linux-kernel - Re: [PATCH kvm-unit-tests v2 1/3] svm: Add ability to execute test via test

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Date:   Thu, 5 Nov 2020 18:20:26 +0100
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Cathy Avery <cavery@...hat.com>, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org
Subject: Re: [PATCH kvm-unit-tests v2 1/3] svm: Add ability to execute test
 via test_run on a vcpu other than vcpu 0

On 17/07/20 13:34, Cathy Avery wrote:
> When running tests that can result in a vcpu being left in an
> indeterminate state it is useful to be able to run the test on
> a vcpu other than 0. This patch allows test_run to be executed
> on any vcpu indicated by the on_vcpu member of the svm_test struct.
> The initialized state of the vcpu0 registers used to populate the
> vmcb is carried forward to the other vcpus.
> 
> Signed-off-by: Cathy Avery <cavery@...hat.com>
> ---
>   lib/x86/vm.c | 18 ++++++++++++++++++
>   lib/x86/vm.h |  7 +++++++
>   x86/svm.c    | 24 +++++++++++++++++++++++-
>   x86/svm.h    |  2 ++
>   4 files changed, 50 insertions(+), 1 deletion(-)
> 
> diff --git a/lib/x86/vm.c b/lib/x86/vm.c
> index 41d6d96..e223bb4 100644
> --- a/lib/x86/vm.c
> +++ b/lib/x86/vm.c
> @@ -2,6 +2,7 @@
>   #include "libcflat.h"
>   #include "vmalloc.h"
>   #include "alloc_page.h"
> +#include "smp.h"
>   
>   pteval_t *install_pte(pgd_t *cr3,
>   		      int pte_level,
> @@ -139,9 +140,18 @@ static void setup_mmu_range(pgd_t *cr3, phys_addr_t start, size_t len)
>   	install_pages(cr3, phys, max - phys, (void *)(ulong)phys);
>   }
>   
> +static void set_additional_vcpu_vmregs(struct vm_vcpu_info *info)
> +{
> +	write_cr3(info->cr3);
> +	write_cr4(info->cr4);
> +	write_cr0(info->cr0);
> +}
> +
>   void *setup_mmu(phys_addr_t end_of_memory)
>   {
>       pgd_t *cr3 = alloc_page();
> +    struct vm_vcpu_info info;
> +    int i;
>   
>       memset(cr3, 0, PAGE_SIZE);
>   
> @@ -166,6 +176,14 @@ void *setup_mmu(phys_addr_t end_of_memory)
>       printf("cr0 = %lx\n", read_cr0());
>       printf("cr3 = %lx\n", read_cr3());
>       printf("cr4 = %lx\n", read_cr4());
> +
> +    info.cr3 = read_cr3();
> +    info.cr4 = read_cr4();
> +    info.cr0 = read_cr0();
> +
> +    for (i = 1; i < cpu_count(); i++)
> +        on_cpu(i, (void *)set_additional_vcpu_vmregs, &info);
> +
>       return cr3;
>   }
>   
> diff --git a/lib/x86/vm.h b/lib/x86/vm.h
> index 8750a1e..3a1432f 100644
> --- a/lib/x86/vm.h
> +++ b/lib/x86/vm.h
> @@ -45,4 +45,11 @@ static inline void *current_page_table(void)
>   
>   void split_large_page(unsigned long *ptep, int level);
>   void force_4k_page(void *addr);
> +
> +struct vm_vcpu_info {
> +        u64 cr3;
> +        u64 cr4;
> +        u64 cr0;
> +};
> +
>   #endif
> diff --git a/x86/svm.c b/x86/svm.c
> index d8c8272..975c477 100644
> --- a/x86/svm.c
> +++ b/x86/svm.c
> @@ -275,6 +275,17 @@ static void test_run(struct svm_test *test)
>   	irq_enable();
>   
>   	report(test->succeeded(test), "%s", test->name);
> +
> +        if (test->on_vcpu)
> +	    test->on_vcpu_done = true;
> +}
> +
> +static void set_additional_vpcu_msr(void *msr_efer)
> +{
> +	void *hsave = alloc_page();
> +
> +	wrmsr(MSR_VM_HSAVE_PA, virt_to_phys(hsave));
> +	wrmsr(MSR_EFER, (ulong)msr_efer | EFER_SVME | EFER_NX);
>   }
>   
>   static void setup_svm(void)
> @@ -294,6 +305,9 @@ static void setup_svm(void)
>   	if (!npt_supported())
>   		return;
>   
> +	for (i = 1; i < cpu_count(); i++)
> +		on_cpu(i, (void *)set_additional_vpcu_msr, (void *)rdmsr(MSR_EFER));
> +
>   	printf("NPT detected - running all tests with NPT enabled\n");
>   
>   	/*
> @@ -396,7 +410,15 @@ int main(int ac, char **av)
>   		if (svm_tests[i].supported && !svm_tests[i].supported())
>   			continue;
>   		if (svm_tests[i].v2 == NULL) {
> -			test_run(&svm_tests[i]);
> +			if (svm_tests[i].on_vcpu) {
> +				if (cpu_count() <= svm_tests[i].on_vcpu)
> +					continue;
> +				on_cpu_async(svm_tests[i].on_vcpu, (void *)test_run, &svm_tests[i]);
> +				while (!svm_tests[i].on_vcpu_done)
> +					cpu_relax();
> +			}
> +			else
> +				test_run(&svm_tests[i]);
>   		} else {
>   			vmcb_ident(vmcb);
>   			v2_test = &(svm_tests[i]);
> diff --git a/x86/svm.h b/x86/svm.h
> index f8e7429..1e60d52 100644
> --- a/x86/svm.h
> +++ b/x86/svm.h
> @@ -348,6 +348,8 @@ struct svm_test {
>   	ulong scratch;
>   	/* Alternative test interface. */
>   	void (*v2)(void);
> +	int on_vcpu;
> +	bool on_vcpu_done;
>   };
>   
>   struct regs {
> 

Queued, thanks.

Paolo