| Message ID | 20241030160317.2528209-1-joey.gouly@arm.com (mailing list archive) |
|---|---|
| Headers | show |
| Series | KVM: arm64: Hide unsupported MPAM from the guest | expand |
Hi, Thanks for respinning this Joey. On Wed, Oct 30, 2024 at 04:03:10PM +0000, Joey Gouly wrote: > Hi, > > changes since v5 [1]: > - Removed Kconfig option, the KVM traps shouldn't rely on host kernel support > - Renamed cpus_support_* to system_supports_* since that matches other functions > - Replace static branch arm64_mpam_has_hcr with a normal cpufeature capability > - Add MPAM*_EL2 regs to KVM (undef_access) > - Use constants in the test, instead of hardcoded values > - Added R-b and T-b tags > - Rebased on v6.12-rc5 > > James wrote: > This series fixes up a long standing bug where MPAM was accidentally exposed > to a guest, but the feature was not otherwise trapped or context switched. > This could result in KVM warning about unexpected traps, and injecting an > undef into the guest contradicting the ID registers. > This would prevent an MPAM aware kernel from booting - fortunately, there > aren't any of those. > > Ideally, we'd take the MPAM feature away from the ID registers, but that > would leave existing guests unable to migrate to a newer kernel. Instead, > just ignore that field when it matches the hardware. KVM wasn't going to > expose MPAM anyway. The guest will not see MPAM in the id registers. > > This series includes the head.S and KVM changes to enable/disable traps. If > MPAM is neither enabled nor emulated by EL3 firmware, these system register > accesses will trap to EL3. > If your kernel doesn't boot, and the problem bisects here - please update > your firmware. MPAM has been supported by trusted firmware since v1.6 in > 2018. (also noted on patch 3). This is looking pretty good to me, and I'd really like to have it in for 6.13. Will/Catalin, first 3 patches look OK to you?
On Wed, 30 Oct 2024 16:03:10 +0000, Joey Gouly <joey.gouly@arm.com> wrote: > > Hi, > > changes since v5 [1]: > - Removed Kconfig option, the KVM traps shouldn't rely on host kernel support > - Renamed cpus_support_* to system_supports_* since that matches other functions > - Replace static branch arm64_mpam_has_hcr with a normal cpufeature capability > - Add MPAM*_EL2 regs to KVM (undef_access) > - Use constants in the test, instead of hardcoded values > - Added R-b and T-b tags > - Rebased on v6.12-rc5 > > James wrote: > This series fixes up a long standing bug where MPAM was accidentally exposed > to a guest, but the feature was not otherwise trapped or context switched. > This could result in KVM warning about unexpected traps, and injecting an > undef into the guest contradicting the ID registers. > This would prevent an MPAM aware kernel from booting - fortunately, there > aren't any of those. > > Ideally, we'd take the MPAM feature away from the ID registers, but that > would leave existing guests unable to migrate to a newer kernel. Instead, > just ignore that field when it matches the hardware. KVM wasn't going to > expose MPAM anyway. The guest will not see MPAM in the id registers. > > This series includes the head.S and KVM changes to enable/disable traps. If > MPAM is neither enabled nor emulated by EL3 firmware, these system register > accesses will trap to EL3. > If your kernel doesn't boot, and the problem bisects here - please update > your firmware. MPAM has been supported by trusted firmware since v1.6 in > 2018. (also noted on patch 3). > > Thanks, > Joey > > [1] https://lore.kernel.org/kvmarm/20241015133923.3910916-1-joey.gouly@arm.com/ > > James Morse (7): > arm64/sysreg: Convert existing MPAM sysregs and add the remaining > entries > arm64: head.S: Initialise MPAM EL2 registers and disable traps > arm64: cpufeature: discover CPU support for MPAM > KVM: arm64: Fix missing traps of guest accesses to the MPAM registers > KVM: arm64: Add a macro for creating filtered sys_reg_descs entries > KVM: arm64: Disable MPAM visibility by default and ignore VMM writes > KVM: arm64: selftests: Test ID_AA64PFR0.MPAM isn't completely ignored > > .../arch/arm64/cpu-feature-registers.rst | 2 + > arch/arm64/include/asm/cpu.h | 1 + > arch/arm64/include/asm/cpucaps.h | 5 + > arch/arm64/include/asm/cpufeature.h | 17 ++ > arch/arm64/include/asm/el2_setup.h | 14 ++ > arch/arm64/include/asm/kvm_arm.h | 1 + > arch/arm64/include/asm/sysreg.h | 12 -- > arch/arm64/kernel/cpufeature.c | 96 +++++++++++ > arch/arm64/kernel/cpuinfo.c | 3 + > arch/arm64/kvm/hyp/include/hyp/switch.h | 31 ++++ > arch/arm64/kvm/sys_regs.c | 121 +++++++++---- > arch/arm64/tools/cpucaps | 2 + > arch/arm64/tools/sysreg | 161 ++++++++++++++++++ > .../selftests/kvm/aarch64/set_id_regs.c | 99 ++++++++++- > 14 files changed, 523 insertions(+), 42 deletions(-) For the series: Reviewed-by: Marc Zyngier <maz@kernel.org> M.
