This is a note to let you know that I've just added the patch titled
KVM: arm64: Advertise ID_AA64PFR0_EL1.CSV2/3 to protected VMs
to the 6.1-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
kvm-arm64-advertise-id_aa64pfr0_el1.csv2-3-to-protec.patch
and it can be found in the queue-6.1 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit b6d0bfc4107bb203b1fd142c363a4258006c792b
Author: Fuad Tabba <tabba@xxxxxxxxxx>
Date: Tue Apr 4 16:23:21 2023 +0100
KVM: arm64: Advertise ID_AA64PFR0_EL1.CSV2/3 to protected VMs
[ Upstream commit e81625218bf7986ba1351a98c43d346b15601d26 ]
The existing pKVM code attempts to advertise CSV2/3 using values
initialized to 0, but never set. To advertise CSV2/3 to protected
guests, pass the CSV2/3 values to hyp when initializing hyp's
view of guests' ID_AA64PFR0_EL1.
Similar to non-protected KVM, these are system-wide, rather than
per cpu, for simplicity.
Fixes: 6c30bfb18d0b ("KVM: arm64: Add handlers for protected VM System Registers")
Signed-off-by: Fuad Tabba <tabba@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20230404152321.413064-1-tabba@xxxxxxxxxx
Signed-off-by: Oliver Upton <oliver.upton@xxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index e40606a560997..6ce6888cf73d6 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -1870,9 +1870,33 @@ static int do_pkvm_init(u32 hyp_va_bits)
return ret;
}
+static u64 get_hyp_id_aa64pfr0_el1(void)
+{
+ /*
+ * Track whether the system isn't affected by spectre/meltdown in the
+ * hypervisor's view of id_aa64pfr0_el1, used for protected VMs.
+ * Although this is per-CPU, we make it global for simplicity, e.g., not
+ * to have to worry about vcpu migration.
+ *
+ * Unlike for non-protected VMs, userspace cannot override this for
+ * protected VMs.
+ */
+ u64 val = read_sanitised_ftr_reg(SYS_ID_AA64PFR0_EL1);
+
+ val &= ~(ARM64_FEATURE_MASK(ID_AA64PFR0_EL1_CSV2) |
+ ARM64_FEATURE_MASK(ID_AA64PFR0_EL1_CSV3));
+
+ val |= FIELD_PREP(ARM64_FEATURE_MASK(ID_AA64PFR0_EL1_CSV2),
+ arm64_get_spectre_v2_state() == SPECTRE_UNAFFECTED);
+ val |= FIELD_PREP(ARM64_FEATURE_MASK(ID_AA64PFR0_EL1_CSV3),
+ arm64_get_meltdown_state() == SPECTRE_UNAFFECTED);
+
+ return val;
+}
+
static void kvm_hyp_init_symbols(void)
{
- kvm_nvhe_sym(id_aa64pfr0_el1_sys_val) = read_sanitised_ftr_reg(SYS_ID_AA64PFR0_EL1);
+ kvm_nvhe_sym(id_aa64pfr0_el1_sys_val) = get_hyp_id_aa64pfr0_el1();
kvm_nvhe_sym(id_aa64pfr1_el1_sys_val) = read_sanitised_ftr_reg(SYS_ID_AA64PFR1_EL1);
kvm_nvhe_sym(id_aa64isar0_el1_sys_val) = read_sanitised_ftr_reg(SYS_ID_AA64ISAR0_EL1);
kvm_nvhe_sym(id_aa64isar1_el1_sys_val) = read_sanitised_ftr_reg(SYS_ID_AA64ISAR1_EL1);
diff --git a/arch/arm64/kvm/hyp/include/nvhe/fixed_config.h b/arch/arm64/kvm/hyp/include/nvhe/fixed_config.h
index 07edfc7524c94..37440e1dda930 100644
--- a/arch/arm64/kvm/hyp/include/nvhe/fixed_config.h
+++ b/arch/arm64/kvm/hyp/include/nvhe/fixed_config.h
@@ -33,11 +33,14 @@
* Allow for protected VMs:
* - Floating-point and Advanced SIMD
* - Data Independent Timing
+ * - Spectre/Meltdown Mitigation
*/
#define PVM_ID_AA64PFR0_ALLOW (\
ARM64_FEATURE_MASK(ID_AA64PFR0_EL1_FP) | \
ARM64_FEATURE_MASK(ID_AA64PFR0_EL1_AdvSIMD) | \
- ARM64_FEATURE_MASK(ID_AA64PFR0_EL1_DIT) \
+ ARM64_FEATURE_MASK(ID_AA64PFR0_EL1_DIT) | \
+ ARM64_FEATURE_MASK(ID_AA64PFR0_EL1_CSV2) | \
+ ARM64_FEATURE_MASK(ID_AA64PFR0_EL1_CSV3) \
)
/*
diff --git a/arch/arm64/kvm/hyp/nvhe/sys_regs.c b/arch/arm64/kvm/hyp/nvhe/sys_regs.c
index 0f9ac25afdf40..3d5121ee39777 100644
--- a/arch/arm64/kvm/hyp/nvhe/sys_regs.c
+++ b/arch/arm64/kvm/hyp/nvhe/sys_regs.c
@@ -84,19 +84,12 @@ static u64 get_restricted_features_unsigned(u64 sys_reg_val,
static u64 get_pvm_id_aa64pfr0(const struct kvm_vcpu *vcpu)
{
- const struct kvm *kvm = (const struct kvm *)kern_hyp_va(vcpu->kvm);
u64 set_mask = 0;
u64 allow_mask = PVM_ID_AA64PFR0_ALLOW;
set_mask |= get_restricted_features_unsigned(id_aa64pfr0_el1_sys_val,
PVM_ID_AA64PFR0_RESTRICT_UNSIGNED);
- /* Spectre and Meltdown mitigation in KVM */
- set_mask |= FIELD_PREP(ARM64_FEATURE_MASK(ID_AA64PFR0_EL1_CSV2),
- (u64)kvm->arch.pfr0_csv2);
- set_mask |= FIELD_PREP(ARM64_FEATURE_MASK(ID_AA64PFR0_EL1_CSV3),
- (u64)kvm->arch.pfr0_csv3);
-
return (id_aa64pfr0_el1_sys_val & allow_mask) | set_mask;
}
