[PATCH v3 0/9] RISC-V SBI debug console extension support

[PATCH v3 0/9] RISC-V SBI debug console extension support

[Anup Patel]

The SBI v2.0 specification is now frozen. The SBI v2.0 specification defines
SBI debug console (DBCN) extension which replaces the legacy SBI v0.1
functions sbi_console_putchar() and sbi_console_getchar().
(Refer v2.0-rc5 at https://github.com/riscv-non-isa/riscv-sbi-doc/releases)

This series adds support for SBI debug console (DBCN) extension in KVM RISC-V
and Linux RISC-V.

To try these patches with KVM RISC-V, use KVMTOOL from riscv_sbi_dbcn_v1
branch at: https://github.com/avpatel/kvmtool.git

These patches can also be found in the riscv_sbi_dbcn_v3 branch at:
https://github.com/avpatel/linux.git

Changes since v2:
 - Rebased on Linux-6.6-rc5
 - Handled page-crossing in PATCH7 of v2 series
 - Addressed Drew's comment in PATCH3 of v2 series
 - Added new PATCH5 to make get-reg-list test aware of SBI DBCN extension

Changes since v1:
 - Remove use of #ifdef from PATCH4 and PATCH5 of the v1 series
 - Improved commit description of PATCH3 in v1 series
 - Introduced new PATCH3 in this series to allow some SBI extensions
   (such as SBI DBCN) do to disabled by default so that older KVM user space
   work fine and newer KVM user space have to explicitly opt-in for emulating
   SBI DBCN.
 - Introduced new PATCH5 in this series which adds inline version of
   sbi_console_getchar() and sbi_console_putchar() for the case where
   CONFIG_RISCV_SBI_V01 is disabled.

Anup Patel (8):
  RISC-V: Add defines for SBI debug console extension
  RISC-V: KVM: Change the SBI specification version to v2.0
  RISC-V: KVM: Allow some SBI extensions to be disabled by default
  RISC-V: KVM: Forward SBI DBCN extension to user-space
  KVM: riscv: selftests: Add SBI DBCN extension to get-reg-list test
  RISC-V: Add stubs for sbi_console_putchar/getchar()
  tty/serial: Add RISC-V SBI debug console based earlycon
  RISC-V: Enable SBI based earlycon support

Atish Patra (1):
  tty: Add SBI debug console support to HVC SBI driver

 arch/riscv/configs/defconfig                  |  1 +
 arch/riscv/configs/rv32_defconfig             |  1 +
 arch/riscv/include/asm/kvm_vcpu_sbi.h         |  7 +-
 arch/riscv/include/asm/sbi.h                  | 12 +++
 arch/riscv/include/uapi/asm/kvm.h             |  1 +
 arch/riscv/kvm/vcpu.c                         |  6 ++
 arch/riscv/kvm/vcpu_sbi.c                     | 61 +++++++-------
 arch/riscv/kvm/vcpu_sbi_replace.c             | 32 ++++++++
 drivers/tty/hvc/Kconfig                       |  2 +-
 drivers/tty/hvc/hvc_riscv_sbi.c               | 82 +++++++++++++++++--
 drivers/tty/serial/Kconfig                    |  2 +-
 drivers/tty/serial/earlycon-riscv-sbi.c       | 32 +++++++-
 .../selftests/kvm/riscv/get-reg-list.c        |  2 +
 13 files changed, 198 insertions(+), 43 deletions(-)

-- 
2.34.1

[PATCH v3 1/9] RISC-V: Add defines for SBI debug console extension

[Anup Patel]

We add SBI debug console extension related defines/enum to the
asm/sbi.h header.

Signed-off-by: Anup Patel <apatel@ventanamicro.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
---
 arch/riscv/include/asm/sbi.h | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/arch/riscv/include/asm/sbi.h b/arch/riscv/include/asm/sbi.h
index 5b4a1bf5f439..12dfda6bb924 100644
--- a/arch/riscv/include/asm/sbi.h
+++ b/arch/riscv/include/asm/sbi.h
@@ -30,6 +30,7 @@ enum sbi_ext_id {
 	SBI_EXT_HSM = 0x48534D,
 	SBI_EXT_SRST = 0x53525354,
 	SBI_EXT_PMU = 0x504D55,
+	SBI_EXT_DBCN = 0x4442434E,
 
 	/* Experimentals extensions must lie within this range */
 	SBI_EXT_EXPERIMENTAL_START = 0x08000000,
@@ -236,6 +237,12 @@ enum sbi_pmu_ctr_type {
 /* Flags defined for counter stop function */
 #define SBI_PMU_STOP_FLAG_RESET (1 << 0)
 
+enum sbi_ext_dbcn_fid {
+	SBI_EXT_DBCN_CONSOLE_WRITE = 0,
+	SBI_EXT_DBCN_CONSOLE_READ = 1,
+	SBI_EXT_DBCN_CONSOLE_WRITE_BYTE = 2,
+};
+
 #define SBI_SPEC_VERSION_DEFAULT	0x1
 #define SBI_SPEC_VERSION_MAJOR_SHIFT	24
 #define SBI_SPEC_VERSION_MAJOR_MASK	0x7f
-- 
2.34.1

[PATCH v3 2/9] RISC-V: KVM: Change the SBI specification version to v2.0

[Anup Patel]

We will be implementing SBI DBCN extension for KVM RISC-V so let
us change the KVM RISC-V SBI specification version to v2.0.

Signed-off-by: Anup Patel <apatel@ventanamicro.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
---
 arch/riscv/include/asm/kvm_vcpu_sbi.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/riscv/include/asm/kvm_vcpu_sbi.h b/arch/riscv/include/asm/kvm_vcpu_sbi.h
index cdcf0ff07be7..8d6d4dce8a5e 100644
--- a/arch/riscv/include/asm/kvm_vcpu_sbi.h
+++ b/arch/riscv/include/asm/kvm_vcpu_sbi.h
@@ -11,7 +11,7 @@
 
 #define KVM_SBI_IMPID 3
 
-#define KVM_SBI_VERSION_MAJOR 1
+#define KVM_SBI_VERSION_MAJOR 2
 #define KVM_SBI_VERSION_MINOR 0
 
 enum kvm_riscv_sbi_ext_status {
-- 
2.34.1

[PATCH v3 3/9] RISC-V: KVM: Allow some SBI extensions to be disabled by default

[Anup Patel]

Currently, all SBI extensions are enabled by default which is
problematic for SBI extensions (such as DBCN) which are forwarded
to the KVM user-space because we might have an older KVM user-space
which is not aware/ready to handle newer SBI extensions. Ideally,
the SBI extensions forwarded to the KVM user-space must be
disabled by default.

To address above, we allow certain SBI extensions to be disabled
by default so that KVM user-space must explicitly enable such
SBI extensions to receive forwarded calls from Guest VCPU.

Signed-off-by: Anup Patel <apatel@ventanamicro.com>
---
 arch/riscv/include/asm/kvm_vcpu_sbi.h |  4 ++
 arch/riscv/kvm/vcpu.c                 |  6 +++
 arch/riscv/kvm/vcpu_sbi.c             | 57 +++++++++++++--------------
 3 files changed, 38 insertions(+), 29 deletions(-)

diff --git a/arch/riscv/include/asm/kvm_vcpu_sbi.h b/arch/riscv/include/asm/kvm_vcpu_sbi.h
index 8d6d4dce8a5e..c02bda5559d7 100644
--- a/arch/riscv/include/asm/kvm_vcpu_sbi.h
+++ b/arch/riscv/include/asm/kvm_vcpu_sbi.h
@@ -35,6 +35,9 @@ struct kvm_vcpu_sbi_return {
 struct kvm_vcpu_sbi_extension {
 	unsigned long extid_start;
 	unsigned long extid_end;
+
+	bool default_unavail;
+
 	/**
 	 * SBI extension handler. It can be defined for a given extension or group of
 	 * extension. But it should always return linux error codes rather than SBI
@@ -59,6 +62,7 @@ int kvm_riscv_vcpu_get_reg_sbi_ext(struct kvm_vcpu *vcpu,
 const struct kvm_vcpu_sbi_extension *kvm_vcpu_sbi_find_ext(
 				struct kvm_vcpu *vcpu, unsigned long extid);
 int kvm_riscv_vcpu_sbi_ecall(struct kvm_vcpu *vcpu, struct kvm_run *run);
+void kvm_riscv_vcpu_sbi_init(struct kvm_vcpu *vcpu);
 
 #ifdef CONFIG_RISCV_SBI_V01
 extern const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_v01;
diff --git a/arch/riscv/kvm/vcpu.c b/arch/riscv/kvm/vcpu.c
index c061a1c5fe98..e087c809073c 100644
--- a/arch/riscv/kvm/vcpu.c
+++ b/arch/riscv/kvm/vcpu.c
@@ -141,6 +141,12 @@ int kvm_arch_vcpu_create(struct kvm_vcpu *vcpu)
 	if (rc)
 		return rc;
 
+	/*
+	 * Setup SBI extensions
+	 * NOTE: This must be the last thing to be initialized.
+	 */
+	kvm_riscv_vcpu_sbi_init(vcpu);
+
 	/* Reset VCPU */
 	kvm_riscv_reset_vcpu(vcpu);
 
diff --git a/arch/riscv/kvm/vcpu_sbi.c b/arch/riscv/kvm/vcpu_sbi.c
index 9cd97091c723..bda8b0b33343 100644
--- a/arch/riscv/kvm/vcpu_sbi.c
+++ b/arch/riscv/kvm/vcpu_sbi.c
@@ -155,14 +155,8 @@ static int riscv_vcpu_set_sbi_ext_single(struct kvm_vcpu *vcpu,
 	if (!sext)
 		return -ENOENT;
 
-	/*
-	 * We can't set the extension status to available here, since it may
-	 * have a probe() function which needs to confirm availability first,
-	 * but it may be too early to call that here. We can set the status to
-	 * unavailable, though.
-	 */
-	if (!reg_val)
-		scontext->ext_status[sext->ext_idx] =
+	scontext->ext_status[sext->ext_idx] = (reg_val) ?
+			KVM_RISCV_SBI_EXT_AVAILABLE :
 			KVM_RISCV_SBI_EXT_UNAVAILABLE;
 
 	return 0;
@@ -188,16 +182,8 @@ static int riscv_vcpu_get_sbi_ext_single(struct kvm_vcpu *vcpu,
 	if (!sext)
 		return -ENOENT;
 
