[PATCH v1 11/11] KVM: s390: pv: add support for UV feature bits

Claudio Imbrenda
2021-05-17T20:08:20Z

Add support for Ultravisor feature bits, and take advantage of the
functionality advertised to speed up the lazy destroy mechanism.

Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
---
arch/s390/boot/uv.c | 1 +
arch/s390/include/asm/uv.h | 9 ++++++++-
arch/s390/kernel/uv.c | 3 ++-
3 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/arch/s390/boot/uv.c b/arch/s390/boot/uv.c
index 87641dd65ccf..efdb55364919 100644
--- a/arch/s390/boot/uv.c
+++ b/arch/s390/boot/uv.c
@@ -36,6 +36,7 @@ void uv_query_info(void)
uv_info.max_sec_stor_addr = ALIGN(uvcb.max_guest_stor_addr, PAGE_SIZE);
uv_info.max_num_sec_conf = uvcb.max_num_sec_conf;
uv_info.max_guest_cpu_id = uvcb.max_guest_cpu_id;
+ uv_info.feature_bits = uvcb.uv_feature_bits;
}

#ifdef CONFIG_PROTECTED_VIRTUALIZATION_GUEST
diff --git a/arch/s390/include/asm/uv.h b/arch/s390/include/asm/uv.h
index 1de5ff5e192a..808c2f0e0d7c 100644
--- a/arch/s390/include/asm/uv.h
+++ b/arch/s390/include/asm/uv.h
@@ -73,6 +73,11 @@ enum uv_cmds_inst {
BIT_UVC_CMD_UNPIN_PAGE_SHARED = 22,
};

+/* Bits in uv features field */
+enum uv_features {
+ BIT_UVC_FEAT_MISC_0 = 0,
+};
+
struct uv_cb_header {
u16 len;
u16 cmd; /* Command Code */
@@ -97,7 +102,8 @@ struct uv_cb_qui {
u64 max_guest_stor_addr;
u8 reserved88[158 - 136];
u16 max_guest_cpu_id;
- u8 reserveda0[200 - 160];
+ u64 uv_feature_bits;
+ u8 reserveda0[200 - 168];
} __packed __aligned(8);

/* Initialize Ultravisor */
@@ -274,6 +280,7 @@ struct uv_info {
unsigned long max_sec_stor_addr;
unsigned int max_num_sec_conf;
unsigned short max_guest_cpu_id;
+ unsigned long feature_bits;
};

extern struct uv_info uv_info;
diff --git a/arch/s390/kernel/uv.c b/arch/s390/kernel/uv.c
index 434d81baceed..b1fa38d5c388 100644
--- a/arch/s390/kernel/uv.c
+++ b/arch/s390/kernel/uv.c
@@ -291,7 +291,8 @@ static int make_secure_pte(pte_t *ptep, unsigned long addr,

static bool should_export_before_import(struct uv_cb_header *uvcb, struct mm_struct *mm)
{
- return uvcb->cmd != UVC_CMD_UNPIN_PAGE_SHARED &&
+ return !test_bit_inv(BIT_UVC_FEAT_MISC_0, &uv_info.feature_bits) &&
+ uvcb->cmd != UVC_CMD_UNPIN_PAGE_SHARED &&
atomic_read(&mm->context.is_protected) > 1;
}

--
2.31.1