From d31b531cf8bcfe5f1fbdc4a636dbd4eb0210d03c Mon Sep 17 00:00:00 2001 From: Yong-Xuan Wang Date: Wed, 15 May 2024 17:11:28 +0800 Subject: [PATCH 1/3] target/riscv/kvm.c: Fix the hart bit setting of AIA In AIA spec, each hart (or each hart within a group) has a unique hart number to locate the memory pages of interrupt files in the address space. The number of bits required to represent any hart number is equal to ceil(log2(hmax + 1)), where hmax is the largest hart number among groups. However, if the largest hart number among groups is a power of 2, QEMU will pass an inaccurate hart-index-bit setting to Linux. For example, when the guest OS has 4 harts, only ceil(log2(3 + 1)) = 2 bits are sufficient to represent 4 harts, but we passes 3 to Linux. The code needs to be updated to ensure accurate hart-index-bit settings. Additionally, a Linux patch[1] is necessary to correctly recover the hart index when the guest OS has only 1 hart, where the hart-index-bit is 0. [1] https://lore.kernel.org/lkml/20240415064905.25184-1-yongxuan.wang@sifive.com/t/ Signed-off-by: Yong-Xuan Wang Reviewed-by: Andrew Jones Cc: qemu-stable Message-ID: <20240515091129.28116-1-yongxuan.wang@sifive.com> Signed-off-by: Alistair Francis --- target/riscv/kvm/kvm-cpu.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/target/riscv/kvm/kvm-cpu.c b/target/riscv/kvm/kvm-cpu.c index 117e33cf90..79e01db080 100644 --- a/target/riscv/kvm/kvm-cpu.c +++ b/target/riscv/kvm/kvm-cpu.c @@ -1432,7 +1432,14 @@ void kvm_riscv_aia_create(MachineState *machine, uint64_t group_shift, } } - hart_bits = find_last_bit(&max_hart_per_socket, BITS_PER_LONG) + 1; + + if (max_hart_per_socket > 1) { + max_hart_per_socket--; + hart_bits = find_last_bit(&max_hart_per_socket, BITS_PER_LONG) + 1; + } else { + hart_bits = 0; + } + ret = kvm_device_access(aia_fd, KVM_DEV_RISCV_AIA_GRP_CONFIG, KVM_DEV_RISCV_AIA_CONFIG_HART_BITS, &hart_bits, true, NULL); -- Gitee From 2cf4fcb323e69707c0d9f87a5d5024ed4a56abd3 Mon Sep 17 00:00:00 2001 From: Yong-Xuan Wang Date: Mon, 18 Dec 2023 09:05:41 +0000 Subject: [PATCH 2/3] target/riscv/kvm.c: remove group setting of KVM AIA if the machine only has 1 socket The emulated AIA within the Linux kernel restores the HART index of the IMSICs according to the configured AIA settings. During this process, the group setting is used only when the machine partitions harts into groups. It's unnecessary to set the group configuration if the machine has only one socket, as its address space might not contain the group shift. Signed-off-by: Yong-Xuan Wang Reviewed-by: Jim Shu Reviewed-by: Daniel Henrique Barboza Message-ID: <20231218090543.22353-2-yongxuan.wang@sifive.com> Signed-off-by: Alistair Francis --- target/riscv/kvm/kvm-cpu.c | 31 +++++++++++++++++-------------- 1 file changed, 17 insertions(+), 14 deletions(-) diff --git a/target/riscv/kvm/kvm-cpu.c b/target/riscv/kvm/kvm-cpu.c index 79e01db080..00bd4fa9c3 100644 --- a/target/riscv/kvm/kvm-cpu.c +++ b/target/riscv/kvm/kvm-cpu.c @@ -1376,21 +1376,24 @@ void kvm_riscv_aia_create(MachineState *machine, uint64_t group_shift, exit(1); } - socket_bits = find_last_bit(&socket_count, BITS_PER_LONG) + 1; - ret = kvm_device_access(aia_fd, KVM_DEV_RISCV_AIA_GRP_CONFIG, - KVM_DEV_RISCV_AIA_CONFIG_GROUP_BITS, - &socket_bits, true, NULL); - if (ret < 0) { - error_report("KVM AIA: failed to set group_bits"); - exit(1); - } - ret = kvm_device_access(aia_fd, KVM_DEV_RISCV_AIA_GRP_CONFIG, - KVM_DEV_RISCV_AIA_CONFIG_GROUP_SHIFT, - &group_shift, true, NULL); - if (ret < 0) { - error_report("KVM AIA: failed to set group_shift"); - exit(1); + if (socket_count > 1) { + socket_bits = find_last_bit(&socket_count, BITS_PER_LONG) + 1; + ret = kvm_device_access(aia_fd, KVM_DEV_RISCV_AIA_GRP_CONFIG, + KVM_DEV_RISCV_AIA_CONFIG_GROUP_BITS, + &socket_bits, true, NULL); + if (ret < 0) { + error_report("KVM AIA: failed to set group_bits"); + exit(1); + } + + ret = kvm_device_access(aia_fd, KVM_DEV_RISCV_AIA_GRP_CONFIG, + KVM_DEV_RISCV_AIA_CONFIG_GROUP_SHIFT, + &group_shift, true, NULL); + if (ret < 0) { + error_report("KVM AIA: failed to set group_shift"); + exit(1); + } } guest_bits = guest_num == 0 ? 0 : -- Gitee From 64752ff9e60ca83a391f6b4cb97d22347a4b7083 Mon Sep 17 00:00:00 2001 From: Andrew Jones Date: Wed, 21 Aug 2024 09:50:41 +0200 Subject: [PATCH 3/3] target/riscv/kvm: Fix the group bit setting of AIA Just as the hart bit setting of the AIA should be calculated as ceil(log2(max_hart_id + 1)) the group bit setting should be calculated as ceil(log2(max_group_id + 1)). The hart bits are implemented by passing max_hart_id to find_last_bit() and adding one to the result. Do the same for the group bit setting. Signed-off-by: Andrew Jones Reviewed-by: Daniel Henrique Barboza Message-ID: <20240821075040.498945-2-ajones@ventanamicro.com> Signed-off-by: Alistair Francis --- target/riscv/kvm/kvm-cpu.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/target/riscv/kvm/kvm-cpu.c b/target/riscv/kvm/kvm-cpu.c index 00bd4fa9c3..3d610beab6 100644 --- a/target/riscv/kvm/kvm-cpu.c +++ b/target/riscv/kvm/kvm-cpu.c @@ -1331,6 +1331,7 @@ void kvm_riscv_aia_create(MachineState *machine, uint64_t group_shift, uint64_t max_hart_per_socket = 0; uint64_t socket, base_hart, hart_count, socket_imsic_base, imsic_addr; uint64_t socket_bits, hart_bits, guest_bits; + uint64_t max_group_id; aia_fd = kvm_create_device(kvm_state, KVM_DEV_TYPE_RISCV_AIA, false); @@ -1378,7 +1379,8 @@ void kvm_riscv_aia_create(MachineState *machine, uint64_t group_shift, if (socket_count > 1) { - socket_bits = find_last_bit(&socket_count, BITS_PER_LONG) + 1; + max_group_id = socket_count - 1; + socket_bits = find_last_bit(&max_group_id, BITS_PER_LONG) + 1; ret = kvm_device_access(aia_fd, KVM_DEV_RISCV_AIA_GRP_CONFIG, KVM_DEV_RISCV_AIA_CONFIG_GROUP_BITS, &socket_bits, true, NULL); -- Gitee