-	/*
-	 * If the extension status is still uninitialized, then we should probe
-	 * to determine if it's available, but it may be too early to do that
-	 * here. The best we can do is report that the extension has not been
-	 * disabled, i.e. we return 1 when the extension is available and also
-	 * when it only may be available.
-	 */
-	*reg_val = scontext->ext_status[sext->ext_idx] !=
-				KVM_RISCV_SBI_EXT_UNAVAILABLE;
-
+	*reg_val = scontext->ext_status[sext->ext_idx] ==
+				KVM_RISCV_SBI_EXT_AVAILABLE;
 	return 0;
 }
 
@@ -337,18 +323,8 @@ const struct kvm_vcpu_sbi_extension *kvm_vcpu_sbi_find_ext(
 			    scontext->ext_status[entry->ext_idx] ==
 						KVM_RISCV_SBI_EXT_AVAILABLE)
 				return ext;
-			if (scontext->ext_status[entry->ext_idx] ==
-						KVM_RISCV_SBI_EXT_UNAVAILABLE)
-				return NULL;
-			if (ext->probe && !ext->probe(vcpu)) {
-				scontext->ext_status[entry->ext_idx] =
-					KVM_RISCV_SBI_EXT_UNAVAILABLE;
-				return NULL;
-			}
 
-			scontext->ext_status[entry->ext_idx] =
-				KVM_RISCV_SBI_EXT_AVAILABLE;
-			return ext;
+			return NULL;
 		}
 	}
 
@@ -419,3 +395,26 @@ int kvm_riscv_vcpu_sbi_ecall(struct kvm_vcpu *vcpu, struct kvm_run *run)
 
 	return ret;
 }
+
+void kvm_riscv_vcpu_sbi_init(struct kvm_vcpu *vcpu)
+{
+	struct kvm_vcpu_sbi_context *scontext = &vcpu->arch.sbi_context;
+	const struct kvm_riscv_sbi_extension_entry *entry;
+	const struct kvm_vcpu_sbi_extension *ext;
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(sbi_ext); i++) {
+		entry = &sbi_ext[i];
+		ext = entry->ext_ptr;
+
+		if (ext->probe && !ext->probe(vcpu)) {
+			scontext->ext_status[entry->ext_idx] =
+				KVM_RISCV_SBI_EXT_UNAVAILABLE;
+			continue;
+		}
+
+		scontext->ext_status[entry->ext_idx] = ext->default_unavail ?
+					KVM_RISCV_SBI_EXT_UNAVAILABLE :
+					KVM_RISCV_SBI_EXT_AVAILABLE;
+	}
+}
-- 
2.34.1

Re: [PATCH v3 3/9] RISC-V: KVM: Allow some SBI extensions to be disabled by default

[Andrew Jones]

On Fri, Oct 20, 2023 at 12:51:34PM +0530, Anup Patel wrote:
> Currently, all SBI extensions are enabled by default which is
> problematic for SBI extensions (such as DBCN) which are forwarded
> to the KVM user-space because we might have an older KVM user-space
> which is not aware/ready to handle newer SBI extensions. Ideally,
> the SBI extensions forwarded to the KVM user-space must be
> disabled by default.
> 
> To address above, we allow certain SBI extensions to be disabled
> by default so that KVM user-space must explicitly enable such
> SBI extensions to receive forwarded calls from Guest VCPU.
> 
> Signed-off-by: Anup Patel <apatel@ventanamicro.com>
> ---
>  arch/riscv/include/asm/kvm_vcpu_sbi.h |  4 ++
>  arch/riscv/kvm/vcpu.c                 |  6 +++
>  arch/riscv/kvm/vcpu_sbi.c             | 57 +++++++++++++--------------
>  3 files changed, 38 insertions(+), 29 deletions(-)
>

Reviewed-by: Andrew Jones <ajones@ventanamicro.com>

[PATCH v3 4/9] RISC-V: KVM: Forward SBI DBCN extension to user-space

[Anup Patel]

The frozen SBI v2.0 specification defines the SBI debug console
(DBCN) extension which replaces the legacy SBI v0.1 console
functions namely sbi_console_getchar() and sbi_console_putchar().

The SBI DBCN extension needs to be emulated in the KVM user-space
(i.e. QEMU-KVM or KVMTOOL) so we forward SBI DBCN calls from KVM
guest to the KVM user-space which can then redirect the console
input/output to wherever it wants (e.g. telnet, file, stdio, etc).

The SBI debug console is simply a early console available to KVM
guest for early prints and it does not intend to replace the proper
console devices such as 8250, VirtIO console, etc.

Signed-off-by: Anup Patel <apatel@ventanamicro.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
---
 arch/riscv/include/asm/kvm_vcpu_sbi.h |  1 +
 arch/riscv/include/uapi/asm/kvm.h     |  1 +
 arch/riscv/kvm/vcpu_sbi.c             |  4 ++++
 arch/riscv/kvm/vcpu_sbi_replace.c     | 32 +++++++++++++++++++++++++++
 4 files changed, 38 insertions(+)

diff --git a/arch/riscv/include/asm/kvm_vcpu_sbi.h b/arch/riscv/include/asm/kvm_vcpu_sbi.h
index c02bda5559d7..6a453f7f8b56 100644
--- a/arch/riscv/include/asm/kvm_vcpu_sbi.h
+++ b/arch/riscv/include/asm/kvm_vcpu_sbi.h
@@ -73,6 +73,7 @@ extern const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_ipi;
 extern const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_rfence;
 extern const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_srst;
 extern const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_hsm;
+extern const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_dbcn;
 extern const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_experimental;
 extern const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_vendor;
 
diff --git a/arch/riscv/include/uapi/asm/kvm.h b/arch/riscv/include/uapi/asm/kvm.h
index 917d8cc2489e..60d3b21dead7 100644
--- a/arch/riscv/include/uapi/asm/kvm.h
+++ b/arch/riscv/include/uapi/asm/kvm.h
@@ -156,6 +156,7 @@ enum KVM_RISCV_SBI_EXT_ID {
 	KVM_RISCV_SBI_EXT_PMU,
 	KVM_RISCV_SBI_EXT_EXPERIMENTAL,
 	KVM_RISCV_SBI_EXT_VENDOR,
+	KVM_RISCV_SBI_EXT_DBCN,
 	KVM_RISCV_SBI_EXT_MAX,
 };
 
diff --git a/arch/riscv/kvm/vcpu_sbi.c b/arch/riscv/kvm/vcpu_sbi.c
index bda8b0b33343..a04ff98085d9 100644
--- a/arch/riscv/kvm/vcpu_sbi.c
+++ b/arch/riscv/kvm/vcpu_sbi.c
@@ -66,6 +66,10 @@ static const struct kvm_riscv_sbi_extension_entry sbi_ext[] = {
 		.ext_idx = KVM_RISCV_SBI_EXT_PMU,
 		.ext_ptr = &vcpu_sbi_ext_pmu,
 	},
+	{
+		.ext_idx = KVM_RISCV_SBI_EXT_DBCN,
+		.ext_ptr = &vcpu_sbi_ext_dbcn,
+	},
 	{
 		.ext_idx = KVM_RISCV_SBI_EXT_EXPERIMENTAL,
 		.ext_ptr = &vcpu_sbi_ext_experimental,
diff --git a/arch/riscv/kvm/vcpu_sbi_replace.c b/arch/riscv/kvm/vcpu_sbi_replace.c
index 7c4d5d38a339..23b57c931b15 100644
--- a/arch/riscv/kvm/vcpu_sbi_replace.c
+++ b/arch/riscv/kvm/vcpu_sbi_replace.c
@@ -175,3 +175,35 @@ const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_srst = {
 	.extid_end = SBI_EXT_SRST,
 	.handler = kvm_sbi_ext_srst_handler,
 };
+
+static int kvm_sbi_ext_dbcn_handler(struct kvm_vcpu *vcpu,
+				    struct kvm_run *run,
+				    struct kvm_vcpu_sbi_return *retdata)
+{
+	struct kvm_cpu_context *cp = &vcpu->arch.guest_context;
+	unsigned long funcid = cp->a6;
+
+	switch (funcid) {
+	case SBI_EXT_DBCN_CONSOLE_WRITE:
+	case SBI_EXT_DBCN_CONSOLE_READ:
+	case SBI_EXT_DBCN_CONSOLE_WRITE_BYTE:
+		/*
+		 * The SBI debug console functions are unconditionally
+		 * forwarded to the userspace.
+		 */
+		kvm_riscv_vcpu_sbi_forward(vcpu, run);
+		retdata->uexit = true;
+		break;
+	default:
+		retdata->err_val = SBI_ERR_NOT_SUPPORTED;
+	}
+
+	return 0;
+}
+
+const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_dbcn = {
+	.extid_start = SBI_EXT_DBCN,
+	.extid_end = SBI_EXT_DBCN,
+	.default_unavail = true,
+	.handler = kvm_sbi_ext_dbcn_handler,
+};
-- 
2.34.1

[PATCH v3 5/9] KVM: riscv: selftests: Add SBI DBCN extension to get-reg-list test

[Anup Patel]

We have a new SBI debug console (DBCN) extension supported by in-kernel
KVM so let us add this extension to get-reg-list test.

