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 v2 7/9] RISC-V: KVM: avoid EBUSY when writing the same machine ID val
Date: Tue, 1 Aug 2023 19:26:27 -0300 [thread overview]
Message-ID: <20230801222629.210929-8-dbarboza@ventanamicro.com> (raw)
In-Reply-To: <20230801222629.210929-1-dbarboza@ventanamicro.com>
Right now we do not allow any write in mvendorid/marchid/mimpid if the
vcpu already started, preventing these regs to be changed.
However, if userspace doesn't change them, an alternative is to consider
the reg write a no-op and avoid erroring out altogether. Userpace can
then be oblivious about KVM internals if no changes were intended in the
first place.
Allow the same form of 'lazy writing' that registers such as
zicbom/zicboz_block_size supports: avoid erroring out if userspace makes
no changes in mvendorid/marchid/mimpid during reg write.
Signed-off-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
---
arch/riscv/kvm/vcpu_onereg.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/arch/riscv/kvm/vcpu_onereg.c b/arch/riscv/kvm/vcpu_onereg.c
index b0821f75cc61..1ceccc93ccdb 100644
--- a/arch/riscv/kvm/vcpu_onereg.c
+++ b/arch/riscv/kvm/vcpu_onereg.c
@@ -232,18 +232,24 @@ static int kvm_riscv_vcpu_set_reg_config(struct kvm_vcpu *vcpu,
return -EINVAL;
break;
case KVM_REG_RISCV_CONFIG_REG(mvendorid):
+ if (reg_val == vcpu->arch.mvendorid)
+ break;
if (!vcpu->arch.ran_atleast_once)
vcpu->arch.mvendorid = reg_val;
else
return -EBUSY;
break;
case KVM_REG_RISCV_CONFIG_REG(marchid):
+ if (reg_val == vcpu->arch.marchid)
+ break;
if (!vcpu->arch.ran_atleast_once)
vcpu->arch.marchid = reg_val;
else
return -EBUSY;
break;
case KVM_REG_RISCV_CONFIG_REG(mimpid):
+ if (reg_val == vcpu->arch.mimpid)
+ break;
if (!vcpu->arch.ran_atleast_once)
vcpu->arch.mimpid = reg_val;
else
--
2.41.0
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next prev parent reply other threads:[~2023-08-01 22:27 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-08-01 22:26 [PATCH v2 0/9] RISC-V: KVM: change get_reg/set_reg error codes Daniel Henrique Barboza
2023-08-01 22:26 ` [PATCH v2 1/9] RISC-V: KVM: return ENOENT in *_one_reg() when reg is unknown Daniel Henrique Barboza
2023-08-01 22:26 ` [PATCH v2 2/9] RISC-V: KVM: use ENOENT in *_one_reg() when extension is unavailable Daniel Henrique Barboza
2023-08-01 22:26 ` [PATCH v2 3/9] RISC-V: KVM: do not EOPNOTSUPP in set_one_reg() zicbo(m|z) Daniel Henrique Barboza
2023-08-01 22:26 ` [PATCH v2 4/9] RISC-V: KVM: do not EOPNOTSUPP in set KVM_REG_RISCV_TIMER_REG Daniel Henrique Barboza
2023-08-01 22:26 ` [PATCH v2 5/9] RISC-V: KVM: use EBUSY when !vcpu->arch.ran_atleast_once Daniel Henrique Barboza
2023-08-01 22:26 ` [PATCH v2 6/9] RISC-V: KVM: avoid EBUSY when writing same ISA val Daniel Henrique Barboza
2023-08-01 22:26 ` Daniel Henrique Barboza [this message]
2023-08-01 22:26 ` [PATCH v2 8/9] RISC-V: KVM: avoid EBUSY when writing the same isa_ext val Daniel Henrique Barboza
2023-08-01 22:26 ` [PATCH v2 9/9] docs: kvm: riscv: document EBUSY in KVM_SET_ONE_REG Daniel Henrique Barboza
2023-08-02 8:17 ` Andrew Jones
2023-08-02 9:04 ` [PATCH v2 0/9] RISC-V: KVM: change get_reg/set_reg error codes Andrew Jones
2023-08-02 9:06 ` Andrew Jones
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