On Wed, 30 Oct 2024 16:03:10 +0000, Joey Gouly wrote: > changes since v5 [1]: > - Removed Kconfig option, the KVM traps shouldn't rely on host kernel support > - Renamed cpus_support_* to system_supports_* since that matches other functions > - Replace static branch arm64_mpam_has_hcr with a normal cpufeature capability > - Add MPAM*_EL2 regs to KVM (undef_access) > - Use constants in the test, instead of hardcoded values > - Added R-b and T-b tags > - Rebased on v6.12-rc5 > > [...] Applied to kvmarm/next, thanks! [1/7] arm64/sysreg: Convert existing MPAM sysregs and add the remaining entries https://git.kernel.org/kvmarm/kvmarm/c/83732ce6a056 [2/7] arm64: head.S: Initialise MPAM EL2 registers and disable traps https://git.kernel.org/kvmarm/kvmarm/c/23b33d1e168c [3/7] arm64: cpufeature: discover CPU support for MPAM https://git.kernel.org/kvmarm/kvmarm/c/09e6b306f3ba [4/7] KVM: arm64: Fix missing traps of guest accesses to the MPAM registers https://git.kernel.org/kvmarm/kvmarm/c/31ff96c38ea3 [5/7] KVM: arm64: Add a macro for creating filtered sys_reg_descs entries https://git.kernel.org/kvmarm/kvmarm/c/7da540e29dea [6/7] KVM: arm64: Disable MPAM visibility by default and ignore VMM writes https://git.kernel.org/kvmarm/kvmarm/c/6685f5d572c2 [7/7] KVM: arm64: selftests: Test ID_AA64PFR0.MPAM isn't completely ignored https://git.kernel.org/kvmarm/kvmarm/c/75cd027cbcb1 -- Best, Oliver
Hi, changes since v5 [1]: - Removed Kconfig option, the KVM traps shouldn't rely on host kernel support - Renamed cpus_support_* to system_supports_* since that matches other functions - Replace static branch arm64_mpam_has_hcr with a normal cpufeature capability - Add MPAM*_EL2 regs to KVM (undef_access) - Use constants in the test, instead of hardcoded values - Added R-b and T-b tags - Rebased on v6.12-rc5 James wrote: This series fixes up a long standing bug where MPAM was accidentally exposed to a guest, but the feature was not otherwise trapped or context switched. This could result in KVM warning about unexpected traps, and injecting an undef into the guest contradicting the ID registers. This would prevent an MPAM aware kernel from booting - fortunately, there aren't any of those. Ideally, we'd take the MPAM feature away from the ID registers, but that would leave existing guests unable to migrate to a newer kernel. Instead, just ignore that field when it matches the hardware. KVM wasn't going to expose MPAM anyway. The guest will not see MPAM in the id registers. This series includes the head.S and KVM changes to enable/disable traps. If MPAM is neither enabled nor emulated by EL3 firmware, these system register accesses will trap to EL3. If your kernel doesn't boot, and the problem bisects here - please update your firmware. MPAM has been supported by trusted firmware since v1.6 in 2018. (also noted on patch 3). Thanks, Joey [1] https://lore.kernel.org/kvmarm/20241015133923.3910916-1-joey.gouly@arm.com/ James Morse (7): arm64/sysreg: Convert existing MPAM sysregs and add the remaining entries arm64: head.S: Initialise MPAM EL2 registers and disable traps arm64: cpufeature: discover CPU support for MPAM KVM: arm64: Fix missing traps of guest accesses to the MPAM registers KVM: arm64: Add a macro for creating filtered sys_reg_descs entries KVM: arm64: Disable MPAM visibility by default and ignore VMM writes KVM: arm64: selftests: Test ID_AA64PFR0.MPAM isn't completely ignored .../arch/arm64/cpu-feature-registers.rst | 2 + arch/arm64/include/asm/cpu.h | 1 + arch/arm64/include/asm/cpucaps.h | 5 + arch/arm64/include/asm/cpufeature.h | 17 ++ arch/arm64/include/asm/el2_setup.h | 14 ++ arch/arm64/include/asm/kvm_arm.h | 1 + arch/arm64/include/asm/sysreg.h | 12 -- arch/arm64/kernel/cpufeature.c | 96 +++++++++++ arch/arm64/kernel/cpuinfo.c | 3 + arch/arm64/kvm/hyp/include/hyp/switch.h | 31 ++++ arch/arm64/kvm/sys_regs.c | 121 +++++++++---- arch/arm64/tools/cpucaps | 2 + arch/arm64/tools/sysreg | 161 ++++++++++++++++++ .../selftests/kvm/aarch64/set_id_regs.c | 99 ++++++++++- 14 files changed, 523 insertions(+), 42 deletions(-)