Signed-off-by: Anup Patel <apatel@ventanamicro.com>
---
 tools/testing/selftests/kvm/riscv/get-reg-list.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/tools/testing/selftests/kvm/riscv/get-reg-list.c b/tools/testing/selftests/kvm/riscv/get-reg-list.c
index 234006d035c9..6bedaea95395 100644
--- a/tools/testing/selftests/kvm/riscv/get-reg-list.c
+++ b/tools/testing/selftests/kvm/riscv/get-reg-list.c
@@ -394,6 +394,7 @@ static const char *sbi_ext_single_id_to_str(__u64 reg_off)
 		KVM_SBI_EXT_ARR(KVM_RISCV_SBI_EXT_PMU),
 		KVM_SBI_EXT_ARR(KVM_RISCV_SBI_EXT_EXPERIMENTAL),
 		KVM_SBI_EXT_ARR(KVM_RISCV_SBI_EXT_VENDOR),
+		KVM_SBI_EXT_ARR(KVM_RISCV_SBI_EXT_DBCN),
 	};
 
 	if (reg_off >= ARRAY_SIZE(kvm_sbi_ext_reg_name))
@@ -567,6 +568,7 @@ static __u64 base_regs[] = {
 	KVM_REG_RISCV | KVM_REG_SIZE_ULONG | KVM_REG_RISCV_SBI_EXT | KVM_REG_RISCV_SBI_SINGLE | KVM_RISCV_SBI_EXT_PMU,
 	KVM_REG_RISCV | KVM_REG_SIZE_ULONG | KVM_REG_RISCV_SBI_EXT | KVM_REG_RISCV_SBI_SINGLE | KVM_RISCV_SBI_EXT_EXPERIMENTAL,
 	KVM_REG_RISCV | KVM_REG_SIZE_ULONG | KVM_REG_RISCV_SBI_EXT | KVM_REG_RISCV_SBI_SINGLE | KVM_RISCV_SBI_EXT_VENDOR,
+	KVM_REG_RISCV | KVM_REG_SIZE_ULONG | KVM_REG_RISCV_SBI_EXT | KVM_REG_RISCV_SBI_SINGLE | KVM_RISCV_SBI_EXT_DBCN,
 	KVM_REG_RISCV | KVM_REG_SIZE_ULONG | KVM_REG_RISCV_SBI_EXT | KVM_REG_RISCV_SBI_MULTI_EN | 0,
 	KVM_REG_RISCV | KVM_REG_SIZE_ULONG | KVM_REG_RISCV_SBI_EXT | KVM_REG_RISCV_SBI_MULTI_DIS | 0,
 };
-- 
2.34.1

Re: [PATCH v3 5/9] KVM: riscv: selftests: Add SBI DBCN extension to get-reg-list test

[Andrew Jones]

On Fri, Oct 20, 2023 at 12:51:36PM +0530, Anup Patel wrote:
> We have a new SBI debug console (DBCN) extension supported by in-kernel
> KVM so let us add this extension to get-reg-list test.
> 
> Signed-off-by: Anup Patel <apatel@ventanamicro.com>
> ---
>  tools/testing/selftests/kvm/riscv/get-reg-list.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/tools/testing/selftests/kvm/riscv/get-reg-list.c b/tools/testing/selftests/kvm/riscv/get-reg-list.c
> index 234006d035c9..6bedaea95395 100644
> --- a/tools/testing/selftests/kvm/riscv/get-reg-list.c
> +++ b/tools/testing/selftests/kvm/riscv/get-reg-list.c
> @@ -394,6 +394,7 @@ static const char *sbi_ext_single_id_to_str(__u64 reg_off)
>  		KVM_SBI_EXT_ARR(KVM_RISCV_SBI_EXT_PMU),
>  		KVM_SBI_EXT_ARR(KVM_RISCV_SBI_EXT_EXPERIMENTAL),
>  		KVM_SBI_EXT_ARR(KVM_RISCV_SBI_EXT_VENDOR),
> +		KVM_SBI_EXT_ARR(KVM_RISCV_SBI_EXT_DBCN),
>  	};
>  
>  	if (reg_off >= ARRAY_SIZE(kvm_sbi_ext_reg_name))
> @@ -567,6 +568,7 @@ static __u64 base_regs[] = {
>  	KVM_REG_RISCV | KVM_REG_SIZE_ULONG | KVM_REG_RISCV_SBI_EXT | KVM_REG_RISCV_SBI_SINGLE | KVM_RISCV_SBI_EXT_PMU,
>  	KVM_REG_RISCV | KVM_REG_SIZE_ULONG | KVM_REG_RISCV_SBI_EXT | KVM_REG_RISCV_SBI_SINGLE | KVM_RISCV_SBI_EXT_EXPERIMENTAL,
>  	KVM_REG_RISCV | KVM_REG_SIZE_ULONG | KVM_REG_RISCV_SBI_EXT | KVM_REG_RISCV_SBI_SINGLE | KVM_RISCV_SBI_EXT_VENDOR,
> +	KVM_REG_RISCV | KVM_REG_SIZE_ULONG | KVM_REG_RISCV_SBI_EXT | KVM_REG_RISCV_SBI_SINGLE | KVM_RISCV_SBI_EXT_DBCN,
>  	KVM_REG_RISCV | KVM_REG_SIZE_ULONG | KVM_REG_RISCV_SBI_EXT | KVM_REG_RISCV_SBI_MULTI_EN | 0,
>  	KVM_REG_RISCV | KVM_REG_SIZE_ULONG | KVM_REG_RISCV_SBI_EXT | KVM_REG_RISCV_SBI_MULTI_DIS | 0,
>  };
> -- 
> 2.34.1
>

Reviewed-by: Andrew Jones <ajones@ventanamicro.com>

[PATCH v3 6/9] RISC-V: Add stubs for sbi_console_putchar/getchar()

[Anup Patel]

The functions sbi_console_putchar() and sbi_console_getchar() are
not defined when CONFIG_RISCV_SBI_V01 is disabled so let us add
stub of these functions to avoid "#ifdef" on user side.

Signed-off-by: Anup Patel <apatel@ventanamicro.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
---
 arch/riscv/include/asm/sbi.h | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/arch/riscv/include/asm/sbi.h b/arch/riscv/include/asm/sbi.h
index 12dfda6bb924..cbcefa344417 100644
--- a/arch/riscv/include/asm/sbi.h
+++ b/arch/riscv/include/asm/sbi.h
@@ -271,8 +271,13 @@ struct sbiret sbi_ecall(int ext, int fid, unsigned long arg0,
 			unsigned long arg3, unsigned long arg4,
 			unsigned long arg5);
 
+#ifdef CONFIG_RISCV_SBI_V01
 void sbi_console_putchar(int ch);
 int sbi_console_getchar(void);
+#else
+static inline void sbi_console_putchar(int ch) { }
+static inline int sbi_console_getchar(void) { return -1; }
+#endif
 long sbi_get_mvendorid(void);
 long sbi_get_marchid(void);
 long sbi_get_mimpid(void);
-- 
2.34.1

Re: [PATCH v3 6/9] RISC-V: Add stubs for sbi_console_putchar/getchar()

[Greg Kroah-Hartman]

On Fri, Oct 20, 2023 at 12:51:37PM +0530, Anup Patel wrote:
> The functions sbi_console_putchar() and sbi_console_getchar() are
> not defined when CONFIG_RISCV_SBI_V01 is disabled so let us add
> stub of these functions to avoid "#ifdef" on user side.
> 
> Signed-off-by: Anup Patel <apatel@ventanamicro.com>
> Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
> ---
>  arch/riscv/include/asm/sbi.h | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/arch/riscv/include/asm/sbi.h b/arch/riscv/include/asm/sbi.h
> index 12dfda6bb924..cbcefa344417 100644
> --- a/arch/riscv/include/asm/sbi.h
> +++ b/arch/riscv/include/asm/sbi.h
> @@ -271,8 +271,13 @@ struct sbiret sbi_ecall(int ext, int fid, unsigned long arg0,
>  			unsigned long arg3, unsigned long arg4,
>  			unsigned long arg5);
>  
> +#ifdef CONFIG_RISCV_SBI_V01
>  void sbi_console_putchar(int ch);
>  int sbi_console_getchar(void);
> +#else
> +static inline void sbi_console_putchar(int ch) { }
> +static inline int sbi_console_getchar(void) { return -1; }

Why not return a real error, "-1" isn't that :)

thanks,

greg k-h

Re: [PATCH v3 6/9] RISC-V: Add stubs for sbi_console_putchar/getchar()

[Anup Patel]

On Sat, Oct 21, 2023 at 10:05 PM Greg Kroah-Hartman
<gregkh@linuxfoundation.org> wrote:
>
> On Fri, Oct 20, 2023 at 12:51:37PM +0530, Anup Patel wrote:
> > The functions sbi_console_putchar() and sbi_console_getchar() are
> > not defined when CONFIG_RISCV_SBI_V01 is disabled so let us add
> > stub of these functions to avoid "#ifdef" on user side.
> >
> > Signed-off-by: Anup Patel <apatel@ventanamicro.com>
> > Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
> > ---
> >  arch/riscv/include/asm/sbi.h | 5 +++++
> >  1 file changed, 5 insertions(+)
> >
> > diff --git a/arch/riscv/include/asm/sbi.h b/arch/riscv/include/asm/sbi.h
> > index 12dfda6bb924..cbcefa344417 100644
> > --- a/arch/riscv/include/asm/sbi.h
> > +++ b/arch/riscv/include/asm/sbi.h
> > @@ -271,8 +271,13 @@ struct sbiret sbi_ecall(int ext, int fid, unsigned long arg0,
> >                       unsigned long arg3, unsigned long arg4,
> >                       unsigned long arg5);
> >
> > +#ifdef CONFIG_RISCV_SBI_V01
> >  void sbi_console_putchar(int ch);
> >  int sbi_console_getchar(void);
> > +#else
> > +static inline void sbi_console_putchar(int ch) { }
> > +static inline int sbi_console_getchar(void) { return -1; }
>
> Why not return a real error, "-1" isn't that :)

As-per SBI spec, the legacy sbi_console_getchar() returns
-1 upon failure hence the code.

Refer, section 5.3 of the latest SBI spec
https://github.com/riscv-non-isa/riscv-sbi-doc/releases/download/commit-fe4562532a9cc57e5743b6466946c5e5c98c73ca/riscv-sbi.pdf

Although, the users of this function only expect a negative
value upon failure so better to return proper error code here.

I will update.

>
> thanks,
>
> greg k-h
>
> --
> kvm-riscv mailing list
> kvm-riscv@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/kvm-riscv

Regards,
Anup

[PATCH v3 7/9] tty/serial: Add RISC-V SBI debug console based earlycon

[Anup Patel]

We extend the existing RISC-V SBI earlycon support to use the new
RISC-V SBI debug console extension.

