Just realized that KVM/ARM now supports EL1 physical timer emulation
for guests and had a look at the patch set that enables VMs to use the EL1 physical timer through trap-and-emulate for arm64. I am using an
older KVM release which is causing guest termination on physical
timer access.


On 8/10/2017 3:01 AM, Kalra, Ashish wrote:

I have a general question on the ptimer test for KVM unit tests for the ARM/ARM64 platform, as the guest is only allowed to access to the physical counter and access to the physical timer is not allowed for the guest (CNTHCTL.EL1PCTEN is set and CNTHCTL.EL1PCEN is clear), so how is this ptimer test supposed to pass :

For example, in this test, reading CNTP_{CTL/CVAL}_EL0 will always cause exceptions while running in guest in the following function :

static void print_ptimer_info(void)
     printf("CNTPCT_EL0   : 0x%016lx\n", read_sysreg(cntpct_el0));
     printf("CNTP_CTL_EL0 : 0x%016lx\n", read_sysreg(cntp_ctl_el0));
     printf("CNTP_CVAL_EL0: 0x%016lx\n", read_sysreg(cntp_cval_el0));

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