| Message ID | 20250210195226.1215254-1-mark.rutland@arm.com (mailing list archive) |
|---|---|
| Headers | show |
| Series | KVM: arm64: FPSIMD/SVE/SME fixes | expand |
On Mon, Feb 10, 2025 at 07:52:18PM +0000, Mark Rutland wrote: > These patches fix some issues with the way KVM manages FPSIMD/SVE/SME > state. The series supersedes my earlier attempt at fixing the host SVE > state corruption issue: > > https://lore.kernel.org/linux-arm-kernel/20250121100026.3974971-1-mark.rutland@arm.com/ > > Patch 1 addresses the host SVE state corruption issue by always saving > and unbinding the host state when loading a vCPU, as discussed on the > earlier patch: > > https://lore.kernel.org/linux-arm-kernel/Z4--YuG5SWrP_pW7@J2N7QTR9R3/ > https://lore.kernel.org/linux-arm-kernel/86plkful48.wl-maz@kernel.org/ > > Patches 2 to 4 remove code made redundant by patch 1. These probably > warrant backporting along with patch 1 as there is some historical > brokenness in the code they remove. > > Patches 5 to 7 are preparatory refactoring for patch 8, and are not > intended to have any functional impact. > > Patch 8 addresses some mismanagement of ZCR_EL{1,2} which can result in > the host VMM unexpectedly receiving a SIGKILL. To fix this, we eagerly > switch ZCR_EL{1,2} at guest<->host transitions, as discussed on another > series: > > https://lore.kernel.org/linux-arm-kernel/Z4pAMaEYvdLpmbg2@J2N7QTR9R3/ > https://lore.kernel.org/linux-arm-kernel/86o6zzukwr.wl-maz@kernel.org/ > https://lore.kernel.org/linux-arm-kernel/Z5Dc-WMu2azhTuMn@J2N7QTR9R3/ > > The end result is that KVM loses ~100 lines of code, and becomes a bit > simpler to reason about. LGTM, although a minor nitpick would be to repack the host data flags at the end of purging SVE/SME. Reviewed-by: Oliver Upton <oliver.upton@linux.dev>
On Mon, 10 Feb 2025 19:52:18 +0000, Mark Rutland wrote: > These patches fix some issues with the way KVM manages FPSIMD/SVE/SME > state. The series supersedes my earlier attempt at fixing the host SVE > state corruption issue: > > https://lore.kernel.org/linux-arm-kernel/20250121100026.3974971-1-mark.rutland@arm.com/ > > Patch 1 addresses the host SVE state corruption issue by always saving > and unbinding the host state when loading a vCPU, as discussed on the > earlier patch: > > [...] Applied to fixes, thanks! [1/8] KVM: arm64: Unconditionally save+flush host FPSIMD/SVE/SME state commit: b671313b36591cab3d4cb4fe40ffdbac213635d1 [2/8] KVM: arm64: Remove host FPSIMD saving for non-protected KVM commit: f000c2b1bcb471e35bb65cc0f0c31cb18d8677d8 [3/8] KVM: arm64: Remove VHE host restore of CPACR_EL1.ZEN commit: 82695cf636f155917eae61b9f86565184a683d76 [4/8] KVM: arm64: Remove VHE host restore of CPACR_EL1.SMEN commit: 8adb7db3c85f917ca59a76205e4be1ee82a289da [5/8] KVM: arm64: Refactor CPTR trap deactivation commit: 1afdd3f832570aa27ae82819020bd319820337ce [6/8] KVM: arm64: Refactor exit handlers commit: d59128af7ac954f80636548a60f1b1b41a7d067f [7/8] KVM: arm64: Mark some header functions as inline commit: 03ce3e0db4f42252de4eeae01c5e5fa832af7585 [8/8] KVM: arm64: Eagerly switch ZCR_EL{1,2} commit: 9a053b84b508b32b824d4a088cf3f5091a3e7c15 Cheers, M.