Signed-off-by: Anup Patel <apatel@ventanamicro.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
---
 drivers/tty/serial/Kconfig              |  2 +-
 drivers/tty/serial/earlycon-riscv-sbi.c | 32 +++++++++++++++++++++----
 2 files changed, 29 insertions(+), 5 deletions(-)

diff --git a/drivers/tty/serial/Kconfig b/drivers/tty/serial/Kconfig
index bdc568a4ab66..cec46091a716 100644
--- a/drivers/tty/serial/Kconfig
+++ b/drivers/tty/serial/Kconfig
@@ -87,7 +87,7 @@ config SERIAL_EARLYCON_SEMIHOST
 
 config SERIAL_EARLYCON_RISCV_SBI
 	bool "Early console using RISC-V SBI"
-	depends on RISCV_SBI_V01
+	depends on RISCV_SBI
 	select SERIAL_CORE
 	select SERIAL_CORE_CONSOLE
 	select SERIAL_EARLYCON
diff --git a/drivers/tty/serial/earlycon-riscv-sbi.c b/drivers/tty/serial/earlycon-riscv-sbi.c
index 27afb0b74ea7..c21cdef254e7 100644
--- a/drivers/tty/serial/earlycon-riscv-sbi.c
+++ b/drivers/tty/serial/earlycon-riscv-sbi.c
@@ -15,17 +15,41 @@ static void sbi_putc(struct uart_port *port, unsigned char c)
 	sbi_console_putchar(c);
 }
 
-static void sbi_console_write(struct console *con,
-			      const char *s, unsigned n)
+static void sbi_0_1_console_write(struct console *con,
+				  const char *s, unsigned int n)
 {
 	struct earlycon_device *dev = con->data;
 	uart_console_write(&dev->port, s, n, sbi_putc);
 }
 
+static void sbi_dbcn_console_write(struct console *con,
+				   const char *s, unsigned int n)
+{
+	phys_addr_t pa = __pa(s);
+
+	if (IS_ENABLED(CONFIG_32BIT))
+		sbi_ecall(SBI_EXT_DBCN, SBI_EXT_DBCN_CONSOLE_WRITE,
+			  n, lower_32_bits(pa), upper_32_bits(pa), 0, 0, 0);
+	else
+		sbi_ecall(SBI_EXT_DBCN, SBI_EXT_DBCN_CONSOLE_WRITE,
+			  n, pa, 0, 0, 0, 0);
+}
+
 static int __init early_sbi_setup(struct earlycon_device *device,
 				  const char *opt)
 {
-	device->con->write = sbi_console_write;
-	return 0;
+	int ret = 0;
+
+	if ((sbi_spec_version >= sbi_mk_version(2, 0)) &&
+	    (sbi_probe_extension(SBI_EXT_DBCN) > 0)) {
+		device->con->write = sbi_dbcn_console_write;
+	} else {
+		if (IS_ENABLED(CONFIG_RISCV_SBI_V01))
+			device->con->write = sbi_0_1_console_write;
+		else
+			ret = -ENODEV;
+	}
+
+	return ret;
 }
 EARLYCON_DECLARE(sbi, early_sbi_setup);
-- 
2.34.1

Re: [PATCH v3 7/9] tty/serial: Add RISC-V SBI debug console based earlycon

[Greg Kroah-Hartman]

On Fri, Oct 20, 2023 at 12:51:38PM +0530, Anup Patel wrote:
> We extend the existing RISC-V SBI earlycon support to use the new
> RISC-V SBI debug console extension.
> 
> Signed-off-by: Anup Patel <apatel@ventanamicro.com>
> Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
> ---
>  drivers/tty/serial/Kconfig              |  2 +-
>  drivers/tty/serial/earlycon-riscv-sbi.c | 32 +++++++++++++++++++++----
>  2 files changed, 29 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/tty/serial/Kconfig b/drivers/tty/serial/Kconfig
> index bdc568a4ab66..cec46091a716 100644
> --- a/drivers/tty/serial/Kconfig
> +++ b/drivers/tty/serial/Kconfig
> @@ -87,7 +87,7 @@ config SERIAL_EARLYCON_SEMIHOST
>  
>  config SERIAL_EARLYCON_RISCV_SBI
>  	bool "Early console using RISC-V SBI"
> -	depends on RISCV_SBI_V01
> +	depends on RISCV_SBI
>  	select SERIAL_CORE
>  	select SERIAL_CORE_CONSOLE
>  	select SERIAL_EARLYCON
> diff --git a/drivers/tty/serial/earlycon-riscv-sbi.c b/drivers/tty/serial/earlycon-riscv-sbi.c
> index 27afb0b74ea7..c21cdef254e7 100644
> --- a/drivers/tty/serial/earlycon-riscv-sbi.c
> +++ b/drivers/tty/serial/earlycon-riscv-sbi.c
> @@ -15,17 +15,41 @@ static void sbi_putc(struct uart_port *port, unsigned char c)
>  	sbi_console_putchar(c);
>  }
>  
> -static void sbi_console_write(struct console *con,
> -			      const char *s, unsigned n)
> +static void sbi_0_1_console_write(struct console *con,
> +				  const char *s, unsigned int n)
>  {
>  	struct earlycon_device *dev = con->data;
>  	uart_console_write(&dev->port, s, n, sbi_putc);
>  }
>  
> +static void sbi_dbcn_console_write(struct console *con,
> +				   const char *s, unsigned int n)
> +{
> +	phys_addr_t pa = __pa(s);
> +
> +	if (IS_ENABLED(CONFIG_32BIT))
> +		sbi_ecall(SBI_EXT_DBCN, SBI_EXT_DBCN_CONSOLE_WRITE,
> +			  n, lower_32_bits(pa), upper_32_bits(pa), 0, 0, 0);
> +	else
> +		sbi_ecall(SBI_EXT_DBCN, SBI_EXT_DBCN_CONSOLE_WRITE,
> +			  n, pa, 0, 0, 0, 0);

This is still a bit hard to follow, and I guarantee it will be a pain to
maintain over time, trying to keep both calls in sync, right?

Why not fix up sbi_ecall() to get this correct instead?  It should be
handling phys_addr_t values, not forcing you to do odd bit masking every
single time you call it, right?  That would make things much easier
overall, and this patch simpler, as well as the next one.

Oh wait, sbi_ecall() is crazy, and just a pass-through, so that's not
going to work, you need a wrapper function for this mess to do that bit
twiddeling for you instead of forcing you to do it each time, I guess
that's what you are trying to do here, but ick, is it correct?

thanks,

greg k-h

Re: [PATCH v3 7/9] tty/serial: Add RISC-V SBI debug console based earlycon

[Anup Patel]

On Sat, Oct 21, 2023 at 10:16 PM Greg Kroah-Hartman
<gregkh@linuxfoundation.org> wrote:
>
> On Fri, Oct 20, 2023 at 12:51:38PM +0530, Anup Patel wrote:
> > We extend the existing RISC-V SBI earlycon support to use the new
> > RISC-V SBI debug console extension.
> >
> > Signed-off-by: Anup Patel <apatel@ventanamicro.com>
> > Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
> > ---
> >  drivers/tty/serial/Kconfig              |  2 +-
> >  drivers/tty/serial/earlycon-riscv-sbi.c | 32 +++++++++++++++++++++----
> >  2 files changed, 29 insertions(+), 5 deletions(-)
> >
> > diff --git a/drivers/tty/serial/Kconfig b/drivers/tty/serial/Kconfig
> > index bdc568a4ab66..cec46091a716 100644
> > --- a/drivers/tty/serial/Kconfig
> > +++ b/drivers/tty/serial/Kconfig
> > @@ -87,7 +87,7 @@ config SERIAL_EARLYCON_SEMIHOST
> >
> >  config SERIAL_EARLYCON_RISCV_SBI
> >       bool "Early console using RISC-V SBI"
> > -     depends on RISCV_SBI_V01
> > +     depends on RISCV_SBI
> >       select SERIAL_CORE
> >       select SERIAL_CORE_CONSOLE
> >       select SERIAL_EARLYCON
> > diff --git a/drivers/tty/serial/earlycon-riscv-sbi.c b/drivers/tty/serial/earlycon-riscv-sbi.c
> > index 27afb0b74ea7..c21cdef254e7 100644
> > --- a/drivers/tty/serial/earlycon-riscv-sbi.c
> > +++ b/drivers/tty/serial/earlycon-riscv-sbi.c
> > @@ -15,17 +15,41 @@ static void sbi_putc(struct uart_port *port, unsigned char c)
> >       sbi_console_putchar(c);
> >  }
> >
> > -static void sbi_console_write(struct console *con,
> > -                           const char *s, unsigned n)
> > +static void sbi_0_1_console_write(struct console *con,
> > +                               const char *s, unsigned int n)
> >  {
> >       struct earlycon_device *dev = con->data;
> >       uart_console_write(&dev->port, s, n, sbi_putc);
> >  }
> >
> > +static void sbi_dbcn_console_write(struct console *con,
> > +                                const char *s, unsigned int n)
> > +{
> > +     phys_addr_t pa = __pa(s);
> > +
> > +     if (IS_ENABLED(CONFIG_32BIT))
> > +             sbi_ecall(SBI_EXT_DBCN, SBI_EXT_DBCN_CONSOLE_WRITE,
> > +                       n, lower_32_bits(pa), upper_32_bits(pa), 0, 0, 0);
> > +     else
> > +             sbi_ecall(SBI_EXT_DBCN, SBI_EXT_DBCN_CONSOLE_WRITE,
> > +                       n, pa, 0, 0, 0, 0);
>
> This is still a bit hard to follow, and I guarantee it will be a pain to
> maintain over time, trying to keep both calls in sync, right?
>
> Why not fix up sbi_ecall() to get this correct instead?  It should be
> handling phys_addr_t values, not forcing you to do odd bit masking every
> single time you call it, right?  That would make things much easier
> overall, and this patch simpler, as well as the next one.

On RV32 systems, the physical address can be 34bits wide hence
the on RV32 we have to pass physical address as two parameters
whereas on RV64 entier physical address can be passed as single
parameter.

>
> Oh wait, sbi_ecall() is crazy, and just a pass-through, so that's not
> going to work, you need a wrapper function for this mess to do that bit
> twiddeling for you instead of forcing you to do it each time, I guess
> that's what you are trying to do here, but ick, is it correct?

Yes, it is better to have a wrapper function to hide the differences
of RV32 and RV64 systems. I will update.

>
> thanks,
>
> greg k-h
>
> --
> kvm-riscv mailing list
> kvm-riscv@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/kvm-riscv

Regards,
Anup

[PATCH v3 8/9] tty: Add SBI debug console support to HVC SBI driver

[Anup Patel]

From: Atish Patra <atishp@rivosinc.com>

RISC-V SBI specification supports advanced debug console
support via SBI DBCN extension.

Extend the HVC SBI driver to support it.

