linux-kernel - [PATCH v2 09/10] RISC-V: KVM: Allow Smnpm and Ssnpm extensions for guests

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Date: Tue, 25 Jun 2024 14:09:20 -0700
From: Samuel Holland <samuel.holland@...ive.com>
To: Palmer Dabbelt <palmer@...belt.com>,
	linux-riscv@...ts.infradead.org
Cc: devicetree@...r.kernel.org,
	Catalin Marinas <catalin.marinas@....com>,
	linux-kernel@...r.kernel.org,
	Anup Patel <anup@...infault.org>,
	Conor Dooley <conor@...nel.org>,
	kasan-dev@...glegroups.com,
	Atish Patra <atishp@...shpatra.org>,
	Evgenii Stepanov <eugenis@...gle.com>,
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
	Rob Herring <robh+dt@...nel.org>,
	"Kirill A . Shutemov" <kirill.shutemov@...ux.intel.com>,
	Samuel Holland <samuel.holland@...ive.com>
Subject: [PATCH v2 09/10] RISC-V: KVM: Allow Smnpm and Ssnpm extensions for guests

The interface for controlling pointer masking in VS-mode is henvcfg.PMM,
which is part of the Ssnpm extension, even though pointer masking in
HS-mode is provided by the Smnpm extension. As a result, emulating Smnpm
in the guest requires (only) Ssnpm on the host.

Since the guest configures Smnpm through the SBI Firmware Features
interface, the extension can be disabled by failing the SBI call. Ssnpm
cannot be disabled without intercepting writes to the senvcfg CSR.

Signed-off-by: Samuel Holland <samuel.holland@...ive.com>
---

Changes in v2:
 - New patch for v2

 arch/riscv/include/uapi/asm/kvm.h | 2 ++
 arch/riscv/kvm/vcpu_onereg.c      | 3 +++
 2 files changed, 5 insertions(+)

diff --git a/arch/riscv/include/uapi/asm/kvm.h b/arch/riscv/include/uapi/asm/kvm.h
index e878e7cc3978..eda2a54c93e3 100644
--- a/arch/riscv/include/uapi/asm/kvm.h
+++ b/arch/riscv/include/uapi/asm/kvm.h
@@ -168,6 +168,8 @@ enum KVM_RISCV_ISA_EXT_ID {
 	KVM_RISCV_ISA_EXT_ZTSO,
 	KVM_RISCV_ISA_EXT_ZACAS,
 	KVM_RISCV_ISA_EXT_SSCOFPMF,
+	KVM_RISCV_ISA_EXT_SMNPM,
+	KVM_RISCV_ISA_EXT_SSNPM,
 	KVM_RISCV_ISA_EXT_MAX,
 };
 
diff --git a/arch/riscv/kvm/vcpu_onereg.c b/arch/riscv/kvm/vcpu_onereg.c
index c676275ea0a0..71c6541d7070 100644
--- a/arch/riscv/kvm/vcpu_onereg.c
+++ b/arch/riscv/kvm/vcpu_onereg.c
@@ -34,9 +34,11 @@ static const unsigned long kvm_isa_ext_arr[] = {
 	[KVM_RISCV_ISA_EXT_M] = RISCV_ISA_EXT_m,
 	[KVM_RISCV_ISA_EXT_V] = RISCV_ISA_EXT_v,
 	/* Multi letter extensions (alphabetically sorted) */
+	[KVM_RISCV_ISA_EXT_SMNPM] = RISCV_ISA_EXT_SSNPM,
 	KVM_ISA_EXT_ARR(SMSTATEEN),
 	KVM_ISA_EXT_ARR(SSAIA),
 	KVM_ISA_EXT_ARR(SSCOFPMF),
+	KVM_ISA_EXT_ARR(SSNPM),
 	KVM_ISA_EXT_ARR(SSTC),
 	KVM_ISA_EXT_ARR(SVINVAL),
 	KVM_ISA_EXT_ARR(SVNAPOT),
@@ -122,6 +124,7 @@ static bool kvm_riscv_vcpu_isa_disable_allowed(unsigned long ext)
 	case KVM_RISCV_ISA_EXT_M:
 	/* There is not architectural config bit to disable sscofpmf completely */
 	case KVM_RISCV_ISA_EXT_SSCOFPMF:
+	case KVM_RISCV_ISA_EXT_SSNPM:
 	case KVM_RISCV_ISA_EXT_SSTC:
 	case KVM_RISCV_ISA_EXT_SVINVAL:
 	case KVM_RISCV_ISA_EXT_SVNAPOT:
-- 
2.44.1