These patches fix some issues with the way KVM manages FPSIMD/SVE/SME state. The series supersedes my earlier attempt at fixing the host SVE state corruption issue: https://lore.kernel.org/linux-arm-kernel/20250121100026.3974971-1-mark.rutland@arm.com/ Patch 1 addresses the host SVE state corruption issue by always saving and unbinding the host state when loading a vCPU, as discussed on the earlier patch: https://lore.kernel.org/linux-arm-kernel/Z4--YuG5SWrP_pW7@J2N7QTR9R3/ https://lore.kernel.org/linux-arm-kernel/86plkful48.wl-maz@kernel.org/ Patches 2 to 4 remove code made redundant by patch 1. These probably warrant backporting along with patch 1 as there is some historical brokenness in the code they remove. Patches 5 to 7 are preparatory refactoring for patch 8, and are not intended to have any functional impact. Patch 8 addresses some mismanagement of ZCR_EL{1,2} which can result in the host VMM unexpectedly receiving a SIGKILL. To fix this, we eagerly switch ZCR_EL{1,2} at guest<->host transitions, as discussed on another series: https://lore.kernel.org/linux-arm-kernel/Z4pAMaEYvdLpmbg2@J2N7QTR9R3/ https://lore.kernel.org/linux-arm-kernel/86o6zzukwr.wl-maz@kernel.org/ https://lore.kernel.org/linux-arm-kernel/Z5Dc-WMu2azhTuMn@J2N7QTR9R3/ The end result is that KVM loses ~100 lines of code, and becomes a bit simpler to reason about. I've pushed these patches to the arm64-kvm-fpsimd-fixes-20250210 tag on my kernel.org repo: https://git.kernel.org/pub/scm/linux/kernel/git/mark/linux.git/ git://git.kernel.org/pub/scm/linux/kernel/git/mark/linux.git The (unstable) arm64/kvm/fpsimd-fixes branch in that repo contains the fixes plus additional debug patches I've used for testing. I've given this some basic testing on a virtual platform, booting a host and a guest with and without constraining the guest's max SVE VL, with: * kvm_arm.mode=vhe * kvm_arm.mode=nvhe * kvm_arm.mode=protected (IIUC this will default to hVHE) Since v1 [1]: * Address some additional compiler warnings in patch 7 * Use ZCR_EL1 alias in VHE code * Fold in Tested-by and Reviewed-by tags * Fix typos Since v2 [2]: * Ensure context synchronization in patch 8 * Fold in Tested-by and Reviewed-by tags * Fix typos [1] https://lore.kernel.org/linux-arm-kernel/20250204152100.705610-1-mark.rutland@arm.com/ [2] https://lore.kernel.org/linux-arm-kernel/20250206141102.954688-1-mark.rutland@arm.com/ Mark. Mark Rutland (8): KVM: arm64: Unconditionally save+flush host FPSIMD/SVE/SME state KVM: arm64: Remove host FPSIMD saving for non-protected KVM KVM: arm64: Remove VHE host restore of CPACR_EL1.ZEN KVM: arm64: Remove VHE host restore of CPACR_EL1.SMEN KVM: arm64: Refactor CPTR trap deactivation KVM: arm64: Refactor exit handlers KVM: arm64: Mark some header functions as inline KVM: arm64: Eagerly switch ZCR_EL{1,2} arch/arm64/include/asm/kvm_emulate.h | 42 -------- arch/arm64/include/asm/kvm_host.h | 22 +--- arch/arm64/kernel/fpsimd.c | 25 ----- arch/arm64/kvm/arm.c | 8 -- arch/arm64/kvm/fpsimd.c | 100 ++---------------- arch/arm64/kvm/hyp/entry.S | 5 + arch/arm64/kvm/hyp/include/hyp/switch.h | 133 +++++++++++++++++------- arch/arm64/kvm/hyp/nvhe/hyp-main.c | 15 ++- arch/arm64/kvm/hyp/nvhe/switch.c | 91 ++++++++-------- arch/arm64/kvm/hyp/vhe/switch.c | 33 +++--- 10 files changed, 187 insertions(+), 287 deletions(-)