Signed-off-by: Atish Patra <atishp@rivosinc.com>
Signed-off-by: Anup Patel <apatel@ventanamicro.com>
---
 drivers/tty/hvc/Kconfig         |  2 +-
 drivers/tty/hvc/hvc_riscv_sbi.c | 82 ++++++++++++++++++++++++++++++---
 2 files changed, 76 insertions(+), 8 deletions(-)

diff --git a/drivers/tty/hvc/Kconfig b/drivers/tty/hvc/Kconfig
index 4f9264d005c0..6e05c5c7bca1 100644
--- a/drivers/tty/hvc/Kconfig
+++ b/drivers/tty/hvc/Kconfig
@@ -108,7 +108,7 @@ config HVC_DCC_SERIALIZE_SMP
 
 config HVC_RISCV_SBI
 	bool "RISC-V SBI console support"
-	depends on RISCV_SBI_V01
+	depends on RISCV_SBI
 	select HVC_DRIVER
 	help
 	  This enables support for console output via RISC-V SBI calls, which
diff --git a/drivers/tty/hvc/hvc_riscv_sbi.c b/drivers/tty/hvc/hvc_riscv_sbi.c
index 31f53fa77e4a..56da1a4b5aca 100644
--- a/drivers/tty/hvc/hvc_riscv_sbi.c
+++ b/drivers/tty/hvc/hvc_riscv_sbi.c
@@ -39,21 +39,89 @@ static int hvc_sbi_tty_get(uint32_t vtermno, char *buf, int count)
 	return i;
 }
 
-static const struct hv_ops hvc_sbi_ops = {
+static const struct hv_ops hvc_sbi_v01_ops = {
 	.get_chars = hvc_sbi_tty_get,
 	.put_chars = hvc_sbi_tty_put,
 };
 
-static int __init hvc_sbi_init(void)
+static int hvc_sbi_dbcn_tty_put(uint32_t vtermno, const char *buf, int count)
 {
-	return PTR_ERR_OR_ZERO(hvc_alloc(0, 0, &hvc_sbi_ops, 16));
+	phys_addr_t pa;
+	struct sbiret ret;
+
+	if (is_vmalloc_addr(buf)) {
+		pa = page_to_phys(vmalloc_to_page(buf)) + offset_in_page(buf);
+		if (PAGE_SIZE < (offset_in_page(buf) + count))
+			count = PAGE_SIZE - offset_in_page(buf);
+	} else {
+		pa = __pa(buf);
+	}
+
+	if (IS_ENABLED(CONFIG_32BIT))
+		ret = sbi_ecall(SBI_EXT_DBCN, SBI_EXT_DBCN_CONSOLE_WRITE,
+				count, lower_32_bits(pa), upper_32_bits(pa),
+				0, 0, 0);
+	else
+		ret = sbi_ecall(SBI_EXT_DBCN, SBI_EXT_DBCN_CONSOLE_WRITE,
+				count, pa, 0, 0, 0, 0);
+	if (ret.error)
+		return 0;
+
+	return count;
 }
-device_initcall(hvc_sbi_init);
 
-static int __init hvc_sbi_console_init(void)
+static int hvc_sbi_dbcn_tty_get(uint32_t vtermno, char *buf, int count)
 {
-	hvc_instantiate(0, 0, &hvc_sbi_ops);
+	phys_addr_t pa;
+	struct sbiret ret;
+
+	if (is_vmalloc_addr(buf)) {
+		pa = page_to_phys(vmalloc_to_page(buf)) + offset_in_page(buf);
+		if (PAGE_SIZE < (offset_in_page(buf) + count))
+			count = PAGE_SIZE - offset_in_page(buf);
+	} else {
+		pa = __pa(buf);
+	}
+
+	if (IS_ENABLED(CONFIG_32BIT))
+		ret = sbi_ecall(SBI_EXT_DBCN, SBI_EXT_DBCN_CONSOLE_READ,
+				count, lower_32_bits(pa), upper_32_bits(pa),
+				0, 0, 0);
+	else
+		ret = sbi_ecall(SBI_EXT_DBCN, SBI_EXT_DBCN_CONSOLE_READ,
+				count, pa, 0, 0, 0, 0);
+	if (ret.error)
+		return 0;
+
+	return ret.value;
+}
+
+static const struct hv_ops hvc_sbi_dbcn_ops = {
+	.put_chars = hvc_sbi_dbcn_tty_put,
+	.get_chars = hvc_sbi_dbcn_tty_get,
+};
+
+static int __init hvc_sbi_init(void)
+{
+	int err;
+
+	if ((sbi_spec_version >= sbi_mk_version(2, 0)) &&
+	    (sbi_probe_extension(SBI_EXT_DBCN) > 0)) {
+		err = PTR_ERR_OR_ZERO(hvc_alloc(0, 0, &hvc_sbi_dbcn_ops, 16));
+		if (err)
+			return err;
+		hvc_instantiate(0, 0, &hvc_sbi_dbcn_ops);
+	} else {
+		if (IS_ENABLED(CONFIG_RISCV_SBI_V01)) {
+			err = PTR_ERR_OR_ZERO(hvc_alloc(0, 0, &hvc_sbi_v01_ops, 16));
+			if (err)
+				return err;
+			hvc_instantiate(0, 0, &hvc_sbi_v01_ops);
+		} else {
+			return -ENODEV;
+		}
+	}
 
 	return 0;
 }
-console_initcall(hvc_sbi_console_init);
+device_initcall(hvc_sbi_init);
-- 
2.34.1

Re: [PATCH v3 8/9] tty: Add SBI debug console support to HVC SBI driver

[Björn Töpel]

Anup Patel <apatel@ventanamicro.com> writes:

> From: Atish Patra <atishp@rivosinc.com>
>
> RISC-V SBI specification supports advanced debug console
> support via SBI DBCN extension.
>
> Extend the HVC SBI driver to support it.
>
> Signed-off-by: Atish Patra <atishp@rivosinc.com>
> Signed-off-by: Anup Patel <apatel@ventanamicro.com>
> ---
>  drivers/tty/hvc/Kconfig         |  2 +-
>  drivers/tty/hvc/hvc_riscv_sbi.c | 82 ++++++++++++++++++++++++++++++---
>  2 files changed, 76 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/tty/hvc/Kconfig b/drivers/tty/hvc/Kconfig
> index 4f9264d005c0..6e05c5c7bca1 100644
> --- a/drivers/tty/hvc/Kconfig
> +++ b/drivers/tty/hvc/Kconfig
> @@ -108,7 +108,7 @@ config HVC_DCC_SERIALIZE_SMP
>  
>  config HVC_RISCV_SBI
>  	bool "RISC-V SBI console support"
> -	depends on RISCV_SBI_V01
> +	depends on RISCV_SBI
>  	select HVC_DRIVER
>  	help
>  	  This enables support for console output via RISC-V SBI calls, which
> diff --git a/drivers/tty/hvc/hvc_riscv_sbi.c b/drivers/tty/hvc/hvc_riscv_sbi.c
> index 31f53fa77e4a..56da1a4b5aca 100644
> --- a/drivers/tty/hvc/hvc_riscv_sbi.c
> +++ b/drivers/tty/hvc/hvc_riscv_sbi.c
> @@ -39,21 +39,89 @@ static int hvc_sbi_tty_get(uint32_t vtermno, char *buf, int count)
>  	return i;
>  }
>  
> -static const struct hv_ops hvc_sbi_ops = {
> +static const struct hv_ops hvc_sbi_v01_ops = {
>  	.get_chars = hvc_sbi_tty_get,
>  	.put_chars = hvc_sbi_tty_put,
>  };
>  
> -static int __init hvc_sbi_init(void)
> +static int hvc_sbi_dbcn_tty_put(uint32_t vtermno, const char *buf, int count)
>  {
> -	return PTR_ERR_OR_ZERO(hvc_alloc(0, 0, &hvc_sbi_ops, 16));
> +	phys_addr_t pa;
> +	struct sbiret ret;
> +
> +	if (is_vmalloc_addr(buf)) {
> +		pa = page_to_phys(vmalloc_to_page(buf)) + offset_in_page(buf);
> +		if (PAGE_SIZE < (offset_in_page(buf) + count))
> +			count = PAGE_SIZE - offset_in_page(buf);

Thanks for fixing the cross-page issue. Now you're cutting the buffer
off. What about doing two SBI calls instead? (Dito on the get side)


Björn

Re: [PATCH v3 8/9] tty: Add SBI debug console support to HVC SBI driver

[Anup Patel]

On Fri, Oct 20, 2023 at 3:25 PM Björn Töpel <bjorn@kernel.org> wrote:
>
> Anup Patel <apatel@ventanamicro.com> writes:
>
> > From: Atish Patra <atishp@rivosinc.com>
> >
> > RISC-V SBI specification supports advanced debug console
> > support via SBI DBCN extension.
> >
> > Extend the HVC SBI driver to support it.
> >
> > Signed-off-by: Atish Patra <atishp@rivosinc.com>
> > Signed-off-by: Anup Patel <apatel@ventanamicro.com>
> > ---
> >  drivers/tty/hvc/Kconfig         |  2 +-
> >  drivers/tty/hvc/hvc_riscv_sbi.c | 82 ++++++++++++++++++++++++++++++---
> >  2 files changed, 76 insertions(+), 8 deletions(-)
> >
> > diff --git a/drivers/tty/hvc/Kconfig b/drivers/tty/hvc/Kconfig
> > index 4f9264d005c0..6e05c5c7bca1 100644
> > --- a/drivers/tty/hvc/Kconfig
> > +++ b/drivers/tty/hvc/Kconfig
> > @@ -108,7 +108,7 @@ config HVC_DCC_SERIALIZE_SMP
> >
> >  config HVC_RISCV_SBI
> >       bool "RISC-V SBI console support"
> > -     depends on RISCV_SBI_V01
> > +     depends on RISCV_SBI
> >       select HVC_DRIVER
> >       help
> >         This enables support for console output via RISC-V SBI calls, which
> > diff --git a/drivers/tty/hvc/hvc_riscv_sbi.c b/drivers/tty/hvc/hvc_riscv_sbi.c
> > index 31f53fa77e4a..56da1a4b5aca 100644
> > --- a/drivers/tty/hvc/hvc_riscv_sbi.c
> > +++ b/drivers/tty/hvc/hvc_riscv_sbi.c
> > @@ -39,21 +39,89 @@ static int hvc_sbi_tty_get(uint32_t vtermno, char *buf, int count)
> >       return i;
> >  }
> >
> > -static const struct hv_ops hvc_sbi_ops = {
> > +static const struct hv_ops hvc_sbi_v01_ops = {
> >       .get_chars = hvc_sbi_tty_get,
> >       .put_chars = hvc_sbi_tty_put,
> >  };
> >
> > -static int __init hvc_sbi_init(void)
> > +static int hvc_sbi_dbcn_tty_put(uint32_t vtermno, const char *buf, int count)
> >  {
> > -     return PTR_ERR_OR_ZERO(hvc_alloc(0, 0, &hvc_sbi_ops, 16));
> > +     phys_addr_t pa;
> > +     struct sbiret ret;
> > +
> > +     if (is_vmalloc_addr(buf)) {
> > +             pa = page_to_phys(vmalloc_to_page(buf)) + offset_in_page(buf);
> > +             if (PAGE_SIZE < (offset_in_page(buf) + count))
> > +                     count = PAGE_SIZE - offset_in_page(buf);
>
> Thanks for fixing the cross-page issue. Now you're cutting the buffer
> off. What about doing two SBI calls instead? (Dito on the get side)

We don't need to handle that because the hvc_console framework
will ensure remaining characters are sent-out. Same applies to
get side as well.

