HVF_SYSREG(0, 5, 3, 0, 1) },
     { HV_SYS_REG_ID_AA64ISAR0_EL1, HVF_SYSREG(0, 6, 3, 0, 0) },
-- 
2.34.1
Re: [PATCH] hvf: arm: Fix encodings for ID_AA64PFR1_EL1 and debug System registers
Posted by Peter Maydell 1 week, 3 days ago 
On Fri, 3 May 2024 at 16:35, Zenghui Yu <zenghui.yu@linux.dev> wrote:
>
> We wrongly encoded ID_AA64PFR1_EL1 using {3,0,0,4,2} in hvf_sreg_match[] so
> we fail to get the expected ARMCPRegInfo from cp_regs hash table with the
> wrong key.
>
> Fix it with the correct encoding {3,0,0,4,1}. With that fixed, the Linux
> guest can properly detect FEAT_SSBS2 on my M1 HW.
>
> All DBG{B,W}{V,C}R_EL1 registers are also wrongly encoded with op0 == 14.
> It happens to work because HVF_SYSREG(CRn, CRm, 14, op1, op2) equals to
> HVF_SYSREG(CRn, CRm, 2, op1, op2), by definition. But we shouldn't rely on
> it.
>
> Fixes: a1477da3ddeb ("hvf: Add Apple Silicon support")
> Signed-off-by: Zenghui Yu <zenghui.yu@linux.dev>
> ---

Applied to target-arm.next, thanks. I threw in a cc:stable tag,
though it doesn't sound like the consequences of the bug are very
significant.

-- PMM
Re: [PATCH] hvf: arm: Fix encodings for ID_AA64PFR1_EL1 and debug System registers
Posted by Marcin Juszkiewicz 1 week, 5 days ago 
W dniu 3.05.2024 o 17:34, Zenghui Yu pisze:
> We wrongly encoded ID_AA64PFR1_EL1 using {3,0,0,4,2} in hvf_sreg_match[] so
> we fail to get the expected ARMCPRegInfo from cp_regs hash table with the
> wrong key.
> 
> Fix it with the correct encoding {3,0,0,4,1}. With that fixed, the Linux
> guest can properly detect FEAT_SSBS2 on my M1 HW.
> 
> All DBG{B,W}{V,C}R_EL1 registers are also wrongly encoded with op0 == 14.
> It happens to work because HVF_SYSREG(CRn, CRm, 14, op1, op2) equals to
> HVF_SYSREG(CRn, CRm, 2, op1, op2), by definition. But we shouldn't rely on
> it.
> 
> Fixes: a1477da3ddeb ("hvf: Add Apple Silicon support")
> Signed-off-by: Zenghui Yu<zenghui.yu@linux.dev>

If your boot environment allows to run EFI binaries then my ArmCpuInfo 
app [1] can be used to check values of system registers and flags 
present in them.

https://github.com/hrw/edk2-armcpuinfo/releases/tag/v1.2.0

Example header:

ArmCpuInfo v1.2.0

ID_AA64MMFR0_EL1 = 0x0100032310201126
ID_AA64MMFR1_EL1 = 0x0010011010312122
ID_AA64MMFR2_EL1 = 0x1221011112011011
ID_AA64PFR0_EL1  = 0x1201001121112222
ID_AA64PFR1_EL1  = 0x0000000001000121
ID_AA64ISAR0_EL1 = 0x1221111110212120
ID_AA64ISAR1_EL1 = 0x0011111101211052
ID_AA64ISAR2_EL1 = 0x0000000000110000
ID_AA64DFR0_EL1  = 0x1000000010305609
ID_AA64SMFR0_EL1 = 0x80F100FD00000000
ID_AA64ZFR0_EL1  = 0x0110110100110021

Have to finish work on next release - it will show also values of 
MMFR3/4, ISAR3, AFR0/1 and FPFR0 registers.
Re: [PATCH] hvf: arm: Fix encodings for ID_AA64PFR1_EL1 and debug System registers
Posted by Alexander Graf 1 week, 5 days ago 
On 03.05.24 19:34, Zenghui Yu wrote:
> We wrongly encoded ID_AA64PFR1_EL1 using {3,0,0,4,2} in hvf_sreg_match[] so
> we fail to get the expected ARMCPRegInfo from cp_regs hash table with the
> wrong key.
>
> Fix it with the correct encoding {3,0,0,4,1}. With that fixed, the Linux
> guest can properly detect FEAT_SSBS2 on my M1 HW.
>
> All DBG{B,W}{V,C}R_EL1 registers are also wrongly encoded with op0 == 14.
> It happens to work because HVF_SYSREG(CRn, CRm, 14, op1, op2) equals to
> HVF_SYSREG(CRn, CRm, 2, op1, op2), by definition. But we shouldn't rely on
> it.
>
> Fixes: a1477da3ddeb ("hvf: Add Apple Silicon support")
> Signed-off-by: Zenghui Yu <zenghui.yu@linux.dev>


Nice catch! Did you find them only because of functional issues or have 
you taken an automated pass somehow to validate the sysreg definitions 
are correct?

Reviewed-by: Alexander Graf <agraf@csgraf.de>


Alex
Re: [PATCH] hvf: arm: Fix encodings for ID_AA64PFR1_EL1 and debug System registers
Posted by Zenghui Yu 1 week, 5 days ago 
On 2024/5/5 21:18, Alexander Graf wrote:
> 
> On 03.05.24 19:34, Zenghui Yu wrote:
>> We wrongly encoded ID_AA64PFR1_EL1 using {3,0,0,4,2} in 
>> hvf_sreg_match[] so
>> we fail to get the expected ARMCPRegInfo from cp_regs hash table with the
>> wrong key.
>>
>> Fix it with the correct encoding {3,0,0,4,1}. With that fixed, the Linux
>> guest can properly detect FEAT_SSBS2 on my M1 HW.
>>
>> All DBG{B,W}{V,C}R_EL1 registers are also wrongly encoded with op0 == 14.
>> It happens to work because HVF_SYSREG(CRn, CRm, 14, op1, op2) equals to
>> HVF_SYSREG(CRn, CRm, 2, op1, op2), by definition. But we shouldn't 
>> rely on
>> it.
>>
>> Fixes: a1477da3ddeb ("hvf: Add Apple Silicon support")
>> Signed-off-by: Zenghui Yu <zenghui.yu@linux.dev>
> 
> 
> Nice catch! Did you find them only because of functional issues or have 
> you taken an automated pass somehow to validate the sysreg definitions 
> are correct?

Neither, this was found by code inspection. I was just curious about how
VMM would interact with hypervisor to expose features to the guest. Docs
at https://developer.apple.com/documentation/hypervisor are not that
detailed (I may need to read further ;-) ).

P.S., I verified on M1 that ID_AA64PFR1_EL1 is 0x20 at
hvf_arm_get_host_cpu_features() stage and is overwritten as 0x0 later
w/o this patch, which indicates the (guest visible) feature ID registers
are "writable" to some extent.

> Reviewed-by: Alexander Graf <agraf@csgraf.de>

Thanks!

Zenghui

Patchew 2.1-devel-0870f84

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