Re: [PATCH v4 07/10] selftests: kvm: s390: Add uc_map_unmap VM test case

[Janosch Frank <frankja@linux.ibm.com>]

On 8/2/24 5:59 PM, Christoph Schlameuss wrote:
> Add a test case verifying basic running and interaction of ucontrol VMs.
> Fill the segment and page tables for allocated memory and map memory on
> first access.
> 
> * uc_map_unmap
>    Store and load data to mapped and unmapped memory and use pic segment
>    translation handling to map memory on access.
> 
> Signed-off-by: Christoph Schlameuss <schlameuss@linux.ibm.com>
> ---
>   .../selftests/kvm/s390x/ucontrol_test.c       | 165 +++++++++++++++++-
>   1 file changed, 164 insertions(+), 1 deletion(-)
> 
> diff --git a/tools/testing/selftests/kvm/s390x/ucontrol_test.c b/tools/testing/selftests/kvm/s390x/ucontrol_test.c
> index 030c59010fe1..72ad30fbe4ac 100644
> --- a/tools/testing/selftests/kvm/s390x/ucontrol_test.c
> +++ b/tools/testing/selftests/kvm/s390x/ucontrol_test.c
> @@ -16,7 +16,13 @@
>   #include <linux/capability.h>
>   #include <linux/sizes.h>

[...]

> +#define VM_MEM_MAX (VM_MEM_SIZE + VM_MEM_EXT_SIZE)

You defined this but never use it.
Instead you're still adding up VM_MEM_SIZE and VM_MEM_EXT_SIZE.

> +
> +#define PAGES_PER_SEGMENT 4

You mean pages per segment table?

[...]

> +/* initialize segment and page tables for uc_kvm tests */
> +static void init_st_pt(FIXTURE_DATA(uc_kvm) * self)
> +{
> +	struct kvm_sync_regs *sync_regs = &self->run->s.regs;
> +	struct kvm_run *run = self->run;
> +	void *se_addr;
> +	int si, pi;
> +	u64 *phd;
> +
> +	/* set PASCE addr */
> +	self->pgd = self->base_gpa + SZ_1M;
> +	phd = gpa2hva(self, self->pgd);
> +	memset(phd, 0xff, PAGES_PER_SEGMENT * PAGE_SIZE);
> +
> +	for (si = 0; si < ((VM_MEM_SIZE + VM_MEM_EXT_SIZE) / SZ_1M); si++) {
> +		/* create ste */
> +		phd[si] = (self->pgd
> +			+ (PAGES_PER_SEGMENT * PAGE_SIZE
> +				* ((VM_MEM_SIZE + VM_MEM_EXT_SIZE) / SZ_1M))
> +			+ (PAGES_PER_SEGMENT * PAGE_SIZE * si)) & ~0x7fful;
> +		se_addr = gpa2hva(self, phd[si]);
> +		memset(se_addr, 0xff, PAGES_PER_SEGMENT * PAGE_SIZE);
> +		for (pi = 0; pi < (SZ_1M / PAGE_SIZE); pi++) {
> +			/* create pte */
> +			((u64 *)se_addr)[pi] = (self->base_gpa
> +				+ (si * SZ_1M) + (pi * PAGE_SIZE)) & ~0xffful;
> +		}

That's barely readable, can you split that into functions or make it 
more readable in some other way?

> +	}
> +	pr_debug("segment table entry %p (0x%lx) --> %p\n",
> +		 phd, phd[0], gpa2hva(self, (phd[0] & ~0x7fful)));
> +	print_hex_bytes("st", (u64)phd, 64);
> +	print_hex_bytes("pt", (u64)gpa2hva(self, phd[0]), 128);
> +	print_hex_bytes("pt+", (u64)
> +			gpa2hva(self, phd[0] + (PAGES_PER_SEGMENT * PAGE_SIZE
> +			* ((VM_MEM_SIZE + VM_MEM_EXT_SIZE) / SZ_1M)) - 0x64), 128);
> +
> +	/* PASCE TT=00 for segment table */
> +	sync_regs->crs[1] = self->pgd | 0x3;
> +	run->kvm_dirty_regs |= KVM_SYNC_CRS;
> +}
> +