Regards,
Anup

Re: [PATCH v3 8/9] tty: Add SBI debug console support to HVC SBI driver

[Andrew Jones]

On Fri, Oct 20, 2023 at 12:51:39PM +0530, Anup Patel wrote:
> From: Atish Patra <atishp@rivosinc.com>
> 
> RISC-V SBI specification supports advanced debug console
> support via SBI DBCN extension.
> 
> Extend the HVC SBI driver to support it.
> 
> Signed-off-by: Atish Patra <atishp@rivosinc.com>
> Signed-off-by: Anup Patel <apatel@ventanamicro.com>
> ---
>  drivers/tty/hvc/Kconfig         |  2 +-
>  drivers/tty/hvc/hvc_riscv_sbi.c | 82 ++++++++++++++++++++++++++++++---
>  2 files changed, 76 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/tty/hvc/Kconfig b/drivers/tty/hvc/Kconfig
> index 4f9264d005c0..6e05c5c7bca1 100644
> --- a/drivers/tty/hvc/Kconfig
> +++ b/drivers/tty/hvc/Kconfig
> @@ -108,7 +108,7 @@ config HVC_DCC_SERIALIZE_SMP
>  
>  config HVC_RISCV_SBI
>  	bool "RISC-V SBI console support"
> -	depends on RISCV_SBI_V01
> +	depends on RISCV_SBI
>  	select HVC_DRIVER
>  	help
>  	  This enables support for console output via RISC-V SBI calls, which
> diff --git a/drivers/tty/hvc/hvc_riscv_sbi.c b/drivers/tty/hvc/hvc_riscv_sbi.c
> index 31f53fa77e4a..56da1a4b5aca 100644
> --- a/drivers/tty/hvc/hvc_riscv_sbi.c
> +++ b/drivers/tty/hvc/hvc_riscv_sbi.c
> @@ -39,21 +39,89 @@ static int hvc_sbi_tty_get(uint32_t vtermno, char *buf, int count)
>  	return i;
>  }
>  
> -static const struct hv_ops hvc_sbi_ops = {
> +static const struct hv_ops hvc_sbi_v01_ops = {
>  	.get_chars = hvc_sbi_tty_get,
>  	.put_chars = hvc_sbi_tty_put,
>  };
>  
> -static int __init hvc_sbi_init(void)
> +static int hvc_sbi_dbcn_tty_put(uint32_t vtermno, const char *buf, int count)
>  {
> -	return PTR_ERR_OR_ZERO(hvc_alloc(0, 0, &hvc_sbi_ops, 16));
> +	phys_addr_t pa;
> +	struct sbiret ret;
> +
> +	if (is_vmalloc_addr(buf)) {
> +		pa = page_to_phys(vmalloc_to_page(buf)) + offset_in_page(buf);
> +		if (PAGE_SIZE < (offset_in_page(buf) + count))

I thought checkpatch complained about uppercase constants being on the
left in comparisons.

> +			count = PAGE_SIZE - offset_in_page(buf);
> +	} else {
> +		pa = __pa(buf);
> +	}
> +
> +	if (IS_ENABLED(CONFIG_32BIT))
> +		ret = sbi_ecall(SBI_EXT_DBCN, SBI_EXT_DBCN_CONSOLE_WRITE,
> +				count, lower_32_bits(pa), upper_32_bits(pa),
> +				0, 0, 0);
> +	else
> +		ret = sbi_ecall(SBI_EXT_DBCN, SBI_EXT_DBCN_CONSOLE_WRITE,
> +				count, pa, 0, 0, 0, 0);
> +	if (ret.error)
> +		return 0;
> +
> +	return count;

Shouldn't we return ret.value here in case it's less than count? I see we
already do that below in get().

>  }
> -device_initcall(hvc_sbi_init);
>  
> -static int __init hvc_sbi_console_init(void)
> +static int hvc_sbi_dbcn_tty_get(uint32_t vtermno, char *buf, int count)
>  {
> -	hvc_instantiate(0, 0, &hvc_sbi_ops);
> +	phys_addr_t pa;
> +	struct sbiret ret;
> +
> +	if (is_vmalloc_addr(buf)) {
> +		pa = page_to_phys(vmalloc_to_page(buf)) + offset_in_page(buf);
> +		if (PAGE_SIZE < (offset_in_page(buf) + count))
> +			count = PAGE_SIZE - offset_in_page(buf);
> +	} else {
> +		pa = __pa(buf);
> +	}
> +
> +	if (IS_ENABLED(CONFIG_32BIT))
> +		ret = sbi_ecall(SBI_EXT_DBCN, SBI_EXT_DBCN_CONSOLE_READ,
> +				count, lower_32_bits(pa), upper_32_bits(pa),
> +				0, 0, 0);
> +	else
> +		ret = sbi_ecall(SBI_EXT_DBCN, SBI_EXT_DBCN_CONSOLE_READ,
> +				count, pa, 0, 0, 0, 0);
> +	if (ret.error)
> +		return 0;
> +
> +	return ret.value;
> +}
> +
> +static const struct hv_ops hvc_sbi_dbcn_ops = {
> +	.put_chars = hvc_sbi_dbcn_tty_put,
> +	.get_chars = hvc_sbi_dbcn_tty_get,
> +};
> +
> +static int __init hvc_sbi_init(void)
> +{
> +	int err;
> +
> +	if ((sbi_spec_version >= sbi_mk_version(2, 0)) &&
> +	    (sbi_probe_extension(SBI_EXT_DBCN) > 0)) {
> +		err = PTR_ERR_OR_ZERO(hvc_alloc(0, 0, &hvc_sbi_dbcn_ops, 16));

Why an outbuf size of only 16?

> +		if (err)
> +			return err;
> +		hvc_instantiate(0, 0, &hvc_sbi_dbcn_ops);
> +	} else {
> +		if (IS_ENABLED(CONFIG_RISCV_SBI_V01)) {
> +			err = PTR_ERR_OR_ZERO(hvc_alloc(0, 0, &hvc_sbi_v01_ops, 16));
> +			if (err)
> +				return err;
> +			hvc_instantiate(0, 0, &hvc_sbi_v01_ops);
> +		} else {
> +			return -ENODEV;
> +		}
> +	}
>  
>  	return 0;
>  }
> -console_initcall(hvc_sbi_console_init);
> +device_initcall(hvc_sbi_init);
> -- 
> 2.34.1
>

Thanks,
drew

Re: [PATCH v3 8/9] tty: Add SBI debug console support to HVC SBI driver

[Anup Patel]

On Fri, Oct 20, 2023 at 4:16 PM Andrew Jones <ajones@ventanamicro.com> wrote:
>
> On Fri, Oct 20, 2023 at 12:51:39PM +0530, Anup Patel wrote:
> > From: Atish Patra <atishp@rivosinc.com>
> >
> > RISC-V SBI specification supports advanced debug console
> > support via SBI DBCN extension.
> >
> > Extend the HVC SBI driver to support it.
> >
> > Signed-off-by: Atish Patra <atishp@rivosinc.com>
> > Signed-off-by: Anup Patel <apatel@ventanamicro.com>
> > ---
> >  drivers/tty/hvc/Kconfig         |  2 +-
> >  drivers/tty/hvc/hvc_riscv_sbi.c | 82 ++++++++++++++++++++++++++++++---
> >  2 files changed, 76 insertions(+), 8 deletions(-)
> >
> > diff --git a/drivers/tty/hvc/Kconfig b/drivers/tty/hvc/Kconfig
> > index 4f9264d005c0..6e05c5c7bca1 100644
> > --- a/drivers/tty/hvc/Kconfig
> > +++ b/drivers/tty/hvc/Kconfig
> > @@ -108,7 +108,7 @@ config HVC_DCC_SERIALIZE_SMP
> >
> >  config HVC_RISCV_SBI
> >       bool "RISC-V SBI console support"
> > -     depends on RISCV_SBI_V01
> > +     depends on RISCV_SBI
> >       select HVC_DRIVER
> >       help
> >         This enables support for console output via RISC-V SBI calls, which
> > diff --git a/drivers/tty/hvc/hvc_riscv_sbi.c b/drivers/tty/hvc/hvc_riscv_sbi.c
> > index 31f53fa77e4a..56da1a4b5aca 100644
> > --- a/drivers/tty/hvc/hvc_riscv_sbi.c
> > +++ b/drivers/tty/hvc/hvc_riscv_sbi.c
> > @@ -39,21 +39,89 @@ static int hvc_sbi_tty_get(uint32_t vtermno, char *buf, int count)
> >       return i;
> >  }
> >
> > -static const struct hv_ops hvc_sbi_ops = {
> > +static const struct hv_ops hvc_sbi_v01_ops = {
> >       .get_chars = hvc_sbi_tty_get,
> >       .put_chars = hvc_sbi_tty_put,
> >  };
> >
> > -static int __init hvc_sbi_init(void)
> > +static int hvc_sbi_dbcn_tty_put(uint32_t vtermno, const char *buf, int count)
> >  {
> > -     return PTR_ERR_OR_ZERO(hvc_alloc(0, 0, &hvc_sbi_ops, 16));
> > +     phys_addr_t pa;
> > +     struct sbiret ret;
> > +
> > +     if (is_vmalloc_addr(buf)) {
> > +             pa = page_to_phys(vmalloc_to_page(buf)) + offset_in_page(buf);
> > +             if (PAGE_SIZE < (offset_in_page(buf) + count))
>
> I thought checkpatch complained about uppercase constants being on the
> left in comparisons.

Nope checkpatch does not complain about this.

>
> > +                     count = PAGE_SIZE - offset_in_page(buf);
> > +     } else {
> > +             pa = __pa(buf);
> > +     }
> > +
> > +     if (IS_ENABLED(CONFIG_32BIT))
> > +             ret = sbi_ecall(SBI_EXT_DBCN, SBI_EXT_DBCN_CONSOLE_WRITE,
> > +                             count, lower_32_bits(pa), upper_32_bits(pa),
> > +                             0, 0, 0);
> > +     else
> > +             ret = sbi_ecall(SBI_EXT_DBCN, SBI_EXT_DBCN_CONSOLE_WRITE,
> > +                             count, pa, 0, 0, 0, 0);
> > +     if (ret.error)
> > +             return 0;
> > +
> > +     return count;
>
> Shouldn't we return ret.value here in case it's less than count? I see we
> already do that below in get().

