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From: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
To: kvm-riscv@lists.infradead.org, linux-riscv@lists.infradead.org,
	kvm@vger.kernel.org
Cc: anup@brainfault.org, atishp@atishpatra.org,
	ajones@ventanamicro.com,
	Daniel Henrique Barboza <dbarboza@ventanamicro.com>
Subject: [PATCH v4 03/10] RISC-V: KVM: do not EOPNOTSUPP in set_one_reg() zicbo(m|z)
Date: Thu,  3 Aug 2023 13:32:55 -0300	[thread overview]
Message-ID: <20230803163302.445167-4-dbarboza@ventanamicro.com> (raw)
In-Reply-To: <20230803163302.445167-1-dbarboza@ventanamicro.com>

zicbom_block_size and zicboz_block_size have a peculiar API: they can be
read via get_one_reg() but any write will return a EOPNOTSUPP.

It makes sense to return a 'not supported' error since both values can't
be changed, but as far as userspace goes they're regs that are throwing
the same EOPNOTSUPP error even if they were read beforehand via
get_one_reg(), even if the same  read value is being written back.
EOPNOTSUPP is also returned even if ZICBOM/ZICBOZ aren't enabled in the
host.

Change both to work more like their counterparts in get_one_reg() and
return -ENOENT if their respective extensions aren't available. After
that, check if the userspace is written a valid value (i.e. the host
value). Throw an -EINVAL if that's not case, let it slide otherwise.

This allows both regs to be read/written by userspace in a 'lazy'
manner, as long as the userspace doesn't change the reg vals.

Suggested-by: Andrew Jones <ajones@ventanamicro.com>
Signed-off-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
---
 arch/riscv/kvm/vcpu_onereg.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/arch/riscv/kvm/vcpu_onereg.c b/arch/riscv/kvm/vcpu_onereg.c
index 1ffd8ac3800a..e06256dd8d24 100644
--- a/arch/riscv/kvm/vcpu_onereg.c
+++ b/arch/riscv/kvm/vcpu_onereg.c
@@ -216,9 +216,17 @@ static int kvm_riscv_vcpu_set_reg_config(struct kvm_vcpu *vcpu,
 		}
 		break;
 	case KVM_REG_RISCV_CONFIG_REG(zicbom_block_size):
-		return -EOPNOTSUPP;
+		if (!riscv_isa_extension_available(vcpu->arch.isa, ZICBOM))
+			return -ENOENT;
+		if (reg_val != riscv_cbom_block_size)
+			return -EINVAL;
+		break;
 	case KVM_REG_RISCV_CONFIG_REG(zicboz_block_size):
-		return -EOPNOTSUPP;
+		if (!riscv_isa_extension_available(vcpu->arch.isa, ZICBOZ))
+			return -ENOENT;
+		if (reg_val != riscv_cboz_block_size)
+			return -EINVAL;
+		break;
 	case KVM_REG_RISCV_CONFIG_REG(mvendorid):
 		if (!vcpu->arch.ran_atleast_once)
 			vcpu->arch.mvendorid = reg_val;
-- 
2.41.0


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  parent reply	other threads:[~2023-08-03 16:33 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-08-03 16:32 [PATCH v4 00/10] RISC-V: KVM: change get_reg/set_reg error code Daniel Henrique Barboza
2023-08-03 16:32 ` [PATCH v4 01/10] RISC-V: KVM: return ENOENT in *_one_reg() when reg is unknown Daniel Henrique Barboza
2023-08-03 16:32 ` [PATCH v4 02/10] RISC-V: KVM: use ENOENT in *_one_reg() when extension is unavailable Daniel Henrique Barboza
2023-08-03 16:32 ` Daniel Henrique Barboza [this message]
2023-08-03 16:32 ` [PATCH v4 04/10] RISC-V: KVM: do not EOPNOTSUPP in set KVM_REG_RISCV_TIMER_REG Daniel Henrique Barboza
2023-08-03 16:32 ` [PATCH v4 05/10] RISC-V: KVM: use EBUSY when !vcpu->arch.ran_atleast_once Daniel Henrique Barboza
2023-08-03 16:32 ` [PATCH v4 06/10] RISC-V: KVM: avoid EBUSY when writing same ISA val Daniel Henrique Barboza
2023-08-03 16:32 ` [PATCH v4 07/10] RISC-V: KVM: avoid EBUSY when writing the same machine ID val Daniel Henrique Barboza
2023-08-03 16:33 ` [PATCH v4 08/10] RISC-V: KVM: avoid EBUSY when writing the same isa_ext val Daniel Henrique Barboza
2023-08-03 16:33 ` [PATCH v4 09/10] RISC-V: KVM: Improve vector save/restore errors Daniel Henrique Barboza
2023-08-03 17:05   ` Andrew Jones
2023-08-03 17:16     ` Andrew Jones
2023-08-03 16:33 ` [PATCH v4 10/10] docs: kvm: riscv: document EBUSY in KVM_SET_ONE_REG Daniel Henrique Barboza
2023-08-03 16:56 ` [PATCH v4 00/10] RISC-V: KVM: change get_reg/set_reg error code Andrew Jones
2023-08-04  9:11 ` Anup Patel
2023-08-05 16:32   ` Anup Patel

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