Ahh, yes. Good catch, I will update.

>
> >  }
> > -device_initcall(hvc_sbi_init);
> >
> > -static int __init hvc_sbi_console_init(void)
> > +static int hvc_sbi_dbcn_tty_get(uint32_t vtermno, char *buf, int count)
> >  {
> > -     hvc_instantiate(0, 0, &hvc_sbi_ops);
> > +     phys_addr_t pa;
> > +     struct sbiret ret;
> > +
> > +     if (is_vmalloc_addr(buf)) {
> > +             pa = page_to_phys(vmalloc_to_page(buf)) + offset_in_page(buf);
> > +             if (PAGE_SIZE < (offset_in_page(buf) + count))
> > +                     count = PAGE_SIZE - offset_in_page(buf);
> > +     } else {
> > +             pa = __pa(buf);
> > +     }
> > +
> > +     if (IS_ENABLED(CONFIG_32BIT))
> > +             ret = sbi_ecall(SBI_EXT_DBCN, SBI_EXT_DBCN_CONSOLE_READ,
> > +                             count, lower_32_bits(pa), upper_32_bits(pa),
> > +                             0, 0, 0);
> > +     else
> > +             ret = sbi_ecall(SBI_EXT_DBCN, SBI_EXT_DBCN_CONSOLE_READ,
> > +                             count, pa, 0, 0, 0, 0);
> > +     if (ret.error)
> > +             return 0;
> > +
> > +     return ret.value;
> > +}
> > +
> > +static const struct hv_ops hvc_sbi_dbcn_ops = {
> > +     .put_chars = hvc_sbi_dbcn_tty_put,
> > +     .get_chars = hvc_sbi_dbcn_tty_get,
> > +};
> > +
> > +static int __init hvc_sbi_init(void)
> > +{
> > +     int err;
> > +
> > +     if ((sbi_spec_version >= sbi_mk_version(2, 0)) &&
> > +         (sbi_probe_extension(SBI_EXT_DBCN) > 0)) {
> > +             err = PTR_ERR_OR_ZERO(hvc_alloc(0, 0, &hvc_sbi_dbcn_ops, 16));
>
> Why an outbuf size of only 16?

The output buffer size of 16 is a very common choice across
HVC drivers. The next best choice is 256.

I guess 256 is better so I will go with that.

>
> > +             if (err)
> > +                     return err;
> > +             hvc_instantiate(0, 0, &hvc_sbi_dbcn_ops);
> > +     } else {
> > +             if (IS_ENABLED(CONFIG_RISCV_SBI_V01)) {
> > +                     err = PTR_ERR_OR_ZERO(hvc_alloc(0, 0, &hvc_sbi_v01_ops, 16));
> > +                     if (err)
> > +                             return err;
> > +                     hvc_instantiate(0, 0, &hvc_sbi_v01_ops);
> > +             } else {
> > +                     return -ENODEV;
> > +             }
> > +     }
> >
> >       return 0;
> >  }
> > -console_initcall(hvc_sbi_console_init);
> > +device_initcall(hvc_sbi_init);
> > --
> > 2.34.1
> >
>
> Thanks,
> drew

Regards,
Anup

Re: [PATCH v3 8/9] tty: Add SBI debug console support to HVC SBI driver

[Greg Kroah-Hartman]

On Fri, Oct 20, 2023 at 12:51:39PM +0530, Anup Patel wrote:
> From: Atish Patra <atishp@rivosinc.com>
> 
> RISC-V SBI specification supports advanced debug console
> support via SBI DBCN extension.
> 
> Extend the HVC SBI driver to support it.
> 
> Signed-off-by: Atish Patra <atishp@rivosinc.com>
> Signed-off-by: Anup Patel <apatel@ventanamicro.com>
> ---
>  drivers/tty/hvc/Kconfig         |  2 +-
>  drivers/tty/hvc/hvc_riscv_sbi.c | 82 ++++++++++++++++++++++++++++++---
>  2 files changed, 76 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/tty/hvc/Kconfig b/drivers/tty/hvc/Kconfig
> index 4f9264d005c0..6e05c5c7bca1 100644
> --- a/drivers/tty/hvc/Kconfig
> +++ b/drivers/tty/hvc/Kconfig
> @@ -108,7 +108,7 @@ config HVC_DCC_SERIALIZE_SMP
>  
>  config HVC_RISCV_SBI
>  	bool "RISC-V SBI console support"
> -	depends on RISCV_SBI_V01
> +	depends on RISCV_SBI
>  	select HVC_DRIVER
>  	help
>  	  This enables support for console output via RISC-V SBI calls, which
> diff --git a/drivers/tty/hvc/hvc_riscv_sbi.c b/drivers/tty/hvc/hvc_riscv_sbi.c
> index 31f53fa77e4a..56da1a4b5aca 100644
> --- a/drivers/tty/hvc/hvc_riscv_sbi.c
> +++ b/drivers/tty/hvc/hvc_riscv_sbi.c
> @@ -39,21 +39,89 @@ static int hvc_sbi_tty_get(uint32_t vtermno, char *buf, int count)
>  	return i;
>  }
>  
> -static const struct hv_ops hvc_sbi_ops = {
> +static const struct hv_ops hvc_sbi_v01_ops = {
>  	.get_chars = hvc_sbi_tty_get,
>  	.put_chars = hvc_sbi_tty_put,
>  };
>  
> -static int __init hvc_sbi_init(void)
> +static int hvc_sbi_dbcn_tty_put(uint32_t vtermno, const char *buf, int count)
>  {
> -	return PTR_ERR_OR_ZERO(hvc_alloc(0, 0, &hvc_sbi_ops, 16));
> +	phys_addr_t pa;
> +	struct sbiret ret;
> +
> +	if (is_vmalloc_addr(buf)) {
> +		pa = page_to_phys(vmalloc_to_page(buf)) + offset_in_page(buf);
> +		if (PAGE_SIZE < (offset_in_page(buf) + count))
> +			count = PAGE_SIZE - offset_in_page(buf);
> +	} else {
> +		pa = __pa(buf);
> +	}
> +
> +	if (IS_ENABLED(CONFIG_32BIT))
> +		ret = sbi_ecall(SBI_EXT_DBCN, SBI_EXT_DBCN_CONSOLE_WRITE,
> +				count, lower_32_bits(pa), upper_32_bits(pa),
> +				0, 0, 0);
> +	else
> +		ret = sbi_ecall(SBI_EXT_DBCN, SBI_EXT_DBCN_CONSOLE_WRITE,
> +				count, pa, 0, 0, 0, 0);

Again, you need a helper function here to keep you from having to keep
this all in sync.

> +	if (ret.error)
> +		return 0;
> +
> +	return count;
>  }
> -device_initcall(hvc_sbi_init);
>  
> -static int __init hvc_sbi_console_init(void)
> +static int hvc_sbi_dbcn_tty_get(uint32_t vtermno, char *buf, int count)
>  {
> -	hvc_instantiate(0, 0, &hvc_sbi_ops);
> +	phys_addr_t pa;
> +	struct sbiret ret;
> +
> +	if (is_vmalloc_addr(buf)) {
> +		pa = page_to_phys(vmalloc_to_page(buf)) + offset_in_page(buf);
> +		if (PAGE_SIZE < (offset_in_page(buf) + count))
> +			count = PAGE_SIZE - offset_in_page(buf);
> +	} else {
> +		pa = __pa(buf);
> +	}
> +
> +	if (IS_ENABLED(CONFIG_32BIT))
> +		ret = sbi_ecall(SBI_EXT_DBCN, SBI_EXT_DBCN_CONSOLE_READ,
> +				count, lower_32_bits(pa), upper_32_bits(pa),
> +				0, 0, 0);
> +	else
> +		ret = sbi_ecall(SBI_EXT_DBCN, SBI_EXT_DBCN_CONSOLE_READ,
> +				count, pa, 0, 0, 0, 0);

And here too.

thanks,

greg k-h

Re: [PATCH v3 8/9] tty: Add SBI debug console support to HVC SBI driver

[Anup Patel]

On Sat, Oct 21, 2023 at 10:16 PM Greg Kroah-Hartman
<gregkh@linuxfoundation.org> wrote:
>
> On Fri, Oct 20, 2023 at 12:51:39PM +0530, Anup Patel wrote:
> > From: Atish Patra <atishp@rivosinc.com>
> >
> > RISC-V SBI specification supports advanced debug console
> > support via SBI DBCN extension.
> >
> > Extend the HVC SBI driver to support it.
> >
> > Signed-off-by: Atish Patra <atishp@rivosinc.com>
> > Signed-off-by: Anup Patel <apatel@ventanamicro.com>
> > ---
> >  drivers/tty/hvc/Kconfig         |  2 +-
> >  drivers/tty/hvc/hvc_riscv_sbi.c | 82 ++++++++++++++++++++++++++++++---
> >  2 files changed, 76 insertions(+), 8 deletions(-)
> >
> > diff --git a/drivers/tty/hvc/Kconfig b/drivers/tty/hvc/Kconfig
> > index 4f9264d005c0..6e05c5c7bca1 100644
> > --- a/drivers/tty/hvc/Kconfig
> > +++ b/drivers/tty/hvc/Kconfig
> > @@ -108,7 +108,7 @@ config HVC_DCC_SERIALIZE_SMP
> >
> >  config HVC_RISCV_SBI
> >       bool "RISC-V SBI console support"
> > -     depends on RISCV_SBI_V01
> > +     depends on RISCV_SBI
> >       select HVC_DRIVER
> >       help
> >         This enables support for console output via RISC-V SBI calls, which
> > diff --git a/drivers/tty/hvc/hvc_riscv_sbi.c b/drivers/tty/hvc/hvc_riscv_sbi.c
> > index 31f53fa77e4a..56da1a4b5aca 100644
> > --- a/drivers/tty/hvc/hvc_riscv_sbi.c
> > +++ b/drivers/tty/hvc/hvc_riscv_sbi.c
> > @@ -39,21 +39,89 @@ static int hvc_sbi_tty_get(uint32_t vtermno, char *buf, int count)
> >       return i;
> >  }
> >
> > -static const struct hv_ops hvc_sbi_ops = {
> > +static const struct hv_ops hvc_sbi_v01_ops = {
> >       .get_chars = hvc_sbi_tty_get,
> >       .put_chars = hvc_sbi_tty_put,
> >  };
> >
> > -static int __init hvc_sbi_init(void)
> > +static int hvc_sbi_dbcn_tty_put(uint32_t vtermno, const char *buf, int count)
> >  {
> > -     return PTR_ERR_OR_ZERO(hvc_alloc(0, 0, &hvc_sbi_ops, 16));
> > +     phys_addr_t pa;
> > +     struct sbiret ret;
> > +
> > +     if (is_vmalloc_addr(buf)) {
> > +             pa = page_to_phys(vmalloc_to_page(buf)) + offset_in_page(buf);
> > +             if (PAGE_SIZE < (offset_in_page(buf) + count))
> > +                     count = PAGE_SIZE - offset_in_page(buf);
> > +     } else {
> > +             pa = __pa(buf);
> > +     }
> > +
> > +     if (IS_ENABLED(CONFIG_32BIT))
> > +             ret = sbi_ecall(SBI_EXT_DBCN, SBI_EXT_DBCN_CONSOLE_WRITE,
> > +                             count, lower_32_bits(pa), upper_32_bits(pa),
> > +                             0, 0, 0);
> > +     else
> > +             ret = sbi_ecall(SBI_EXT_DBCN, SBI_EXT_DBCN_CONSOLE_WRITE,
> > +                             count, pa, 0, 0, 0, 0);
>
> Again, you need a helper function here to keep you from having to keep
> this all in sync.

Sure, I will update.

>
> > +     if (ret.error)
> > +             return 0;
> > +
> > +     return count;
> >  }
> > -device_initcall(hvc_sbi_init);
> >
> > -static int __init hvc_sbi_console_init(void)
> > +static int hvc_sbi_dbcn_tty_get(uint32_t vtermno, char *buf, int count)
> >  {
> > -     hvc_instantiate(0, 0, &hvc_sbi_ops);
> > +     phys_addr_t pa;
> > +     struct sbiret ret;
> > +
> > +     if (is_vmalloc_addr(buf)) {
> > +             pa = page_to_phys(vmalloc_to_page(buf)) + offset_in_page(buf);
> > +             if (PAGE_SIZE < (offset_in_page(buf) + count))
> > +                     count = PAGE_SIZE - offset_in_page(buf);
> > +     } else {
> > +             pa = __pa(buf);
> > +     }
> > +
> > +     if (IS_ENABLED(CONFIG_32BIT))
> > +             ret = sbi_ecall(SBI_EXT_DBCN, SBI_EXT_DBCN_CONSOLE_READ,
> > +                             count, lower_32_bits(pa), upper_32_bits(pa),
> > +                             0, 0, 0);
> > +     else
> > +             ret = sbi_ecall(SBI_EXT_DBCN, SBI_EXT_DBCN_CONSOLE_READ,
> > +                             count, pa, 0, 0, 0, 0);
>
> And here too.

Okay.

>
> thanks,
>
> greg k-h

Regards,
Anup

[PATCH v3 9/9] RISC-V: Enable SBI based earlycon support

[Anup Patel]

Let us enable SBI based earlycon support in defconfigs for both RV32
and RV64 so that "earlycon=sbi" can be used again.

Signed-off-by: Anup Patel <apatel@ventanamicro.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
---
 arch/riscv/configs/defconfig      | 1 +
 arch/riscv/configs/rv32_defconfig | 1 +
 2 files changed, 2 insertions(+)

diff --git a/arch/riscv/configs/defconfig b/arch/riscv/configs/defconfig
index ab86ec3b9eab..f82700da0056 100644
--- a/arch/riscv/configs/defconfig
+++ b/arch/riscv/configs/defconfig
@@ -132,6 +132,7 @@ CONFIG_SERIAL_8250_CONSOLE=y
 CONFIG_SERIAL_8250_DW=y
 CONFIG_SERIAL_OF_PLATFORM=y
 CONFIG_SERIAL_SH_SCI=y
+CONFIG_SERIAL_EARLYCON_RISCV_SBI=y
 CONFIG_VIRTIO_CONSOLE=y
 CONFIG_HW_RANDOM=y
 CONFIG_HW_RANDOM_VIRTIO=y
diff --git a/arch/riscv/configs/rv32_defconfig b/arch/riscv/configs/rv32_defconfig
index 89b601e253a6..5721af39afd1 100644
--- a/arch/riscv/configs/rv32_defconfig
+++ b/arch/riscv/configs/rv32_defconfig
@@ -66,6 +66,7 @@ CONFIG_INPUT_MOUSEDEV=y
 CONFIG_SERIAL_8250=y
 CONFIG_SERIAL_8250_CONSOLE=y
 CONFIG_SERIAL_OF_PLATFORM=y
+CONFIG_SERIAL_EARLYCON_RISCV_SBI=y
 CONFIG_VIRTIO_CONSOLE=y
 CONFIG_HW_RANDOM=y
 CONFIG_HW_RANDOM_VIRTIO=y
-- 
2.34.1

Re: [PATCH v3 0/9] RISC-V SBI debug console extension support

[Anup Patel]

On Fri, Oct 20, 2023 at 12:51 PM Anup Patel <apatel@ventanamicro.com> wrote:
>
> The SBI v2.0 specification is now frozen. The SBI v2.0 specification defines
> SBI debug console (DBCN) extension which replaces the legacy SBI v0.1
> functions sbi_console_putchar() and sbi_console_getchar().
> (Refer v2.0-rc5 at https://github.com/riscv-non-isa/riscv-sbi-doc/releases)
>
> This series adds support for SBI debug console (DBCN) extension in KVM RISC-V
> and Linux RISC-V.
>
> To try these patches with KVM RISC-V, use KVMTOOL from riscv_sbi_dbcn_v1
> branch at: https://github.com/avpatel/kvmtool.git
>
> These patches can also be found in the riscv_sbi_dbcn_v3 branch at:
> https://github.com/avpatel/linux.git
>
> Changes since v2:
>  - Rebased on Linux-6.6-rc5
>  - Handled page-crossing in PATCH7 of v2 series
>  - Addressed Drew's comment in PATCH3 of v2 series
>  - Added new PATCH5 to make get-reg-list test aware of SBI DBCN extension
>
> Changes since v1:
>  - Remove use of #ifdef from PATCH4 and PATCH5 of the v1 series
>  - Improved commit description of PATCH3 in v1 series
>  - Introduced new PATCH3 in this series to allow some SBI extensions
>    (such as SBI DBCN) do to disabled by default so that older KVM user space
>    work fine and newer KVM user space have to explicitly opt-in for emulating
>    SBI DBCN.
>  - Introduced new PATCH5 in this series which adds inline version of
>    sbi_console_getchar() and sbi_console_putchar() for the case where
>    CONFIG_RISCV_SBI_V01 is disabled.
>
> Anup Patel (8):
>   RISC-V: Add defines for SBI debug console extension
>   RISC-V: KVM: Change the SBI specification version to v2.0
>   RISC-V: KVM: Allow some SBI extensions to be disabled by default
>   RISC-V: KVM: Forward SBI DBCN extension to user-space
>   KVM: riscv: selftests: Add SBI DBCN extension to get-reg-list test
>   RISC-V: Add stubs for sbi_console_putchar/getchar()
>   tty/serial: Add RISC-V SBI debug console based earlycon
>   RISC-V: Enable SBI based earlycon support
>
> Atish Patra (1):
>   tty: Add SBI debug console support to HVC SBI driver

Queued PATCH1 to PATCH5 for Linux-6.7

Remaining PATCH6 to PATCH9 are still under review.

Thanks,
Anup

>
>  arch/riscv/configs/defconfig                  |  1 +
>  arch/riscv/configs/rv32_defconfig             |  1 +
>  arch/riscv/include/asm/kvm_vcpu_sbi.h         |  7 +-
>  arch/riscv/include/asm/sbi.h                  | 12 +++
>  arch/riscv/include/uapi/asm/kvm.h             |  1 +
>  arch/riscv/kvm/vcpu.c                         |  6 ++
>  arch/riscv/kvm/vcpu_sbi.c                     | 61 +++++++-------
>  arch/riscv/kvm/vcpu_sbi_replace.c             | 32 ++++++++
>  drivers/tty/hvc/Kconfig                       |  2 +-
>  drivers/tty/hvc/hvc_riscv_sbi.c               | 82 +++++++++++++++++--
>  drivers/tty/serial/Kconfig                    |  2 +-
>  drivers/tty/serial/earlycon-riscv-sbi.c       | 32 +++++++-
>  .../selftests/kvm/riscv/get-reg-list.c        |  2 +
>  13 files changed, 198 insertions(+), 43 deletions(-)
>
> --
> 2.34.1
>
>
> --
> kvm-riscv mailing list
> kvm-riscv@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/kvm-riscv

Re: [PATCH v3 0/9] RISC-V SBI debug console extension support

[patchwork-bot+linux-riscv]

Hello:

This series was applied to riscv/linux.git (fixes)
by Anup Patel <anup@brainfault.org>:

On Fri, 20 Oct 2023 12:51:31 +0530 you wrote:
> The SBI v2.0 specification is now frozen. The SBI v2.0 specification defines
> SBI debug console (DBCN) extension which replaces the legacy SBI v0.1
> functions sbi_console_putchar() and sbi_console_getchar().
> (Refer v2.0-rc5 at https://github.com/riscv-non-isa/riscv-sbi-doc/releases)
> 
> This series adds support for SBI debug console (DBCN) extension in KVM RISC-V
> and Linux RISC-V.
> 
> [...]

Here is the summary with links:
  - [v3,1/9] RISC-V: Add defines for SBI debug console extension
    https://git.kernel.org/riscv/c/dadf7886993c
  - [v3,2/9] RISC-V: KVM: Change the SBI specification version to v2.0
    https://git.kernel.org/riscv/c/b88e87a0a1ec
  - [v3,3/9] RISC-V: KVM: Allow some SBI extensions to be disabled by default
    https://git.kernel.org/riscv/c/56d8a385b605
  - [v3,4/9] RISC-V: KVM: Forward SBI DBCN extension to user-space
    https://git.kernel.org/riscv/c/c667ad229d13
  - [v3,5/9] KVM: riscv: selftests: Add SBI DBCN extension to get-reg-list test
    https://git.kernel.org/riscv/c/d9c00f44e5de
  - [v3,6/9] RISC-V: Add stubs for sbi_console_putchar/getchar()
    (no matching commit)
  - [v3,7/9] tty/serial: Add RISC-V SBI debug console based earlycon
    (no matching commit)
  - [v3,8/9] tty: Add SBI debug console support to HVC SBI driver
    (no matching commit)
  - [v3,9/9] RISC-V: Enable SBI based earlycon support
    (no matching commit)

You are awesome, thank you!
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